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The Analysis of Mind

by Bertrand Russell

February, 2001 [Etext #2529]

The Project Gutenberg Etext of The Analysis of Mind by Bertrand Russell

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An admirable statement of the aims of the Library of Philosophy

was provided by the first editor, the late Professor J. H.

Muirhead, in his description of the original programme printed in

Erdmann's History of Philosophy under the date 1890. This was

slightly modified in subsequent volumes to take the form of the

following statement:

"The Muirhead Library of Philosophy was designed as a

contribution to the History of Modern Philosophy under the heads:

first of Different Schools of Thought--Sensationalist, Realist,

Idealist, Intuitivist; secondly of different

Subjects--Psychology, Ethics, Aesthetics, Political Philosophy,

Theology. While much had been done in England in tracing the

course of evolution in nature, history, economics, morals and

religion, little had been done in tracing the development of

thought on these subjects. Yet 'the evolution of opinion is part

of the whole evolution'.

"By the co-operation of different writers in carrying out this

plan it was hoped that a thoroughness and completeness of

treatment, otherwise unattainable, might be secured. It was

believed also that from writers mainly British and American

fuller consideration of English Philosophy than it had hitherto

received might be looked for. In the earlier series of books

containing, among others, Bosanquet's "History of Aesthetic,"

Pfleiderer's "Rational Theology since Kant," Albee's "History of

English Utilitarianism," Bonar's "Philosophy and Political

Economy," Brett's "History of Psychology," Ritchie's "Natural

Rights," these objects were to a large extent effected.

"In the meantime original work of a high order was being produced

both in England and America by such writers as Bradley, Stout,

Bertrand Russell, Baldwin, Urban, Montague, and others, and a new

interest in foreign works, German, French and Italian, which had

either become classical or were attracting public attention, had

developed. The scope of the Library thus became extended into

something more international, and it is entering on the fifth

decade of its existence in the hope that it may contribute to

that mutual understanding between countries which is so pressing

a need of the present time."

The need which Professor Muirhead stressed is no less pressing

to-day, and few will deny that philosophy has much to do with

enabling us to meet it, although no one, least of all Muirhead

himself, would regard that as the sole, or even the main, object

of philosophy. As Professor Muirhead continues to lend the

distinction of his name to the Library of Philosophy it seemed

not inappropriate to allow him to recall us to these aims in his

own words. The emphasis on the history of thought also seemed to

me very timely; and the number of important works promised for

the Library in the very near future augur well for the continued

fulfilment, in this and other ways, of the expectations of the

original editor.

H. D. Lewis


This book has grown out of an attempt to harmonize two different

tendencies, one in psychology, the other in physics, with both of

which I find myself in sympathy, although at first sight they

might seem inconsistent. On the one hand, many psychologists,

especially those of the behaviourist school, tend to adopt what

is essentially a materialistic position, as a matter of method if

not of metaphysics. They make psychology increasingly dependent

on physiology and external observation, and tend to think of

matter as something much more solid and indubitable than mind.

Meanwhile the physicists, especially Einstein and other exponents

of the theory of relativity, have been making "matter" less and

less material. Their world consists of "events," from which

"matter" is derived by a logical construction. Whoever reads, for

example, Professor Eddington's "Space, Time and Gravitation"

(Cambridge University Press, 1920), will see that an

old-fashioned materialism can receive no support from modern

physics. I think that what has permanent value in the outlook of

the behaviourists is the feeling that physics is the most

fundamental science at present in existence. But this position

cannot be called materialistic, if, as seems to be the case,

physics does not assume the existence of matter.

The view that seems to me to reconcile the materialistic tendency

of psychology with the anti-materialistic tendency of physics is

the view of William James and the American new realists,

according to which the "stuff" of the world is neither mental nor

material, but a "neutral stuff," out of which both are

constructed. I have endeavoured in this work to develop this view

in some detail as regards the phenomena with which psychology is


My thanks are due to Professor John B. Watson and to Dr. T. P.

Nunn for reading my MSS. at an early stage and helping me with

many valuable suggestions; also to Mr. A. Wohlgemuth for much

very useful information as regards important literature. I have

also to acknowledge the help of the editor of this Library of

Philosophy, Professor Muirhead, for several suggestions by which

I have profited.

The work has been given in the form of lectures both in London

and Peking, and one lecture, that on Desire, has been published

in the Athenaeum.

There are a few allusions to China in this book, all of which

were written before I had been in China, and are not intended to

be taken by the reader as geographically accurate. I have used

"China" merely as a synonym for "a distant country," when I

wanted illustrations of unfamiliar things.

Peking, January 1921.


I. Recent Criticisms of "Consciousness" II. Instinct and Habit

III. Desire and Feeling IV. Influence of Past History on Present

Occurrences in Living Organisms V. Psychological and

Physical Causal Laws VI. Introspection VII. The Definition of

Perception VIII.Sensations and Images IX. Memory X. Words and

Meaning XI. General Ideas and Thought XII. Belief XIII.Truth and

Falsehood XIV. Emotions and Will XV. Characteristics of Mental




There are certain occurrences which we are in the habit of

calling "mental." Among these we may take as typical BELIEVING

and DESIRING. The exact definition of the word "mental" will, I

hope, emerge as the lectures proceed; for the present, I shall

mean by it whatever occurrences would commonly be called mental.

I wish in these lectures to analyse as fully as I can what it is

that really takes place when we, e.g. believe or desire. In this

first lecture I shall be concerned to refute a theory which is

widely held, and which I formerly held myself: the theory that

the essence of everything mental is a certain quite peculiar

something called "consciousness," conceived either as a relation

to objects, or as a pervading quality of psychical phenomena.

The reasons which I shall give against this theory will be mainly

derived from previous authors. There are two sorts of reasons,

which will divide my lecture into two parts

(1) Direct reasons, derived from analysis and its difficulties;

(2) Indirect reasons, derived from observation of animals

(comparative psychology) and of the insane and hysterical


Few things are more firmly established in popular philosophy than

the distinction between mind and matter. Those who are not

professional metaphysicians are willing to confess that they do

not know what mind actually is, or how matter is constituted; but

they remain convinced that there is an impassable gulf between

the two, and that both belong to what actually exists in the

world. Philosophers, on the other hand, have maintained often

that matter is a mere fiction imagined by mind, and sometimes

that mind is a mere property of a certain kind of matter. Those

who maintain that mind is the reality and matter an evil dream

are called "idealists"--a word which has a different meaning in

philosophy from that which it bears in ordinary life. Those who

argue that matter is the reality and mind a mere property of

protoplasm are called "materialists." They have been rare among

philosophers, but common, at certain periods, among men of

science. Idealists, materialists, and ordinary mortals have been

in agreement on one point: that they knew sufficiently what they

meant by the words "mind" and "matter" to be able to conduct

their debate intelligently. Yet it was just in this point, as to

which they were at one, that they seem to me to have been all

alike in error.

The stuff of which the world of our experience is composed is, in

my belief, neither mind nor matter, but something more primitive

than either. Both mind and matter seem to be composite, and the

stuff of which they are compounded lies in a sense between the

two, in a sense above them both, like a common ancestor. As

regards matter, I have set forth my reasons for this view on

former occasions,* and I shall not now repeat them. But the

question of mind is more difficult, and it is this question that

I propose to discuss in these lectures. A great deal of what I

shall have to say is not original; indeed, much recent work, in

various fields, has tended to show the necessity of such theories

as those which I shall be advocating. Accordingly in this first

lecture I shall try to give a brief description of the systems of

ideas within which our investigation is to be carried on.

* "Our Knowledge of the External World" (Allen & Unwin), Chapters

III and IV. Also "Mysticism and Logic," Essays VII and VIII.

If there is one thing that may be said, in the popular

estimation, to characterize mind, that one thing is

"consciousness." We say that we are "conscious" of what we see

and hear, of what we remember, and of our own thoughts and

feelings. Most of us believe that tables and chairs are not

"conscious." We think that when we sit in a chair, we are aware

of sitting in it, but it is not aware of being sat in. It cannot

for a moment be doubted that we are right in believing that there

is SOME difference between us and the chair in this respect: so

much may be taken as fact, and as a datum for our inquiry. But as

soon as we try to say what exactly the difference is, we become

involved in perplexities. Is "consciousness" ultimate and simple,

something to be merely accepted and contemplated? Or is it

something complex, perhaps consisting in our way of behaving in

the presence of objects, or, alternatively, in the existence in

us of things called "ideas," having a certain relation to

objects, though different from them, and only symbolically

representative of them? Such questions are not easy to answer;

but until they are answered we cannot profess to know what we

mean by saying that we are possessed of "consciousness."

Before considering modern theories, let us look first at

consciousness from the standpoint of conventional psychology,

since this embodies views which naturally occur when we begin to

reflect upon the subject. For this purpose, let us as a

preliminary consider different ways of being conscious.

First, there is the way of PERCEPTION. We "perceive" tables and

chairs, horses and dogs, our friends, traffic passing in the

street--in short, anything which we recognize through the senses.

I leave on one side for the present the question whether pure

sensation is to be regarded as a form of consciousness: what I am

speaking of now is perception, where, according to conventional

psychology, we go beyond the sensation to the "thing" which it

represents. When you hear a donkey bray, you not only hear a

noise, but realize that it comes from a donkey. When you see a

table, you not only see a coloured surface, but realize that it

is hard. The addition of these elements that go beyond crude

sensation is said to constitute perception. We shall have more to

say about this at a later stage. For the moment, I am merely

concerned to note that perception of objects is one of the most

obvious examples of what is called "consciousness." We are

"conscious" of anything that we perceive.

We may take next the way of MEMORY. If I set to work to recall

what I did this morning, that is a form of consciousness

different from perception, since it is concerned with the past.

There are various problems as to how we can be conscious now of

what no longer exists. These will be dealt with incidentally when

we come to the analysis of memory.

From memory it is an easy step to what are called "ideas"--not in

the Platonic sense, but in that of Locke, Berkeley and Hume, in

which they are opposed to "impressions." You may be conscious of

a friend either by seeing him or by "thinking" of him; and by

"thought" you can be conscious of objects which cannot be seen,

such as the human race, or physiology. "Thought" in the narrower

sense is that form of consciousness which consists in "ideas" as

opposed to impressions or mere memories.

We may end our preliminary catalogue with BELIEF, by which I mean

that way of being conscious which may be either true or false. We

say that a man is "conscious of looking a fool," by which we mean

that he believes he looks a fool, and is not mistaken in this

belief. This is a different form of consciousness from any of the

earlier ones. It is the form which gives "knowledge" in the

strict sense, and also error. It is, at least apparently, more

complex than our previous forms of consciousness; though we shall

find that they are not so separable from it as they might appear

to be.

Besides ways of being conscious there are other things that would

ordinarily be called "mental," such as desire and pleasure and

pain. These raise problems of their own, which we shall reach in

Lecture III. But the hardest problems are those that arise

concerning ways of being "conscious." These ways, taken together,

are called the "cognitive" elements in mind, and it is these that

will occupy us most during the following lectures.

There is one element which SEEMS obviously in common among the

different ways of being conscious, and that is, that they are all

directed to OBJECTS. We are conscious "of" something. The

consciousness, it seems, is one thing, and that of which we are

conscious is another thing. Unless we are to acquiesce in the

view that we can never be conscious of anything outside our own

minds, we must say that the object of consciousness need not be

mental, though the consciousness must be. (I am speaking within

the circle of conventional doctrines, not expressing my own

beliefs.) This direction towards an object is commonly regarded

as typical of every form of cognition, and sometimes of mental

life altogether. We may distinguish two different tendencies in

traditional psychology. There are those who take mental phenomena

naively, just as they would physical phenomena. This school of

psychologists tends not to emphasize the object. On the other

hand, there are those whose primary interest is in the apparent

fact that we have KNOWLEDGE, that there is a world surrounding us

of which we are aware. These men are interested in the mind

because of its relation to the world, because knowledge, if it is

a fact, is a very mysterious one. Their interest in psychology is

naturally centred in the relation of consciousness to its object,

a problem which, properly, belongs rather to theory of knowledge.

We may take as one of the best and most typical representatives

of this school the Austrian psychologist Brentano, whose

"Psychology from the Empirical Standpoint,"* though published in

1874, is still influential and was the starting-point of a great

deal of interesting work. He says (p. 115):

* "Psychologie vom empirischen Standpunkte," vol. i, 1874. (The

second volume was never published.)

"Every psychical phenomenon is characterized by what the

scholastics of the Middle Ages called the intentional (also the

mental) inexistence of an object, and what we, although with not

quite unambiguous expressions, would call relation to a content,

direction towards an object (which is not here to be understood

as a reality), or immanent objectivity. Each contains something

in itself as an object, though not each in the same way. In

presentation something is presented, in judgment something is

acknowledged or rejected, in love something is loved, in hatred

hated, in desire desired, and so on.

"This intentional inexistence is exclusively peculiar to

psychical phenomena. No physical phenomenon shows anything

similar. And so we can define psychical phenomena by saying that

they are phenomena which intentionally contain an object in


The view here expressed, that relation to an object is an

ultimate irreducible characteristic of mental phenomena, is one

which I shall be concerned to combat. Like Brentano, I am

interested in psychology, not so much for its own sake, as for

the light that it may throw on the problem of knowledge. Until

very lately I believed, as he did, that mental phenomena have

essential reference to objects, except possibly in the case of

pleasure and pain. Now I no longer believe this, even in the case

of knowledge. I shall try to make my reasons for this rejection

clear as we proceed. It must be evident at first glance that the

analysis of knowledge is rendered more difficult by the

rejection; but the apparent simplicity of Brentano's view of

knowledge will be found, if I am not mistaken, incapable of

maintaining itself either against an analytic scrutiny or against

a host of facts in psycho-analysis and animal psychology. I do

not wish to minimize the problems. I will merely observe, in

mitigation of our prospective labours, that thinking, however it

is to be analysed, is in itself a delightful occupation, and that

there is no enemy to thinking so deadly as a false simplicity.

Travelling, whether in the mental or the physical world, is a

joy, and it is good to know that, in the mental world at least,

there are vast countries still very imperfectly explored.

The view expressed by Brentano has been held very generally, and

developed by many writers. Among these we may take as an example

his Austrian successor Meinong.* According to him there are three

elements involved in the thought of an object. These three he

calls the act, the content and the object. The act is the same in

any two cases of the same kind of consciousness; for instance, if

I think of Smith or think of Brown, the act of thinking, in

itself, is exactly similar on both occasions. But the content of

my thought, the particular event that is happening in my mind, is

different when I think of Smith and when I think of Brown. The

content, Meinong argues, must not be confounded with the object,

since the content must exist in my mind at the moment when I have

the thought, whereas the object need not do so. The object may be

something past or future; it may be physical, not mental; it may

be something abstract, like equality for example; it may be

something imaginary, like a golden mountain; or it may even be

something self-contradictory, like a round square. But in all

these cases, so he contends, the content exists when the thought

exists, and is what distinguishes it, as an occurrence, from

other thoughts.

* See, e.g. his article: "Ueber Gegenstande hoherer Ordnung und

deren Verhaltniss zur inneren Wahrnehmung," "Zeitschrift fur

Psychologie and Physiologie der Sinnesorgane," vol. xxi, pp.

182-272 (1899), especially pp. 185-8.

To make this theory concrete, let us suppose that you are

thinking of St. Paul's. Then, according to Meinong, we have to

distinguish three elements which are necessarily combined in

constituting the one thought. First, there is the act of

thinking, which would be just the same whatever you were thinking

about. Then there is what makes the character of the thought as

contrasted with other thoughts; this is the content. And finally

there is St. Paul's, which is the object of your thought. There

must be a difference between the content of a thought and what it

is about, since the thought is here and now, whereas what it is

about may not be; hence it is clear that the thought is not

identical with St. Paul's. This seems to show that we must

distinguish between content and object. But if Meinong is right,

there can be no thought without an object: the connection of the

two is essential. The object might exist without the thought, but

not the thought without the object: the three elements of act,

content and object are all required to constitute the one single

occurrence called "thinking of St. Paul's."

The above analysis of a thought, though I believe it to be

mistaken, is very useful as affording a schema in terms of which

other theories can be stated. In the remainder of the present

lecture I shall state in outline the view which I advocate, and

show how various other views out of which mine has grown result

from modifications of the threefold analysis into act, content

and object.

The first criticism I have to make is that the ACT seems

unnecessary and fictitious. The occurrence of the content of a

thought constitutes the occurrence of the thought. Empirically, I

cannot discover anything corresponding to the supposed act; and

theoretically I cannot see that it is indispensable. We say: "_I_

think so-and-so," and this word "I" suggests that thinking is the

act of a person. Meinong's "act" is the ghost of the subject, or

what once was the full-blooded soul. It is supposed that thoughts

cannot just come and go, but need a person to think them. Now, of

course it is true that thoughts can be collected into bundles, so

that one bundle is my thoughts, another is your thoughts, and a

third is the thoughts of Mr. Jones. But I think the person is not

an ingredient in the single thought: he is rather constituted by

relations of the thoughts to each other and to the body. This is

a large question, which need not, in its entirety, concern us at

present. All that I am concerned with for the moment is that the

grammatical forms "I think," "you think," and "Mr. Jones thinks,"

are misleading if regarded as indicating an analysis of a single

thought. It would be better to say "it thinks in me," like "it

rains here"; or better still, "there is a thought in me." This is

simply on the ground that what Meinong calls the act in thinking

is not empirically discoverable, or logically deducible from what

we can observe.

The next point of criticism concerns the relation of content and

object. The reference of thoughts to objects is not, I believe,

the simple direct essential thing that Brentano and Meinong

represent it as being. It seems to me to be derivative, and to

consist largely in BELIEFS: beliefs that what constitutes the

thought is connected with various other elements which together

make up the object. You have, say, an image of St. Paul's, or

merely the word "St. Paul's" in your head. You believe, however

vaguely and dimly, that this is connected with what you would see

if you went to St. Paul's, or what you would feel if you touched

its walls; it is further connected with what other people see and

feel, with services and the Dean and Chapter and Sir Christopher

Wren. These things are not mere thoughts of yours, but your

thought stands in a relation to them of which you are more or

less aware. The awareness of this relation is a further thought,

and constitutes your feeling that the original thought had an

"object." But in pure imagination you can get very similar

thoughts without these accompanying beliefs; and in this case

your thoughts do not have objects or seem to have them. Thus in

such instances you have content without object. On the other

hand, in seeing or hearing it would be less misleading to say

that you have object without content, since what you see or hear

is actually part of the physical world, though not matter in the

sense of physics. Thus the whole question of the relation of

mental occurrences to objects grows very complicated, and cannot

be settled by regarding reference to objects as of the essence of

thoughts. All the above remarks are merely preliminary, and will

be expanded later.

Speaking in popular and unphilosophical terms, we may say that

the content of a thought is supposed to be something in your head

when you think the thought, while the object is usually something

in the outer world. It is held that knowledge of the outer world

is constituted by the relation to the object, while the fact that

knowledge is different from what it knows is due to the fact that

knowledge comes by way of contents. We can begin to state the

difference between realism and idealism in terms of this

opposition of contents and objects. Speaking quite roughly and

approximately, we may say that idealism tends to suppress the

object, while realism tends to suppress the content. Idealism,

accordingly, says that nothing can be known except thoughts, and

all the reality that we know is mental; while realism maintains

that we know objects directly, in sensation certainly, and

perhaps also in memory and thought. Idealism does not say that

nothing can be known beyond the present thought, but it maintains

that the context of vague belief, which we spoke of in connection

with the thought of St. Paul's, only takes you to other thoughts,

never to anything radically different from thoughts. The

difficulty of this view is in regard to sensation, where it seems

as if we came into direct contact with the outer world. But the

Berkeleian way of meeting this difficulty is so familiar that I

need not enlarge upon it now. I shall return to it in a later

lecture, and will only observe, for the present, that there seem

to me no valid grounds for regarding what we see and hear as not

part of the physical world.

Realists, on the other hand, as a rule, suppress the content, and

maintain that a thought consists either of act and object alone,

or of object alone. I have been in the past a realist, and I

remain a realist as regards sensation, but not as regards memory

or thought. I will try to explain what seem to me to be the

reasons for and against various kinds of realism.

Modern idealism professes to be by no means confined to the

present thought or the present thinker in regard to its

knowledge; indeed, it contends that the world is so organic, so

dove-tailed, that from any one portion the whole can be inferred,

as the complete skeleton of an extinct animal can be inferred

from one bone. But the logic by which this supposed organic

nature of the world is nominally demonstrated appears to

realists, as it does to me, to be faulty. They argue that, if we

cannot know the physical world directly, we cannot really know

any thing outside our own minds: the rest of the world may be

merely our dream. This is a dreary view, and they there fore seek

ways of escaping from it. Accordingly they maintain that in

knowledge we are in direct contact with objects, which may be,

and usually are, outside our own minds. No doubt they are

prompted to this view, in the first place, by bias, namely, by

the desire to think that they can know of the existence of a

world outside themselves. But we have to consider, not what led

them to desire the view, but whether their arguments for it are


There are two different kinds of realism, according as we make a

thought consist of act and object, or of object alone. Their

difficulties are different, but neither seems tenable all

through. Take, for the sake of definiteness, the remembering of a

past event. The remembering occurs now, and is therefore

necessarily not identical with the past event. So long as we

retain the act, this need cause no difficulty. The act of

remembering occurs now, and has on this view a certain essential

relation to the past event which it remembers. There is no

LOGICAL objection to this theory, but there is the objection,

which we spoke of earlier, that the act seems mythical, and is

not to be found by observation. If, on the other hand, we try to

constitute memory without the act, we are driven to a content,

since we must have something that happens NOW, as opposed to the

event which happened in the past. Thus, when we reject the act,

which I think we must, we are driven to a theory of memory which

is more akin to idealism. These arguments, however, do not apply

to sensation. It is especially sensation, I think, which is

considered by those realists who retain only the object.* Their

views, which are chiefly held in America, are in large measure

derived from William James, and before going further it will be

well to consider the revolutionary doctrine which he advocated. I

believe this doctrine contains important new truth, and what I

shall have to say will be in a considerable measure inspired by


* This is explicitly the case with Mach's "Analysis of

Sensations," a book of fundamental importance in the present

connection. (Translation of fifth German edition, Open Court Co.,

1914. First German edition, 1886.)

William James's view was first set forth in an essay called "Does

'consciousness' exist?"* In this essay he explains how what used

to be the soul has gradually been refined down to the

"transcendental ego," which, he says, "attenuates itself to a

thoroughly ghostly condition, being only a name for the fact that

the 'content' of experience IS KNOWN. It loses personal form and

activity--these passing over to the content--and becomes a bare

Bewusstheit or Bewusstsein uberhaupt, of which in its own right

absolutely nothing can be said. I believe (he continues) that

'consciousness,' when once it has evaporated to this estate of

pure diaphaneity, is on the point of disappearing altogether. It

is the name of a nonentity, and has no right to a place among

first principles. Those who still cling to it are clinging to a

mere echo, the faint rumour left behind by the disappearing

'soul' upon the air of philosophy"(p. 2).

* "Journal of Philosophy, Psychology and Scientific Methods,"

vol. i, 1904. Reprinted in "Essays in Radical Empiricism"

(Longmans, Green & Co., 1912), pp. 1-38, to which references in

what follows refer.

He explains that this is no sudden change in his opinions. "For

twenty years past," he says, "I have mistrusted 'consciousness'

as an entity; for seven or eight years past I have suggested its

non-existence to my students, and tried to give them its

pragmatic equivalent in realities of experience. It seems to me

that the hour is ripe for it to be openly and universally

discarded"(p. 3).

His next concern is to explain away the air of paradox, for James

was never wilfully paradoxical. "Undeniably," he says,

"'thoughts' do exist." "I mean only to deny that the word stands

for an entity, but to insist most emphatically that it does stand

for a function. There is, I mean, no aboriginal stuff or quality

of being, contrasted with that of which material objects are

made, out of which our thoughts of them are made; but there is a

function in experience which thoughts perform, and for the

performance of which this quality of being is invoked. That

function is KNOWING"(pp. 3-4).

James's view is that the raw material out of which the world is

built up is not of two sorts, one matter and the other mind, but

that it is arranged in different patterns by its inter-relations,

and that some arrangements may be called mental, while others may

be called physical.

"My thesis is," he says, "that if we start with the supposition

that there is only one primal stuff or material in the world, a

stuff of which everything is composed, and if we call that stuff

'pure experience,' then knowing can easily be explained as a

particular sort of relation towards one another into which

portions of pure experience may enter. The relation itself is a

part of pure experience; one of its 'terms' becomes the subject

or bearer of the knowledge, the knower, the other becomes the

object known"(p. 4).

After mentioning the duality of subject and object, which is

supposed to constitute consciousness, he proceeds in italics:




He illustrates his meaning by the analogy of paint as it appears

in a paint-shop and as it appears in a picture: in the one case

it is just "saleable matter," while in the other it "performs a

spiritual function. Just so, I maintain (he continues), does a

given undivided portion of experience, taken in one context of

associates, play the part of a knower, of a state of mind, of

'consciousness'; while in a different context the same undivided

bit of experience plays the part of a thing known, of an

objective 'content.' In a word, in one group it figures as a

thought, in another group as a thing"(pp. 9-10).

He does not believe in the supposed immediate certainty of

thought. "Let the case be what it may in others," he says, "I am

as confident as I am of anything that, in myself, the stream of

thinking (which I recognize emphatically as a phenomenon) is only

a careless name for what, when scrutinized, reveals itself to

consist chiefly of the stream of my breathing. The 'I think'

which Kant said must be able to accompany all my objects, is the

'I breathe' which actually does accompany them"(pp. 36-37).

The same view of "consciousness" is set forth in the succeeding

essay, "A World of Pure Experience" (ib., pp. 39-91). The use of

the phrase "pure experience" in both essays points to a lingering

influence of idealism. "Experience," like "consciousness," must

be a product, not part of the primary stuff of the world. It must

be possible, if James is right in his main contentions, that

roughly the same stuff, differently arranged, would not give rise

to anything that could be called "experience." This word has been

dropped by the American realists, among whom we may mention

specially Professor R. B. Perry of Harvard and Mr. Edwin B. Holt.

The interests of this school are in general philosophy and the

philosophy of the sciences, rather than in psychology; they have

derived a strong impulsion from James, but have more interest

than he had in logic and mathematics and the abstract part of

philosophy. They speak of "neutral" entities as the stuff out of

which both mind and matter are constructed. Thus Holt says: "If

the terms and propositions of logic must be substantialized, they

are all strictly of one substance, for which perhaps the least

dangerous name is neutral- stuff. The relation of neutral-stuff

to matter and mind we shall have presently to consider at

considerable length." *

* "The Concept of Consciousness" (Geo. Allen & Co., 1914), p. 52.

My own belief--for which the reasons will appear in subsequent

lectures--is that James is right in rejecting consciousness as an

entity, and that the American realists are partly right, though

not wholly, in considering that both mind and matter are composed

of a neutral-stuff which, in isolation, is neither mental nor

material. I should admit this view as regards sensations: what is

heard or seen belongs equally to psychology and to physics. But I

should say that images belong only to the mental world, while

those occurrences (if any) which do not form part of any

"experience" belong only to the physical world. There are, it

seems to me, prima facie different kinds of causal laws, one

belonging to physics and the other to psychology. The law of

gravitation, for example, is a physical law, while the law of

association is a psychological law. Sensations are subject to

both kinds of laws, and are therefore truly "neutral" in Holt's

sense. But entities subject only to physical laws, or only to

psychological laws, are not neutral, and may be called

respectively purely material and purely mental. Even those,

however, which are purely mental will not have that intrinsic

reference to objects which Brentano assigns to them and which

constitutes the essence of "consciousness" as ordinarily

understood. But it is now time to pass on to other modern

tendencies, also hostile to "consciousness."

There is a psychological school called "Behaviourists," of whom

the protagonist is Professor John B. Watson,* formerly of the

Johns Hopkins University. To them also, on the whole, belongs

Professor John Dewey, who, with James and Dr. Schiller, was one

of the three founders of pragmatism. The view of the

"behaviourists" is that nothing can be known except by external

observation. They deny altogether that there is a separate source

of knowledge called "introspection," by which we can know things

about ourselves which we could never observe in others. They do

not by any means deny that all sorts of things MAY go on in our

minds: they only say that such things, if they occur, are not

susceptible of scientific observation, and do not therefore

concern psychology as a science. Psychology as a science, they

say, is only concerned with BEHAVIOUR, i.e. with what we DO; this

alone, they contend, can be accurately observed. Whether we think

meanwhile, they tell us, cannot be known; in their observation of

the behaviour of human beings, they have not so far found any

evidence of thought. True, we talk a great deal, and imagine that

in so doing we are showing that we can think; but behaviourists

say that the talk they have to listen to can be explained without

supposing that people think. Where you might expect a chapter on

"thought processes" you come instead upon a chapter on "The

Language Habit." It is humiliating to find how terribly adequate

this hypothesis turns out to be.

* See especially his "Behavior: an Introduction to Comparative

Psychology," New York, 1914.

Behaviourism has not, however, sprung from observing the folly of

men. It is the wisdom of animals that has suggested the view. It

has always been a common topic of popular discussion whether

animals "think." On this topic people are prepared to take sides

without having the vaguest idea what they mean by "thinking."

Those who desired to investigate such questions were led to

observe the behaviour of animals, in the hope that their

behaviour would throw some light on their mental faculties. At

first sight, it might seem that this is so. People say that a dog

"knows" its name because it comes when it is called, and that it

"remembers" its master, because it looks sad in his absence, but

wags its tail and barks when he returns. That the dog behaves in

this way is matter of observation, but that it "knows" or

"remembers" anything is an inference, and in fact a very doubtful

one. The more such inferences are examined, the more precarious

they are seen to be. Hence the study of animal behaviour has been

gradually led to abandon all attempt at mental interpretation.

And it can hardly be doubted that, in many cases of complicated

behaviour very well adapted to its ends, there can be no

prevision of those ends. The first time a bird builds a nest, we

can hardly suppose it knows that there will be eggs to be laid in

it, or that it will sit on the eggs, or that they will hatch into

young birds. It does what it does at each stage because instinct

gives it an impulse to do just that, not because it foresees and

desires the result of its actions.*

* An interesting discussion of the question whether instinctive

actions, when first performed, involve any prevision, however

vague, will be found in Lloyd Morgan's "Instinct and Experience"

(Methuen, 1912), chap. ii.

Careful observers of animals, being anxious to avoid precarious

inferences, have gradually discovered more and more how to give

an account of the actions of animals without assuming what we

call "consciousness." It has seemed to the behaviourists that

similar methods can be applied to human behaviour, without

assuming anything not open to external observation. Let us give a

crude illustration, too crude for the authors in question, but

capable of affording a rough insight into their meaning. Suppose

two children in a school, both of whom are asked "What is six

times nine?" One says fifty-four, the other says fifty-six. The

one, we say, "knows" what six times nine is, the other does not.

But all that we can observe is a certain language-habit. The one

child has acquired the habit of saying "six times nine is

fifty-four"; the other has not. There is no more need of

"thought" in this than there is when a horse turns into his

accustomed stable; there are merely more numerous and complicated

habits. There is obviously an observable fact called "knowing"

such-and-such a thing; examinations are experiments for

discovering such facts. But all that is observed or discovered is

a certain set of habits in the use of words. The thoughts (if

any) in the mind of the examinee are of no interest to the

examiner; nor has the examiner any reason to suppose even the

most successful examinee capable of even the smallest amount of


Thus what is called "knowing," in the sense in which we can

ascertain what other people "know," is a phenomenon exemplified

in their physical behaviour, including spoken and written words.

There is no reason--so Watson argues--to suppose that their

knowledge IS anything beyond the habits shown in this behaviour:

the inference that other people have something nonphysical called

"mind" or "thought" is therefore unwarranted.

So far, there is nothing particularly repugnant to our prejudices

in the conclusions of the behaviourists. We are all willing to

admit that other people are thoughtless. But when it comes to

ourselves, we feel convinced that we can actually perceive our

own thinking. "Cogito, ergo sum" would be regarded by most people

as having a true premiss. This, however, the behaviourist denies.

He maintains that our knowledge of ourselves is no different in

kind from our knowledge of other people. We may see MORE, because

our own body is easier to observe than that of other people; but

we do not see anything radically unlike what we see of others.

Introspection, as a separate source of knowledge, is entirely

denied by psychologists of this school. I shall discuss this

question at length in a later lecture; for the present I will

only observe that it is by no means simple, and that, though I

believe the behaviourists somewhat overstate their case, yet

there is an important element of truth in their contention, since

the things which we can discover by introspection do not seem to

differ in any very fundamental way from the things which we

discover by external observation.

So far, we have been principally concerned with knowing. But it

might well be maintained that desiring is what is really most

characteristic of mind. Human beings are constantly engaged in

achieving some end they feel pleasure in success and pain in

failure. In a purely material world, it may be said, there would

be no opposition of pleasant and unpleasant, good and bad, what

is desired and what is feared. A man's acts are governed by

purposes. He decides, let us suppose, to go to a certain place,

whereupon he proceeds to the station, takes his ticket and enters

the train. If the usual route is blocked by an accident, he goes

by some other route. All that he does is determined--or so it

seems--by the end he has in view, by what lies in front of him,

rather than by what lies behind. With dead matter, this is not

the case. A stone at the top of a hill may start rolling, but it

shows no pertinacity in trying to get to the bottom. Any ledge or

obstacle will stop it, and it will exhibit no signs of discontent

if this happens. It is not attracted by the pleasantness of the

valley, as a sheep or cow might be, but propelled by the

steepness of the hill at the place where it is. In all this we

have characteristic differences between the behaviour of animals

and the behaviour of matter as studied by physics.

Desire, like knowledge, is, of course, in one sense an observable

phenomenon. An elephant will eat a bun, but not a mutton chop; a

duck will go into the water, but a hen will not. But when we

think of our own. desires, most people believe that we can know

them by an immediate self-knowledge which does not depend upon

observation of our actions. Yet if this were the case, it would

be odd that people are so often mistaken as to what they desire.

It is matter of common observation that "so-and-so does not know

his own motives," or that "A is envious of B and malicious about

him, but quite unconscious of being so." Such people are called

self-deceivers, and are supposed to have had to go through some

more or less elaborate process of concealing from themselves what

would otherwise have been obvious. I believe that this is an

entire mistake. I believe that the discovery of our own motives

can only be made by the same process by which we discover other

people's, namely, the process of observing our actions and

inferring the desire which could prompt them. A desire is

"conscious" when we have told ourselves that we have it. A hungry

man may say to himself: "Oh, I do want my lunch." Then his desire

is "conscious." But it only differs from an "unconscious" desire

by the presence of appropriate words, which is by no means a

fundamental difference.

The belief that a motive is normally conscious makes it easier to

be mistaken as to our own motives than as to other people's. When

some desire that we should be ashamed of is attributed to us, we

notice that we have never had it consciously, in the sense of

saying to ourselves, "I wish that would happen." We therefore

look for some other interpretation of our actions, and regard our

friends as very unjust when they refuse to be convinced by our

repudiation of what we hold to be a calumny. Moral considerations

greatly increase the difficulty of clear thinking in this matter.

It is commonly argued that people are not to blame for

unconscious motives, but only for conscious ones. In order,

therefore, to be wholly virtuous it is only necessary to repeat

virtuous formulas. We say: "I desire to be kind to my friends,

honourable in business, philanthropic towards the poor,

public-spirited in politics." So long as we refuse to allow

ourselves, even in the watches of the night, to avow any contrary

desires, we may be bullies at home, shady in the City, skinflints

in paying wages and profiteers in dealing with the public; yet,

if only conscious motives are to count in moral valuation, we

shall remain model characters. This is an agreeable doctrine, and

it is not surprising that men are un willing to abandon it. But

moral considerations are the worst enemies of the scientific

spirit and we must dismiss them from our minds if we wish to

arrive at truth.

I believe--as I shall try to prove in a later lecture -that

desire, like force in mechanics, is of the nature of a convenient

fiction for describing shortly certain laws of behaviour. A

hungry animal is restless until it finds food; then it becomes

quiescent. The thing which will bring a restless condition to an

end is said to be what is desired. But only experience can show

what will have this sedative effect, and it is easy to make

mistakes. We feel dissatisfaction, and think that such and-such a

thing would remove it; but in thinking this, we are theorizing,

not observing a patent fact. Our theorizing is often mistaken,

and when it is mistaken there is a difference between what we

think we desire and what in fact will bring satisfaction. This is

such a common phenomenon that any theory of desire which fails to

account for it must be wrong.

What have been called "unconscious" desires have been brought

very much to the fore in recent years by psycho-analysis.

Psycho-analysis, as every one knows, is primarily a method of

understanding hysteria and certain forms of insanity*; but it has

been found that there is much in the lives of ordinary men and

women which bears a humiliating resemblance to the delusions of

the insane. The connection of dreams, irrational beliefs and

foolish actions with unconscious wishes has been brought to

light, though with some exaggeration, by Freud and Jung and their

followers. As regards the nature of these unconscious wishes, it

seems to me--though as a layman I speak with diffidence--that

many psycho-analysts are unduly narrow; no doubt the wishes they

emphasize exist, but others, e.g. for honour and power, are

equally operative and equally liable to concealment. This,

however, does not affect the value of their general theories from

the point of view of theoretic psychology, and it is from this

point of view that their results are important for the analysis

of mind.

* There is a wide field of "unconscious" phenomena which does not

depend upon psycho-analytic theories. Such occurrences as

automatic writing lead Dr. Morton Prince to say: "As I view this

question of the subconscious, far too much weight is given to the

point of awareness or not awareness of our conscious processes.

As a matter of fact, we find entirely identical phenomena, that

is, identical in every respect but one-that of awareness in which

sometimes we are aware of these conscious phenomena and sometimes

not"(p. 87 of "Subconscious Phenomena," by various authors,

Rebman). Dr. Morton Price conceives that there may be

"consciousness" without "awareness." But this is a difficult

view, and one which makes some definition of "consciousness"

imperative. For nay part, I cannot see how to separate

consciousness from awareness.

What, I think, is clearly established, is that a man's actions

and beliefs may be wholly dominated by a desire of which he is

quite unconscious, and which he indignantly repudiates when it is

suggested to him. Such a desire is generally, in morbid cases, of

a sort which the patient would consider wicked; if he had to

admit that he had the desire, he would loathe himself. Yet it is

so strong that it must force an outlet for itself; hence it

becomes necessary to entertain whole systems of false beliefs in

order to hide the nature of what is desired. The resulting

delusions in very many cases disappear if the hysteric or lunatic

can be made to face the facts about himself. The consequence of

this is that the treatment of many forms of insanity has grown

more psychological and less physiological than it used to be.

Instead of looking for a physical defect in the brain, those who

treat delusions look for the repressed desire which has found

this contorted mode of expression. For those who do not wish to

plunge into the somewhat repulsive and often rather wild theories

of psychoanalytic pioneers, it will be worth while to read a

little book by Dr. Bernard Hart on "The Psychology of Insanity."*

On this question of the mental as opposed to the physiological

study of the causes of insanity, Dr. Hart says:

* Cambridge, 1912; 2nd edition, 1914. The following references

are to the second edition.

"The psychological conception [of insanity] is based on the view

that mental processes can be directly studied without any

reference to the accompanying changes which are presumed to take

place in the brain, and that insanity may therefore be properly

attacked from the standpoint of psychology"(p. 9).

This illustrates a point which I am anxious to make clear from

the outset. Any attempt to classify modern views, such as I

propose to advocate, from the old standpoint of materialism and

idealism, is only misleading. In certain respects, the views

which I shall be setting forth approximate to materialism; in

certain others, they approximate to its opposite. On this

question of the study of delusions, the practical effect of the

modern theories, as Dr. Hart points out, is emancipation from the

materialist method. On the other hand, as he also points out (pp.

38-9), imbecility and dementia still have to be considered

physiologically, as caused by defects in the brain. There is no

inconsistency in this If, as we maintain, mind and matter are

neither of them the actual stuff of reality, but different

convenient groupings of an underlying material, then, clearly,

the question whether, in regard to a given phenomenon, we are to

seek a physical or a mental cause, is merely one to be decided by

trial. Metaphysicians have argued endlessly as to the interaction

of mind and matter. The followers of Descartes held that mind and

matter are so different as to make any action of the one on the

other impossible. When I will to move my arm, they said, it is

not my will that operates on my arm, but God, who, by His

omnipotence, moves my arm whenever I want it moved. The modern

doctrine of psychophysical parallelism is not appreciably

different from this theory of the Cartesian school.

Psycho-physical parallelism is the theory that mental and

physical events each have causes in their own sphere, but run on

side by side owing to the fact that every state of the brain

coexists with a definite state of the mind, and vice versa. This

view of the reciprocal causal independence of mind and matter has

no basis except in metaphysical theory.* For us, there is no

necessity to make any such assumption, which is very difficult to

harmonize with obvious facts. I receive a letter inviting me to

dinner: the letter is a physical fact, but my apprehension of its

meaning is mental. Here we have an effect of matter on mind. In

consequence of my apprehension of the meaning of the letter, I go

to the right place at the right time; here we have an effect of

mind on matter. I shall try to persuade you, in the course of

these lectures, that matter is not so material and mind not so

mental as is generally supposed. When we are speaking of matter,

it will seem as if we were inclining to idealism; when we are

speaking of mind, it will seem as if we were inclining to

materialism. Neither is the truth. Our world is to be constructed

out of what the American realists call "neutral" entities, which

have neither the hardness and indestructibility of matter, nor

the reference to objects which is supposed to characterize mind.

* It would seem, however, that Dr. Hart accepts this theory as 8

methodological precept. See his contribution to "Subconscious

Phenomena" (quoted above), especially pp. 121-2.

There is, it is true, one objection which might be felt, not

indeed to the action of matter on mind, but to the action of mind

on matter. The laws of physics, it may be urged, are apparently

adequate to explain everything that happens to matter, even when

it is matter in a man's brain. This, however, is only a

hypothesis, not an established theory. There is no cogent

empirical reason for supposing that the laws determining the

motions of living bodies are exactly the same as those that apply

to dead matter. Sometimes, of course, they are clearly the same.

When a man falls from a precipice or slips on a piece of orange

peel, his body behaves as if it were devoid of life. These are

the occasions that make Bergson laugh. But when a man's bodily

movements are what we call "voluntary," they are, at any rate

prima facie, very different in their laws from the movements of

what is devoid of life. I do not wish to say dogmatically that

the difference is irreducible; I think it highly probable that it

is not. I say only that the study of the behaviour of living

bodies, in the present state of our knowledge, is distinct from

physics. The study of gases was originally quite distinct from

that of rigid bodies, and would never have advanced to its

present state if it had not been independently pursued. Nowadays

both the gas and the rigid body are manufactured out of a more

primitive and universal kind of matter. In like manner, as a

question of methodology, the laws of living bodies are to be

studied, in the first place, without any undue haste to

subordinate them to the laws of physics. Boyle's law and the rest

had to be discovered before the kinetic theory of gases became

possible. But in psychology we are hardly yet at the stage of

Boyle's law. Meanwhile we need not be held up by the bogey of the

universal rigid exactness of physics. This is, as yet, a mere

hypothesis, to be tested empirically without any preconceptions.

It may be true, or it may not. So far, that is all we can say.

Returning from this digression to our main topic, namely, the

criticism of "consciousness," we observe that Freud and his

followers, though they have demonstrated beyond dispute the

immense importance of "unconscious" desires in determining our

actions and beliefs, have not attempted the task of telling us

what an "unconscious" desire actually is, and have thus invested

their doctrine with an air of mystery and mythology which forms a

large part of its popular attractiveness. They speak always as

though it were more normal for a desire to be conscious, and as

though a positive cause had to be assigned for its being

unconscious. Thus "the unconscious" becomes a sort of underground

prisoner, living in a dungeon, breaking in at long intervals upon

our daylight respectability with dark groans and maledictions and

strange atavistic lusts. The ordinary reader, almost inevitably,

thinks of this underground person as another consciousness,

prevented by what Freud calls the "censor" from making his voice

heard in company, except on rare and dreadful occasions when he

shouts so loud that every one hears him and there is a scandal.

Most of us like the idea that we could be desperately wicked if

only we let ourselves go. For this reason, the Freudian

"unconscious" has been a consolation to many quiet and

well-behaved persons.

I do not think the truth is quite so picturesque as this. I

believe an "unconscious" desire is merely a causal law of our

behaviour,* namely, that we remain restlessly active until a

certain state of affairs is realized, when we achieve temporary

equilibrium If we know beforehand what this state of affairs is,

our desire is conscious; if not, unconscious. The unconscious

desire is not something actually existing, but merely a tendency

to a certain behaviour; it has exactly the same status as a force

in dynamics. The unconscious desire is in no way mysterious; it

is the natural primitive form of desire, from which the other has

developed through our habit of observing and theorizing (often

wrongly). It is not necessary to suppose, as Freud seems to do,

that every unconscious wish was once conscious, and was then, in

his terminology, "repressed" because we disapproved of it. On the

contrary, we shall suppose that, although Freudian "repression"

undoubtedly occurs and is important, it is not the usual reason

for unconsciousness of our wishes. The usual reason is merely

that wishes are all, to begin with, unconscious, and only become

known when they are actively noticed. Usually, from laziness,

people do not notice, but accept the theory of human nature which

they find current, and attribute to themselves whatever wishes

this theory would lead them to expect. We used to be full of

virtuous wishes, but since Freud our wishes have become, in the

words of the Prophet Jeremiah, "deceitful above all things and

desperately wicked." Both these views, in most of those who have

held them, are the product of theory rather than observation, for

observation requires effort, whereas repeating phrases does not.

* Cf. Hart, "The Psychology of Insanity," p. 19.

The interpretation of unconscious wishes which I have been

advocating has been set forth briefly by Professor John B. Watson

in an article called "The Psychology of Wish Fulfilment," which

appeared in "The Scientific Monthly" in November, 1916. Two

quotations will serve to show his point of view:

"The Freudians (he says) have made more or less of a

'metaphysical entity' out of the censor. They suppose that when

wishes are repressed they are repressed into the 'unconscious,'

and that this mysterious censor stands at the trapdoor lying

between the conscious and the unconscious. Many of us do not

believe in a world of the unconscious (a few of us even have

grave doubts about the usefulness of the term consciousness),

hence we try to explain censorship along ordinary biological

lines. We believe that one group of habits can 'down' another

group of habits--or instincts. In this case our ordinary system

of habits--those which we call expressive of our 'real selves'--

inhibit or quench (keep inactive or partially inactive) those

habits and instinctive tendencies which belong largely in the

past"(p. 483).

Again, after speaking of the frustration of some impulses which

is involved in acquiring the habits of a civilized adult, he


"It is among these frustrated impulses that I would find the

biological basis of the unfulfilled wish. Such 'wishes' need

never have been 'conscious,' and NEED NEVER HAVE BEEN SUPPRESSED


this that there is no particular reason for applying the term

'wish' to such tendencies"(p. 485).

One of the merits of the general analysis of mind which we shall

be concerned with in the following lectures is that it removes

the atmosphere of mystery from the phenomena brought to light by

the psycho-analysts. Mystery is delightful, but unscientific,

since it depends upon ignorance. Man has developed out of the

animals, and there is no serious gap between him and the amoeba.

Something closely analogous to knowledge and desire, as regards

its effects on behaviour, exists among animals, even where what

we call "consciousness" is hard to believe in; something equally

analogous exists in ourselves in cases where no trace of

"consciousness" can be found. It is therefore natural to suppose

that, what ever may be the correct definition of "consciousness,"

"consciousness" is not the essence of life or mind. In the

following lectures, accordingly, this term will disappear until

we have dealt with words, when it will re-emerge as mainly a

trivial and unimportant outcome of linguistic habits.


In attempting to understand the elements out of which mental

phenomena are compounded, it is of the greatest importance to

remember that from the protozoa to man there is nowhere a very

wide gap either in structure or in behaviour. From this fact it

is a highly probable inference that there is also nowhere a very

wide mental gap. It is, of course, POSSIBLE that there may be, at

certain stages in evolution, elements which are entirely new from

the standpoint of analysis, though in their nascent form they

have little influence on behaviour and no very marked

correlatives in structure. But the hypothesis of continuity in

mental development is clearly preferable if no psychological

facts make it impossible. We shall find, if I am not mistaken,

that there are no facts which refute the hypothesis of mental

continuity, and that, on the other hand, this hypothesis affords

a useful test of suggested theories as to the nature of mind.

The hypothesis of mental continuity throughout organic evolution

may be used in two different ways. On the one hand, it may be

held that we have more knowledge of our own minds than those of

animals, and that we should use this knowledge to infer the

existence of something similar to our own mental processes in

animals and even in plants. On the other hand, it may be held

that animals and plants present simpler phenomena, more easily

analysed than those of human minds; on this ground it may be

urged that explanations which are adequate in the case of animals

ought not to be lightly rejected in the case of man. The

practical effects of these two views are diametrically opposite:

the first leads us to level up animal intelligence with what we

believe ourselves to know about our own intelligence, while the

second leads us to attempt a levelling down of our own

intelligence to something not too remote from what we can observe

in animals. It is therefore important to consider the relative

justification of the two ways of applying the principle of


It is clear that the question turns upon another, namely, which

can we know best, the psychology of animals or that of human

beings? If we can know most about animals, we shall use this

knowledge as a basis for inference about human beings; if we can

know most about human beings, we shall adopt the opposite

procedure. And the question whether we can know most about the

psychology of human beings or about that of animals turns upon

yet another, namely: Is introspection or external observation the

surer method in psychology? This is a question which I propose to

discuss at length in Lecture VI; I shall therefore content myself

now with a statement of the conclusions to be arrived at.

We know a great many things concerning ourselves which we cannot

know nearly so directly concerning animals or even other people.

We know when we have a toothache, what we are thinking of, what

dreams we have when we are asleep, and a host of other

occurrences which we only know about others when they tell us of

them, or otherwise make them inferable by their behaviour. Thus,

so far as knowledge of detached facts is concerned, the advantage

is on the side of self-knowledge as against external observation.

But when we come to the analysis and scientific understanding of

the facts, the advantages on the side of self-knowledge become

far less clear. We know, for example, that we have desires and

beliefs, but we do not know what constitutes a desire or a

belief. The phenomena are so familiar that it is difficult to

realize how little we really know about them. We see in animals,

and to a lesser extent in plants, behaviour more or less similar

to that which, in us, is prompted by desires and beliefs, and we

find that, as we descend in the scale of evolution, behaviour

becomes simpler, more easily reducible to rule, more

scientifically analysable and predictable. And just because we

are not misled by familiarity we find it easier to be cautious in

interpreting behaviour when we are dealing with phenomena remote

from those of our own minds: Moreover, introspection, as

psychoanalysis has demonstrated, is extraordinarily fallible even

in cases where we feel a high degree of certainty. The net result

seems to be that, though self-knowledge has a definite and

important contribution to make to psychology, it is exceedingly

misleading unless it is constantly checked and controlled by the

test of external observation, and by the theories which such

observation suggests when applied to animal behaviour. On the

whole, therefore, there is probably more to be learnt about human

psychology from animals than about animal psychology from human

beings; but this conclusion is one of degree, and must not be

pressed beyond a point.

It is only bodily phenomena that can be directly observed in

animals, or even, strictly speaking, in other human beings. We

can observe such things as their movements, their physiological

processes, and the sounds they emit. Such things as desires and

beliefs, which seem obvious to introspection, are not visible

directly to external observation. Accordingly, if we begin our

study of psychology by external observation, we must not begin by

assuming such things as desires and beliefs, but only such things

as external observation can reveal, which will be characteristics

of the movements and physiological processes of animals. Some

animals, for example, always run away from light and hide

themselves in dark places. If you pick up a mossy stone which is

lightly embedded in the earth, you will see a number of small

animals scuttling away from the unwonted daylight and seeking

again the darkness of which you have deprived them. Such animals

are sensitive to light, in the sense that their movements are

affected by it; but it would be rash to infer that they have

sensations in any way analogous to our sensations of sight. Such

inferences, which go beyond the observable facts, are to be

avoided with the utmost care.

It is customary to divide human movements into three classes,

voluntary, reflex and mechanical. We may illustrate the

distinction by a quotation from William James ("Psychology," i,


"If I hear the conductor calling 'all aboard' as I enter the

depot, my heart first stops, then palpitates, and my legs respond

to the air-waves falling on my tympanum by quickening their

movements. If I stumble as I run, the sensation of falling

provokes a movement of the hands towards the direction of the

fall, the effect of which is to shield the body from too sudden a

shock. If a cinder enter my eye, its lids close forcibly and a

copious flow of tears tends to wash it out.

"These three responses to a sensational stimulus differ, however,

in many respects. The closure of the eye and the lachrymation are

quite involuntary, and so is the disturbance of the heart. Such

involuntary responses we know as 'reflex' acts. The motion of the

arms to break the shock of falling may also be called reflex,

since it occurs too quickly to be deliberately intended. Whether

it be instinctive or whether it result from the pedestrian

education of childhood may be doubtful; it is, at any rate, less

automatic than the previous acts, for a man might by conscious

effort learn to perform it more skilfully, or even to suppress it

altogether. Actions of this kind, with which instinct and

volition enter upon equal terms, have been called 'semi-reflex.'

The act of running towards the train, on the other hand, has no

instinctive element about it. It is purely the result of

education, and is preceded by a consciousness of the purpose to

be attained and a distinct mandate of the will. It is a

'voluntary act.' Thus the animal's reflex and voluntary

performances shade into each other gradually, being connected by

acts which may often occur automatically, but may also be

modified by conscious intelligence.

"An outside observer, unable to perceive the accompanying

consciousness, might be wholly at a loss to discriminate between

the automatic acts and those which volition escorted. But if the

criterion of mind's existence be the choice of the proper means

for the attainment of a supposed end, all the acts alike seem to

be inspired by intelligence, for APPROPRIATENESS characterizes

them all alike. "

There is one movement, among those that James mentions at first,

which is not subsequently classified, namely, the stumbling. This

is the kind of movement which may be called "mechanical"; it is

evidently of a different kind from either reflex or voluntary

movements, and more akin to the movements of dead matter. We may

define a movement of an animal's body as "mechanical" when it

proceeds as if only dead matter were involved. For example, if

you fall over a cliff, you move under the influence of

gravitation, and your centre of gravity describes just as correct

a parabola as if you were already dead. Mechanical movements have

not the characteristic of appropriateness, unless by accident, as

when a drunken man falls into a waterbutt and is sobered. But

reflex and voluntary movements are not ALWAYS appropriate, unless

in some very recondite sense. A moth flying into a lamp is not

acting sensibly; no more is a man who is in such a hurry to get

his ticket that he cannot remember the name of his destination.

Appropriateness is a complicated and merely approximate idea, and

for the present we shall do well to dismiss it from our thoughts.

As James states, there is no difference, from the point of view

of the outside observer, between voluntary and reflex movements.

The physiologist can discover that both depend upon the nervous

system, and he may find that the movements which we call

voluntary depend upon higher centres in the brain than those that

are reflex. But he cannot discover anything as to the presence or

absence of "will" or "consciousness," for these things can only

be seen from within, if at all. For the present, we wish to place

ourselves resolutely in the position of outside observers; we

will therefore ignore the distinction between voluntary and

reflex movements. We will call the two together "vital"

movements. We may then distinguish "vital" from mechanical

movements by the fact that vital movements depend for their

causation upon the special properties of the nervous system,

while mechanical movements depend only upon the properties which

animal bodies share with matter in general.

There is need for some care if the distinction between mechanical

and vital movements is to be made precise. It is quite likely

that, if we knew more about animal bodies, we could deduce all

their movements from the laws of chemistry and physics. It is

already fairly easy to see how chemistry reduces to physics, i.e.

how the differences between different chemical elements can be

accounted for by differences of physical structure, the

constituents of the structure being electrons which are exactly

alike in all kinds of matter. We only know in part how to reduce

physiology to chemistry, but we know enough to make it likely

that the reduction is possible. If we suppose it effected, what

would become of the difference between vital and mechanical


Some analogies will make the difference clear. A shock to a mass

of dynamite produces quite different effects from an equal shock

to a mass of steel: in the one case there is a vast explosion,

while in the other case there is hardly any noticeable

disturbance. Similarly, you may sometimes find on a mountain-side

a large rock poised so delicately that a touch will set it

crashing down into the valley, while the rocks all round are so

firm that only a considerable force can dislodge them What is

analogous in these two cases is the existence of a great store of

energy in unstable equilibrium ready to burst into violent motion

by the addition of a very slight disturbance. Similarly, it

requires only a very slight expenditure of energy to send a

post-card with the words "All is discovered; fly!" but the effect

in generating kinetic energy is said to be amazing. A human body,

like a mass of dynamite, contains a store of energy in unstable

equilibrium, ready to be directed in this direction or that by a

disturbance which is physically very small, such as a spoken

word. In all such cases the reduction of behaviour to physical

laws can only be effected by entering into great minuteness; so

long as we confine ourselves to the observation of comparatively

large masses, the way in which the equilibrium will be upset

cannot be determined. Physicists distinguish between macroscopic

and microscopic equations: the former determine the visible

movements of bodies of ordinary size, the latter the minute

occurrences in the smallest parts. It is only the microscopic

equations that are supposed to be the same for all sorts of

matter. The macroscopic equations result from a process of

averaging out, and may be different in different cases. So, in

our instance, the laws of macroscopic phenomena are different for

mechanical and vital movements, though the laws of microscopic

phenomena may be the same.

We may say, speaking somewhat roughly, that a stimulus applied to

the nervous system, like a spark to dynamite, is able to take

advantage of the stored energy in unstable equilibrium, and thus

to produce movements out of proportion to the proximate cause.

Movements produced in this way are vital movements, while

mechanical movements are those in which the stored energy of a

living body is not involved. Similarly dynamite may be exploded,

thereby displaying its characteristic properties, or may (with

due precautions) be carted about like any other mineral. The

explosion is analogous to vital movements, the carting about to

mechanical movements.

Mechanical movements are of no interest to the psychologist, and

it has only been necessary to define them in order to be able to

exclude them. When a psychologist studies behaviour, it is only

vital movements that concern him. We shall, therefore, proceed to

ignore mechanical movements, and study only the properties of the


The next point is to distinguish between movements that are

instinctive and movements that are acquired by experience. This

distinction also is to some extent one of degree. Professor Lloyd

Morgan gives the following definition of "instinctive behaviour":

"That which is, on its first occurrence, independent of prior

experience; which tends to the well-being of the individual and

the preservation of the race; which is similarly performed by all

members of the same more or less restricted group of animals; and

which may be subject to subsequent modification under the

guidance of experience." *

* "Instinct and Experience" (Methuen, 1912) p. 5.

This definition is framed for the purposes of biology, and is in

some respects unsuited to the needs of psychology. Though perhaps

unavoidable, allusion to "the same more or less restricted group

of animals" makes it impossible to judge what is instinctive in

the behaviour of an isolated individual. Moreover, "the

well-being of the individual and the preservation of the race" is

only a usual characteristic, not a universal one, of the sort of

movements that, from our point of view, are to be called

instinctive; instances of harmful instincts will be given

shortly. The essential point of the definition, from our point of

view, is that an instinctive movement is in dependent of prior


We may say that an "instinctive" movement is a vital movement

performed by an animal the first time that it finds itself in a

novel situation; or, more correctly, one which it would perform

if the situation were novel.* The instincts of an animal are

different at different periods of its growth, and this fact may

cause changes of behaviour which are not due to learning. The

maturing and seasonal fluctuation of the sex-instinct affords a

good illustration. When the sex-instinct first matures, the

behaviour of an animal in the presence of a mate is different

from its previous behaviour in similar circumstances, but is not

learnt, since it is just the same if the animal has never

previously been in the presence of a mate.

* Though this can only be decided by comparison with other

members of the species, and thus exposes us to the need of

comparison which we thought an objection to Professor Lloyd

Morgan's definition.

On the other hand, a movement is "learnt," or embodies a "habit,"

if it is due to previous experience of similar situations, and is

not what it would be if the animal had had no such experience.

There are various complications which blur the sharpness of this

distinction in practice. To begin with, many instincts mature

gradually, and while they are immature an animal may act in a

fumbling manner which is very difficult to distinguish from

learning. James ("Psychology," ii, 407) maintains that children

walk by instinct, and that the awkwardness of their first

attempts is only due to the fact that the instinct has not yet

ripened. He hopes that "some scientific widower, left alone with

his offspring at the critical moment, may ere long test this

suggestion on the living subject." However this may be, he quotes

evidence to show that "birds do not LEARN to fly," but fly by

instinct when they reach the appropriate age (ib., p. 406). In

the second place, instinct often gives only a rough outline of

the sort of thing to do, in which case learning is necessary in

order to acquire certainty and precision in action. In the third

place, even in the clearest cases of acquired habit, such as

speaking, some instinct is required to set in motion the process

of learning. In the case of speaking, the chief instinct involved

is commonly supposed to be that of imitation, but this may be

questioned. (See Thorndike's "Animal Intelligence," p. 253 ff.)

In spite of these qualifications, the broad distinction between

instinct and habit is undeniable. To take extreme cases, every

animal at birth can take food by instinct, before it has had

opportunity to learn; on the other hand, no one can ride a

bicycle by instinct, though, after learning, the necessary

movements become just as automatic as if they were instinctive.

The process of learning, which consists in the acquisition of

habits, has been much studied in various animals.* For example:

you put a hungry animal, say a cat, in a cage which has a door

that can be opened by lifting a latch; outside the cage you put

food. The cat at first dashes all round the cage, making frantic

efforts to force a way out. At last, by accident, the latch is

lifted. and the cat pounces on the food. Next day you repeat the

experiment, and you find that the cat gets out much more quickly

than the first time, although it still makes some random

movements. The third day it gets out still more quickly, and

before long it goes straight to the latch and lifts it at once.

Or you make a model of the Hampton Court maze, and put a rat in

the middle, assaulted by the smell of food on the outside. The

rat starts running down the passages, and is constantly stopped

by blind alleys, but at last, by persistent attempts, it gets

out. You repeat this experiment day after day; you measure the

time taken by the rat in reaching the food; you find that the

time rapidly diminishes, and that after a while the rat ceases to

make any wrong turnings. It is by essentially similar processes

that we learn speaking, writing, mathematics, or the government

of an empire.

* The scientific study of this subject may almost be said to

begin with Thorndike's "Animal Intelligence" (Macmillan, 1911).

Professor Watson ("Behavior," pp. 262-3) has an ingenious theory

as to the way in which habit arises out of random movements. I

think there is a reason why his theory cannot be regarded as

alone sufficient, but it seems not unlikely that it is partly

correct. Suppose, for the sake of simplicity, that there are just

ten random movements which may be made by the animal--say, ten

paths down which it may go--and that only one of these leads to

food, or whatever else represents success in the case in

question. Then the successful movement always occurs during the

animal's attempts, whereas each of the others, on the average,

occurs in only half the attempts. Thus the tendency to repeat a

previous performance (which is easily explicable without the

intervention of "consciousness") leads to a greater emphasis on

the successful movement than on any other, and in time causes it

alone to be performed. The objection to this view, if taken as

the sole explanation, is that on improvement ought to set in till

after the SECOND trial, whereas experiment shows that already at

the second attempt the animal does better than the first time.

Something further is, therefore, required to account for the

genesis of habit from random movements; but I see no reason to

suppose that what is further required involves "consciousness."

Mr. Thorndike (op. cit., p. 244) formulates two "provisional laws

of acquired behaviour or learning," as follows:

"The Law of Effect is that: Of several responses made to the same

situation, those which are accompanied or closely followed by

satisfaction to the animal will, other things being equal, be

more firmly connected with the situation, so that, when it

recurs, they will be more likely to recur; those which are

accompanied or closely followed by discomfort to the animal will,

other things being equal, have their connections with that

situation weakened, so that, when it recurs, they will be less

likely to occur. The greater the satisfaction or discomfort, the

greater the strengthening or weakening of the bond.

"The Law of Exercise is that: Any response to a situation will,

other things being equal, be more strongly connected with the

situation in proportion to the number of times it has been

connected with that situation and to the average vigour and

duration of the connections."

With the explanation to be presently given of the meaning of

"satisfaction" and "discomfort," there seems every reason to

accept these two laws.

What is true of animals, as regards instinct and habit, is

equally true of men. But the higher we rise in the evolutionary

scale, broadly speaking, the greater becomes the power of

learning, and the fewer are the occasions when pure instinct is

exhibited unmodified in adult life. This applies with great force

to man, so much so that some have thought instinct less important

in the life of man than in that of animals. This, however, would

be a mistake. Learning is only possible when instinct supplies

the driving-force. The animals in cages, which gradually learn to

get out, perform random movements at first, which are purely

instinctive. But for these random movements, they would never

acquire the experience which afterwards enables them to produce

the right movement. (This is partly questioned by Hobhouse*--

wrongly, I think.) Similarly, children learning to talk make all

sorts of sounds, until one day the right sound comes by accident.

It is clear that the original making of random sounds, without

which speech would never be learnt, is instinctive. I think we

may say the same of all the habits and aptitudes that we acquire

in all of them there has been present throughout some instinctive

activity, prompting at first rather inefficient movements, but

supplying the driving force while more and more effective methods

are being acquired. A cat which is hungry smells fish, and goes

to the larder. This is a thoroughly efficient method when there

is fish in the larder, and it is often successfully practised by

children. But in later life it is found that merely going to the

larder does not cause fish to be there; after a series of random

movements it is found that this result is to be caused by going

to the City in the morning and coming back in the evening. No one

would have guessed a priori that this movement of a middle-aged

man's body would cause fish to come out of the sea into his

larder, but experience shows that it does, and the middle-aged

man therefore continues to go to the City, just as the cat in the

cage continues to lift the latch when it has once found it. Of

course, in actual fact, human learning is rendered easier, though

psychologically more complex, through language; but at bottom

language does not alter the essential character of learning, or

of the part played by instinct in promoting learning. Language,

however, is a subject upon which I do not wish to speak until a

later lecture.

* "Mind in Evolution" (Macmillan, 1915), pp. 236-237.

The popular conception of instinct errs by imagining it to be

infallible and preternaturally wise, as well as incapable of

modification. This is a complete delusion. Instinct, as a rule,

is very rough and ready, able to achieve its result under

ordinary circumstances, but easily misled by anything unusual.

Chicks follow their mother by instinct, but when they are quite

young they will follow with equal readiness any moving object

remotely resembling their mother, or even a human being (James,

"Psychology," ii, 396). Bergson, quoting Fabre, has made play

with the supposed extraordinary accuracy of the solitary wasp

Ammophila, which lays its eggs in a caterpillar. On this subject

I will quote from Drever's "Instinct in Man," p. 92:

"According to Fabre's observations, which Bergson accepts, the

Ammophila stings its prey EXACTLY and UNERRINGLY in EACH of the

nervous centres. The result is that the caterpillar is paralyzed,

but not immediately killed, the advantage of this being that the

larva cannot be injured by any movement of the caterpillar, upon

which the egg is deposited, and is provided with fresh meat when

the time comes.

"Now Dr. and Mrs. Peckham have shown that the sting of the wasp

is NOT UNERRING, as Fabre alleges, that the number of stings is

NOT CONSTANT, that sometimes the caterpillar is NOT PARALYZED,

and sometimes it is KILLED OUTRIGHT, and that THE DIFFERENT


which is not injured by slight movements of the caterpillar, nor

by consuming food decomposed rather than fresh caterpillar."

This illustrates how love of the marvellous may mislead even so

careful an observer as Fabre and so eminent a philosopher as


In the same chapter of Dr. Drever's book there are some

interesting examples of the mistakes made by instinct. I will

quote one as a sample:

"The larva of the Lomechusa beetle eats the young of the ants, in

whose nest it is reared. Nevertheless, the ants tend the

Lomechusa larvae with the same care they bestow on their own

young. Not only so, but they apparently discover that the methods

of feeding, which suit their own larvae, would prove fatal to the

guests, and accordingly they change their whole system of

nursing" (loc. cit., p. 106).

Semon ("Die Mneme," pp. 207-9) gives a good illustration of an

instinct growing wiser through experience. He relates how hunters

attract stags by imitating the sounds of other members of their

species, male or female, but find that the older a stag becomes

the more difficult it is to deceive him, and the more accurate

the imitation has to be. The literature of instinct is vast, and

illustrations might be multiplied indefinitely. The main points

as regards instinct, which need to be emphasized as against the

popular conceptions of it, are:

(1) That instinct requires no prevision of the biological end

which it serves;

(2) That instinct is only adapted to achieve this end in the

usual circumstances of the animal in question, and has no more

precision than is necessary for success AS A RULE;

(3) That processes initiated by instinct often come to be

performed better after experience;

(4) That instinct supplies the impulses to experimental movements

which are required for the process of learning;

(5) That instincts in their nascent stages are easily modifiable,

and capable of being attached to various sorts of objects.

All the above characteristics of instinct can be established by

purely external observation, except the fact that instinct does

not require prevision. This, though not strictly capable of being

PROVED by observation, is irresistibly suggested by the most

obvious phenomena. Who can believe, for example, that a new-born

baby is aware of the necessity of food for preserving life? Or

that insects, in laying eggs, are concerned for the preservation

of their species? The essence of instinct, one might say, is that

it provides a mechanism for acting without foresight in a manner

which is usually advantageous biologically. It is partly for this

reason that it is so important to understand the fundamental

position of instinct in prompting both animal and human



Desire is a subject upon which, if I am not mistaken, true views

can only be arrived at by an almost complete reversal of the

ordinary unreflecting opinion. It is natural to regard desire as

in its essence an attitude towards something which is imagined,

not actual; this something is called the END or OBJECT of the

desire, and is said to be the PURPOSE of any action resulting

from the desire. We think of the content of the desire as being

just like the content of a belief, while the attitude taken up

towards the content is different. According to this theory, when

we say: "I hope it will rain," or "I expect it will rain," we

express, in the first case, a desire, and in the second, a

belief, with an identical content, namely, the image of rain. It

would be easy to say that, just as belief is one kind of feeling

in relation to this content, so desire is another kind. According

to this view, what comes first in desire is something imagined,

with a specific feeling related to it, namely, that specific

feeling which we call "desiring" it. The discomfort associated

with unsatisfied desire, and the actions which aim at satisfying

desire, are, in this view, both of them effects of the desire. I

think it is fair to say that this is a view against which common

sense would not rebel; nevertheless, I believe it to be radically

mistaken. It cannot be refuted logically, but various facts can

be adduced which make it gradually less simple and plausible,

until at last it turns out to be easier to abandon it wholly and

look at the matter in a totally different way.

The first set of facts to be adduced against the common sense

view of desire are those studied by psycho-analysis. In all human

beings, but most markedly in those suffering from hysteria and

certain forms of insanity, we find what are called "unconscious"

desires, which are commonly regarded as showing self-deception.

Most psycho-analysts pay little attention to the analysis of

desire, being interested in discovering by observation what it is

that people desire, rather than in discovering what actually

constitutes desire. I think the strangeness of what they report

would be greatly diminished if it were expressed in the language

of a behaviourist theory of desire, rather than in the language

of every-day beliefs. The general description of the sort of

phenomena that bear on our present question is as follows: A

person states that his desires are so-and-so, and that it is

these desires that inspire his actions; but the outside observer

perceives that his actions are such as to realize quite different

ends from those which he avows, and that these different ends are

such as he might be expected to desire. Generally they are less

virtuous than his professed desires, and are therefore less

agreeable to profess than these are. It is accordingly supposed

that they really exist as desires for ends, but in a subconscious

part of the mind, which the patient refuses to admit into

consciousness for fear of having to think ill of himself. There

are no doubt many cases to which such a supposition is applicable

without obvious artificiality. But the deeper the Freudians delve

into the underground regions of instinct, the further they travel

from anything resembling conscious desire, and the less possible

it becomes to believe that only positive self-deception conceals

from us that we really wish for things which are abhorrent to our

explicit life.

In the cases in question we have a conflict between the outside

observer and the patient's consciousness. The whole tendency of

psycho-analysis is to trust the outside observer rather than the

testimony of introspection. I believe this tendency to be

entirely right, but to demand a re-statement of what constitutes

desire, exhibiting it as a causal law of our actions, not as

something actually existing in our minds.

But let us first get a clearer statement of the essential

characteristic of the phenomena.

A person, we find, states that he desires a certain end A, and

that he is acting with a view to achieving it. We observe,

however, that his actions are such as are likely to achieve a

quite different end B, and that B is the sort of end that often

seems to be aimed at by animals and savages, though civilized

people are supposed to have discarded it. We sometimes find also

a whole set of false beliefs, of such a kind as to persuade the

patient that his actions are really a means to A, when in fact

they are a means to B. For example, we have an impulse to inflict

pain upon those whom we hate; we therefore believe that they are

wicked, and that punishment will reform them. This belief enables

us to act upon the impulse to inflict pain, while believing that

we are acting upon the desire to lead sinners to repentance. It

is for this reason that the criminal law has been in all ages

more severe than it would have been if the impulse to ameliorate

the criminal had been what really inspired it. It seems simple to

explain such a state of affairs as due to "self-deception," but

this explanation is often mythical. Most people, in thinking

about punishment, have had no more need to hide their vindictive

impulses from themselves than they have had to hide the

exponential theorem. Our impulses are not patent to a casual

observation, but are only to be discovered by a scientific study

of our actions, in the course of which we must regard ourselves

as objectively as we should the motions of the planets or the

chemical reactions of a new element.

The study of animals reinforces this conclusion, and is in many

ways the best preparation for the analysis of desire. In animals

we are not troubled by the disturbing influence of ethical

considerations. In dealing with human beings, we are perpetually

distracted by being told that such-and-such a view is gloomy or

cynical or pessimistic: ages of human conceit have built up such

a vast myth as to our wisdom and virtue that any intrusion of the

mere scientific desire to know the facts is instantly resented by

those who cling to comfortable illusions. But no one cares

whether animals are virtuous or not, and no one is under the

delusion that they are rational. Moreover, we do not expect them

to be so "conscious," and are prepared to admit that their

instincts prompt useful actions without any prevision of the ends

which they achieve. For all these reasons, there is much in the

analysis of mind which is more easily discovered by the study of

animals than by the observation of human beings.

We all think that, by watching the behaviour of animals, we can

discover more or less what they desire. If this is the case--and

I fully agree that it is--desire must be capable of being

exhibited in actions, for it is only the actions of animals that

we can observe. They MAY have minds in which all sorts of things

take place, but we can know nothing about their minds except by

means of inferences from their actions; and the more such

inferences are examined, the more dubious they appear. It would

seem, therefore, that actions alone must be the test of the

desires of animals. From this it is an easy step to the

conclusion that an animal's desire is nothing but a

characteristic of a certain series of actions, namely, those

which would be commonly regarded as inspired by the desire in

question. And when it has been shown that this view affords a

satisfactory account of animal desires, it is not difficult to

see that the same explanation is applicable to the desires of

human beings.

We judge easily from the behaviour of an animal of a familiar

kind whether it is hungry or thirsty, or pleased or displeased,

or inquisitive or terrified. The verification of our judgment, so

far as verification is possible, must be derived from the

immediately succeeding actions of the animal. Most people would

say that they infer first something about the animal's state of

mind--whether it is hungry or thirsty and so on--and thence

derive their expectations as to its subsequent conduct. But this

detour through the animal's supposed mind is wholly unnecessary.

We can say simply: The animal's behaviour during the last minute

has had those characteristics which distinguish what is called

"hunger," and it is likely that its actions during the next

minute will be similar in this respect, unless it finds food, or

is interrupted by a stronger impulse, such as fear. An animal

which is hungry is restless, it goes to the places where food is

often to be found, it sniffs with its nose or peers with its eyes

or otherwise increases the sensitiveness of its sense-organs; as

soon as it is near enough to food for its sense-organs to be

affected, it goes to it with all speed and proceeds to eat; after

which, if the quantity of food has been sufficient, its whole

demeanour changes it may very likely lie down and go to sleep.

These things and others like them are observable phenomena

distinguishing a hungry animal from one which is not hungry. The

characteristic mark by which we recognize a series of actions

which display hunger is not the animal's mental state, which we

cannot observe, but something in its bodily behaviour; it is this

observable trait in the bodily behaviour that I am proposing to

call "hunger," not some possibly mythical and certainly

unknowable ingredient of the animal's mind.

Generalizing what occurs in the case of hunger, we may say that

what we call a desire in an animal is always displayed in a cycle

of actions having certain fairly well marked characteristics.

There is first a state of activity, consisting, with

qualifications to be mentioned presently, of movements likely to

have a certain result; these movements, unless interrupted,

continue until the result is achieved, after which there is

usually a period of comparative quiescence. A cycle of actions of

this sort has marks by which it is broadly distinguished from the

motions of dead matter. The most notable of these marks are--(1)

the appropriateness of the actions for the realization of a

certain result; (2) the continuance of action until that result

has been achieved. Neither of these can be pressed beyond a

point. Either may be (a) to some extent present in dead matter,

and (b) to a considerable extent absent in animals, while

vegetable are intermediate, and display only a much fainter form

of the behaviour which leads us to attribute desire to animals.

(a) One might say rivers "desire" the sea water, roughly

speaking, remains in restless motion until it reaches either the

sea or a place from which it cannot issue without going uphill,

and therefore we might say that this is what it wishes while it

is flowing. We do not say so, because we can account for the

behaviour of water by the laws of physics; and if we knew more

about animals, we might equally cease to attribute desires to

them, since we might find physical and chemical reactions

sufficient to account for their behaviour. (b) Many of the

movements of animals do not exhibit the characteristics of the

cycles which seem to embody desire. There are first of all the

movements which are "mechanical," such as slipping and falling,

where ordinary physical forces operate upon the animal's body

almost as if it were dead matter. An animal which falls over a

cliff may make a number of desperate struggles while it is in the

air, but its centre of gravity will move exactly as it would if

the animal were dead. In this case, if the animal is killed at

the end of the fall, we have, at first sight, just the

characteristics of a cycle of actions embodying desire, namely,

restless movement until the ground is reached, and then

quiescence. Nevertheless, we feel no temptation to say that the

animal desired what occurred, partly because of the obviously

mechanical nature of the whole occurrence, partly because, when

an animal survives a fall, it tends not to repeat the experience.

There may be other reasons also, but of them I do not wish to

speak yet. Besides mechanical movements, there are interrupted

movements, as when a bird, on its way to eat your best peas, is

frightened away by the boy whom you are employing for that

purpose. If interruptions are frequent and completion of cycles

rare, the characteristics by which cycles are observed may become

so blurred as to be almost unrecognizable. The result of these

various considerations is that the differences between animals

and dead matter, when we confine ourselves to external

unscientific observation of integral behaviour, are a matter of

degree and not very precise. It is for this reason that it has

always been possible for fanciful people to maintain that even

stocks and stones have some vague kind of soul. The evidence that

animals have souls is so very shaky that, if it is assumed to be

conclusive, one might just as well go a step further and extend

the argument by analogy to all matter. Nevertheless, in spite of

vagueness and doubtful cases, the existence of cycles in the

behaviour of animals is a broad characteristic by which they are

prima facie distinguished from ordinary matter; and I think it is

this characteristic which leads us to attribute desires to

animals, since it makes their behaviour resemble what we do when

(as we say) we are acting from desire.

I shall adopt the following definitions for describing the

behaviour of animals:

A "behaviour-cycle" is a series of voluntary or reflex movements

of an animal, tending to cause a certain result, and continuing

until that result is caused, unless they are interrupted by

death, accident, or some new behaviour-cycle. (Here "accident"

may be defined as the intervention of purely physical laws

causing mechanical movements.)

The "purpose" of a behaviour-cycle is the result which brings it

to an end, normally by a condition of temporary

quiescence-provided there is no interruption.

An animal is said to "desire" the purpose of a behaviour cycle

while the behaviour-cycle is in progress.

I believe these definitions to be adequate also to human purposes

and desires, but for the present I am only occupied with animals

and with what can be learnt by external observation. I am very

anxious that no ideas should be attached to the words "purpose"

and "desire" beyond those involved in the above definitions.

We have not so far considered what is the nature of the initial

stimulus to a behaviour-cycle. Yet it is here that the usual view

of desire seems on the strongest ground. The hungry animal goes

on making movements until it gets food; it seems natural,

therefore, to suppose that the idea of food is present throughout

the process, and that the thought of the end to be achieved sets

the whole process in motion. Such a view, however, is obviously

untenable in many cases, especially where instinct is concerned.

Take, for example, reproduction and the rearing of the young.

Birds mate, build a nest, lay eggs in it, sit on the eggs, feed

the young birds, and care for them until they are fully grown. It

is totally impossible to suppose that this series of actions,

which constitutes one behaviour-cycle, is inspired by any

prevision of the end, at any rate the first time it is

performed.* We must suppose that the stimulus to the performance

of each act is an impulsion from behind, not an attraction from

the future. The bird does what it does, at each stage, because it

has an impulse to that particular action, not because it

perceives that the whole cycle of actions will contribute to the

preservation of the species. The same considerations apply to

other instincts. A hungry animal feels restless, and is led by

instinctive impulses to perform the movements which give it

nourishment; but the act of seeking food is not sufficient

evidence from which to conclude that the animal has the thought

of food in its "mind."

* For evidence as to birds' nests, cf. Semon, "Die Mneme," pp.

209, 210.

Coming now to human beings, and to what we know about our own

actions, it seems clear that what, with us, sets a

behaviour-cycle in motion is some sensation of the sort which we

call disagreeable. Take the case of hunger: we have first an

uncomfortable feeling inside, producing a disinclination to sit

still, a sensitiveness to savoury smells, and an attraction

towards any food that there may be in our neighbourhood. At any

moment during this process we may become aware that we are

hungry, in the sense of saying to ourselves, "I am hungry"; but

we may have been acting with reference to food for some time

before this moment. While we are talking or reading, we may eat

in complete unconsciousness; but we perform the actions of eating

just as we should if we were conscious, and they cease when our

hunger is appeased. What we call "consciousness" seems to be a

mere spectator of the process; even when it issues orders, they

are usually, like those of a wise parent, just such as would have

been obeyed even if they had not been given. This view may seem

at first exaggerated, but the more our so-called volitions and

their causes are examined, the more it is forced upon us. The

part played by words in all this is complicated, and a potent

source of confusions; I shall return to it later. For the

present, I am still concerned with primitive desire, as it exists

in man, but in the form in which man shows his affinity to his

animal ancestors.

Conscious desire is made up partly of what is essential to

desire, partly of beliefs as to what we want. It is important to

be clear as to the part which does not consist of beliefs.

The primitive non-cognitive element in desire seems to be a push,

not a pull, an impulsion away from the actual, rather than an

attraction towards the ideal. Certain sensations and other mental

occurrences have a property which we call discomfort; these cause

such bodily movements as are likely to lead to their cessation.

When the discomfort ceases, or even when it appreciably

diminishes, we have sensations possessing a property which we

call PLEASURE. Pleasurable sensations either stimulate no action

at all, or at most stimulate such action as is likely to prolong

them. I shall return shortly to the consideration of what

discomfort and pleasure are in themselves; for the present, it is

their connection with action and desire that concerns us.

Abandoning momentarily the standpoint of behaviourism, we may

presume that hungry animals experience sensations involving

discomfort, and stimulating such movements as seem likely to

bring them to the food which is outside the cages. When they have

reached the food and eaten it, their discomfort ceases and their

sensations become pleasurable. It SEEMS, mistakenly, as if the

animals had had this situation in mind throughout, when in fact

they have been continually pushed by discomfort. And when an

animal is reflective, like some men, it comes to think that it

had the final situation in mind throughout; sometimes it comes to

know what situation will bring satisfaction, so that in fact the

discomfort does bring the thought of what will allay it.

Nevertheless the sensation involving discomfort remains the prime


This brings us to the question of the nature of discomfort and

pleasure. Since Kant it has been customary to recognize three

great divisions of mental phenomena, which are typified by

knowledge, desire and feeling, where "feeling" is used to mean

pleasure and discomfort. Of course, "knowledge" is too definite a

word: the states of mind concerned are grouped together as

"cognitive," and are to embrace not only beliefs, but

perceptions, doubts, and the understanding of concepts. "Desire,"

also, is narrower than what is intended: for example, WILL is to

be included in this category, and in fact every thing that

involves any kind of striving, or "conation" as it is technically

called. I do not myself believe that there is any value in this

threefold division of the contents of mind. I believe that

sensations (including images) supply all the "stuff" of the mind,

and that everything else can be analysed into groups of

sensations related in various ways, or characteristics of

sensations or of groups of sensations. As regards belief, I shall

give grounds for this view in later lectures. As regards desires,

I have given some grounds in this lecture. For the present, it is

pleasure and discomfort that concern us. There are broadly three

theories that might be held in regard to them. We may regard them

as separate existing items in those who experience them, or we

may regard them as intrinsic qualities of sensations and other

mental occurrences, or we may regard them as mere names for the

causal characteristics of the occurrences which are uncomfortable

or pleasant. The first of these theories, namely, that which

regards discomfort and pleasure as actual contents in those who

experience them, has, I think, nothing conclusive to be said in

its favour.* It is suggested chiefly by an ambiguity in the word

"pain," which has misled many people, including Berkeley, whom it

supplied with one of his arguments for subjective idealism. We

may use "pain" as the opposite of "pleasure," and "painful" as

the opposite of "pleasant," or we may use "pain" to mean a

certain sort of sensation, on a level with the sensations of heat

and cold and touch. The latter use of the word has prevailed in

psychological literature, and it is now no longer used as the

opposite of "pleasure." Dr. H. Head, in a recent publication, has

stated this distinction as follows:**

* Various arguments in its favour are advanced by A. Wohlgemuth,

"On the feelings and their neural correlate, with an examination

of the nature of pain," "British Journal of Psychology," viii, 4.

(1917). But as these arguments are largely a reductio ad absurdum

of other theories, among which that which I am advocating is not

included, I cannot regard them as establishing their contention.

** "Sensation and the Cerebral Cortex," "Brain," vol. xli, part

ii (September, 1918), p. 90. Cf. also Wohlgemuth, loc. cit. pp.

437, 450.

"It is necessary at the outset to distinguish clearly between

'discomfort' and 'pain.' Pain is a distinct sensory quality

equivalent to heat and cold, and its intensity can be roughly

graded according to the force expended in stimulation.

Discomfort, on the other hand, is that feeling-tone which is

directly opposed to pleasure. It may accompany sensations not in

themselves essentially painful; as for instance that produced by

tickling the sole of the foot. The reaction produced by repeated

pricking contains both these elements; for it evokes that sensory

quality known as pain, accompanied by a disagreeable

feeling-tone, which we have called discomfort. On the other hand,

excessive pressure, except when applied directly over some

nerve-trunk, tends to excite more discomfort than pain."

The confusion between discomfort and pain has made people regard

discomfort as a more substantial thing than it is, and this in

turn has reacted upon the view taken of pleasure, since

discomfort and pleasure are evidently on a level in this respect.

As soon as discomfort is clearly distinguished from the sensation

of pain, it becomes more natural to regard discomfort and

pleasure as properties of mental occurrences than to regard them

as separate mental occurrences on their own account. I shall

therefore dismiss the view that they are separate mental

occurrences, and regard them as properties of such experiences as

would be called respectively uncomfortable and pleasant.

It remains to be examined whether they are actual qualities of

such occurrences, or are merely differences as to causal

properties. I do not myself see any way of deciding this

question; either view seems equally capable of accounting for the

facts. If this is true, it is safer to avoid the assumption that

there are such intrinsic qualities of mental occurrences as are

in question, and to assume only the causal differences which are

undeniable. Without condemning the intrinsic theory, we can

define discomfort and pleasure as consisting in causal

properties, and say only what will hold on either of the two

theories. Following this course, we shall say:

"Discomfort" is a property of a sensation or other mental

occurrence, consisting in the fact that the occurrence in

question stimulates voluntary or reflex movements tending to

produce some more or less definite change involving the cessation

of the occurrence.

"Pleasure" is a property of a sensation or other mental

occurrence, consisting in the fact that the occurrence in

question either does not stimulate any voluntary or reflex

movement, or, if it does, stimulates only such as tend to prolong

the occurrence in question.*

* Cf. Thorndike, op. cit., p. 243.

"Conscious" desire, which we have now to consider, consists of

desire in the sense hitherto discussed, together with a true

belief as to its "purpose," i.e. as to the state of affairs that

will bring quiescence with cessation of the discomfort. If our

theory of desire is correct, a belief as to its purpose may very

well be erroneous, since only experience can show what causes a

discomfort to cease. When the experience needed is common and

simple, as in the case of hunger, a mistake is not very probable.

But in other cases--e.g. erotic desire in those who have had

little or no experience of its satisfaction--mistakes are to be

expected, and do in fact very often occur. The practice of

inhibiting impulses, which is to a great extent necessary to

civilized life, makes mistakes easier, by preventing experience

of the actions to which a desire would otherwise lead, and by

often causing the inhibited impulses themselves to be unnoticed

or quickly forgotten. The perfectly natural mistakes which thus

arise constitute a large proportion of what is, mistakenly in

part, called self-deception, and attributed by Freud to the


But there is a further point which needs emphasizing, namely,

that a belief that something is desired has often a tendency to

cause the very desire that is believed in. It is this fact that

makes the effect of "consciousness" on desire so complicated.

When we believe that we desire a certain state of affairs, that

often tends to cause a real desire for it. This is due partly to

the influence of words upon our emotions, in rhetoric for

example, and partly to the general fact that discomfort normally

belongs to the belief that we desire such-and-such a thing that

we do not possess. Thus what was originally a false opinion as to

the object of a desire acquires a certain truth: the false

opinion generates a secondary subsidiary desire, which

nevertheless becomes real. Let us take an illustration. Suppose

you have been jilted in a way which wounds your vanity. Your

natural impulsive desire will be of the sort expressed in Donne's


When by thy scorn, O Murderess, I am dead,

in which he explains how he will haunt the poor lady as a ghost,

and prevent her from enjoying a moment's peace. But two things

stand in the way of your expressing yourself so naturally: on the

one hand, your vanity, which will not acknowledge how hard you

are hit; on the other hand, your conviction that you are a

civilized and humane person, who could not possibly indulge so

crude a desire as revenge. You will therefore experience a

restlessness which will at first seem quite aimless, but will

finally resolve itself in a conscious desire to change your

profession, or go round the world, or conceal your identity and

live in Putney, like Arnold Bennett's hero. Although the prime

cause of this desire is a false judgment as to your previous

unconscious desire, yet the new conscious desire has its own

derivative genuineness, and may influence your actions to the

extent of sending you round the world. The initial mistake,

however, will have effects of two kinds. First, in uncontrolled

moments, under the influence of sleepiness or drink or delirium,

you will say things calculated to injure the faithless deceiver.

Secondly, you will find travel disappointing, and the East less

fascinating than you had hoped--unless, some day, you hear that

the wicked one has in turn been jilted. If this happens, you will

believe that you feel sincere sympathy, but you will suddenly be

much more delighted than before with the beauties of tropical

islands or the wonders of Chinese art. A secondary desire,

derived from a false judgment as to a primary desire, has its own

power of influencing action, and is therefore a real desire

according to our definition. But it has not the same power as a

primary desire of bringing thorough satisfaction when it is

realized; so long as the primary desire remains unsatisfied,

restlessness continues in spite of the secondary desire's

success. Hence arises a belief in the vanity of human wishes: the

vain wishes are those that are secondary, but mistaken beliefs

prevent us from realizing that they are secondary.

What may, with some propriety, be called self-deception arises

through the operation of desires for beliefs. We desire many

things which it is not in our power to achieve: that we should be

universally popular and admired, that our work should be the

wonder of the age, and that the universe should be so ordered as

to bring ultimate happiness to all, though not to our enemies

until they have repented and been purified by suffering. Such

desires are too large to be achieved through our own efforts. But

it is found that a considerable portion of the satisfaction which

these things would bring us if they were realized is to be

achieved by the much easier operation of believing that they are

or will be realized. This desire for beliefs, as opposed to

desire for the actual facts, is a particular case of secondary

desire, and, like all secondary desire its satisfaction does not

lead to a complete cessation of the initial discomfort.

Nevertheless, desire for beliefs, as opposed to desire for facts,

is exceedingly potent both individually and socially. According

to the form of belief desired, it is called vanity, optimism, or

religion. Those who have sufficient power usually imprison or put

to death any one who tries to shake their faith in their own

excellence or in that of the universe; it is for this reason that

seditious libel and blasphemy have always been, and still are,

criminal offences.

It is very largely through desires for beliefs that the primitive

nature of desire has become so hidden, and that the part played

by consciousness has been so confusing and so exaggerated.

We may now summarize our analysis of desire and feeling.

A mental occurrence of any kind--sensation, image, belief, or

emotion--may be a cause of a series of actions, continuing,

unless interrupted, until some more or less definite state of

affairs is realized. Such a series of actions we call a

"behaviour-cycle." The degree of definiteness may vary greatly:

hunger requires only food in general, whereas the sight of a

particular piece of food raises a desire which requires the

eating of that piece of food. The property of causing such a

cycle of occurrences is called "discomfort"; the property of the

mental occurrences in which the cycle ends is called " pleasure."

The actions constituting the cycle must not be purely mechanical,

i.e. they must be bodily movements in whose causation the special

properties of nervous tissue are involved. The cycle ends in a

condition of quiescence, or of such action as tends only to

preserve the status quo. The state of affairs in which this

condition of quiescence is achieved is called the "purpose" of

the cycle, and the initial mental occurrence involving discomfort

is called a "desire" for the state of affairs that brings

quiescence. A desire is called "conscious" when it is accompanied

by a true belief as to the state of affairs that will bring

quiescence; otherwise it is called "unconscious." All primitive

desire is unconscious, and in human beings beliefs as to the

purposes of desires are often mistaken. These mistaken beliefs

generate secondary desires, which cause various interesting

complications in the psychology of human desire, without

fundamentally altering the character which it shares with animal




In this lecture we shall be concerned with a very general

characteristic which broadly, though not absolutely,

distinguishes the behaviour of living organisms from that of dead

matter. The characteristic in question is this:

The response of an organism to a given stimulus is very often

dependent upon the past history of the organism, and not merely

upon the stimulus and the HITHERTO DISCOVERABLE present state of

the organism.

This characteristic is embodied in the saying "a burnt child

fears the fire." The burn may have left no visible traces, yet it

modifies the reaction of the child in the presence of fire. It is

customary to assume that, in such cases, the past operates by

modifying the structure of the brain, not directly. I have no

wish to suggest that this hypothesis is false; I wish only to

point out that it is a hypothesis. At the end of the present

lecture I shall examine the grounds in its favour. If we confine

ourselves to facts which have been actually observed, we must say

that past occurrences, in addition to the present stimulus and

the present ascertainable condition of the organism, enter into

the causation of the response.

The characteristic is not wholly confined to living organisms.

For example, magnetized steel looks just like steel which has not

been magnetized, but its behaviour is in some ways different. In

the case of dead matter, however, such phenomena are less

frequent and important than in the case of living organisms, and

it is far less difficult to invent satisfactory hypotheses as to

the microscopic changes of structure which mediate between the

past occurrence and the present changed response. In the case of

living organisms, practically everything that is distinctive both

of their physical and of their mental behaviour is bound up with

this persistent influence of the past. Further, speaking broadly,

the change in response is usually of a kind that is biologically

advantageous to the organism.

Following a suggestion derived from Semon ("Die Mneme," Leipzig,

1904; 2nd edition, 1908, English translation, Allen & Unwin,

1921; "Die mnemischen Empfindungen," Leipzig, l909), we will give

the name of "mnemic phenomena" to those responses of an organism

which, so far as hitherto observed facts are concerned, can only

be brought under causal laws by including past occurrences in the

history of the organism as part of the causes of the present

response. I do not mean merely--what would always be the

case--that past occurrences are part of a CHAIN of causes leading

to the present event. I mean that, in attempting to state the

PROXIMATE cause of the present event, some past event or events

must be included, unless we take refuge in hypothetical

modifications of brain structure.) For example: you smell

peat-smoke, and you recall some occasion when you smelt it

before. The cause of your recollection, so far as hitherto observ

able phenomena are concerned, consists both of the peat smoke

(present stimulus) and of the former occasion (past experience).

The same stimulus will not produce the same recollection in

another man who did not share your former experience, although

the former experience left no OBSERVABLE traces in the structure

of the brain. According to the maxim "same cause, same effect,"

we cannot therefore regard the peat-smoke alone as the cause of

your recollection, since it does not have the same effect in

other cases. The cause of your recollection must be both the

peat-smoke and the past occurrence. Accordingly your recollection

is an instance of what we are calling "mnemic phenomena."

Before going further, it will be well to give illustrations of

different classes of mnemic phenomena.

(a) ACQUIRED HABITS.--In Lecture II we saw how animals can learn

by experience how to get out of cages or mazes, or perform other

actions which are useful to them but not provided for by their

instincts alone. A cat which is put into a cage of which it has

had experience behaves differently from the way in which it

behaved at first. We can easily invent hypotheses, which are

quite likely to be true, as to connections in the brain caused by

past experience, and themselves causing the different response.

But the observable fact is that the stimulus of being in the cage

produces differing results with repetition, and that the

ascertainable cause of the cat's behaviour is not merely the cage

and its own ascertainable organization, but also its past history

in regard to the cage. From our present point of view, the matter

is independent of the question whether the cat's behaviour is due

to some mental fact called "knowledge," or displays a merely

bodily habit. Our habitual knowledge is not always in our minds,

but is called up by the appropriate stimuli. If we are asked

"What is the capital of France?" we answer "Paris," because of

past experience; the past experience is as essential as the

present question in the causation of our response. Thus all our

habitual knowledge consists of acquired habits, and comes under

the head of mnemic phenomena.

(b) IMAGES.--I shall have much to say about images in a later

lecture; for the present I am merely concerned with them in so

far as they are "copies" of past sensations. When you hear New

York spoken of, some image probably comes into your mind, either

of the place itself (if you have been there), or of some picture

of it (if you have not). The image is due to your past

experience, as well as to the present stimulus of the words "New

York." Similarly, the images you have in dreams are all dependent

upon your past experience, as well as upon the present stimulus

to dreaming. It is generally believed that all images, in their

simpler parts, are copies of sensations; if so, their mnemic

character is evident. This is important, not only on its own

account, but also because, as we shall see later, images play an

essential part in what is called "thinking."

(c) ASSOCIATION.--The broad fact of association, on the mental

side, is that when we experience something which we have

experienced before, it tends to call up the context of the former

experience. The smell of peat-smoke recalling a former scene is

an instance which we discussed a moment ago. This is obviously a

mnemic phenomenon. There is also a more purely physical

association, which is indistinguishable from physical habit. This

is the kind studied by Mr. Thorndike in animals, where a certain

stimulus is associated with a certain act. This is the sort which

is taught to soldiers in drilling, for example. In such a case

there need not be anything mental, but merely a habit of the

body. There is no essential distinction between association and

habit, and the observations which we made concerning habit as a

mnemic phenomenon are equally applicable to association.


object of a familiar kind, much of what appears subjectively to

be immediately given is really derived from past experience. When

we see an object, say a penny, we seem to be aware of its "real"

shape we have the impression of something circular, not of

something elliptical. In learning to draw, it is necessary to

acquire the art of representing things according to the

sensation, not according to the perception. And the visual

appearance is filled out with feeling of what the object would be

like to touch, and so on. This filling out and supplying of the

"real" shape and so on consists of the most usual correlates of

the sensational core in our perception. It may happen that, in

the particular case, the real correlates are unusual; for

example, if what we are seeing is a carpet made to look like

tiles. If so, the non-sensational part of our perception will be

illusory, i.e. it will supply qualities which the object in

question does not in fact have. But as a rule objects do have the

qualities added by perception, which is to be expected, since

experience of what is usual is the cause of the addition. If our

experience had been different, we should not fill out sensation

in the same way, except in so far as the filling out is

instinctive, not acquired. It would seem that, in man, all that

makes up space perception, including the correlation of sight and

touch and so on, is almost entirely acquired. In that case there

is a large mnemic element in all the common perceptions by means

of which we handle common objects. And, to take another kind of

instance, imagine what our astonishment would be if we were to

hear a cat bark or a dog mew. This emotion would be dependent

upon past experience, and would therefore be a mnemic phenomenon

according to the definition.

(e) MEMORY AS KNOWLEDGE.--The kind of memory of which I am now

speaking is definite knowledge of some past event in one's own

experience. From time to time we remember things that have

happened to us, because something in the present reminds us of

them. Exactly the same present fact would not call up the same

memory if our past experience had been different. Thus our

remembering is caused by--

(1) The present stimulus,

(2) The past occurrence.

It is therefore a mnemic phenomenon according to our definition.

A definition of "mnemic phenomena" which did not include memory

would, of course, be a bad one. The point of the definition is

not that it includes memory, but that it includes it as one of a

class of phenomena which embrace all that is characteristic in

the subject matter of psychology.

(f) EXPERIENCE.--The word "experience" is often used very

vaguely. James, as we saw, uses it to cover the whole primal

stuff of the world, but this usage seems objection able, since,

in a purely physical world, things would happen without there

being any experience. It is only mnemic phenomena that embody

experience. We may say that an animal "experiences" an occurrence

when this occurrence modifies the animal's subsequent behaviour,

i.e. when it is the mnemic portion of the cause of future

occurrences in the animal's life. The burnt child that fears the

fire has "experienced" the fire, whereas a stick that has been

thrown on and taken off again has not "experienced" anything,

since it offers no more resistance than before to being thrown

on. The essence of "experience" is the modification of behaviour

produced by what is experienced. We might, in fact, define one

chain of experience, or one biography, as a series of occurrences

linked by mnemic causation. I think it is this characteristic,

more than any other, that distinguishes sciences dealing with

living organisms from physics.

The best writer on mnemic phenomena known to me is Richard Semon,

the fundamental part of whose theory I shall endeavour to

summarize before going further:

When an organism, either animal or plant, is subjected to a

stimulus, producing in it some state of excitement, the removal

of the stimulus allows it to return to a condition of

equilibrium. But the new state of equilibrium is different from

the old, as may be seen by the changed capacity for reaction. The

state of equilibrium before the stimulus may be called the

"primary indifference-state"; that after the cessation of the

stimulus, the "secondary indifference-state." We define the

"engraphic effect" of a stimulus as the effect in making a

difference between the primary and secondary indifference-states,

and this difference itself we define as the "engram" due to the

stimulus. "Mnemic phenomena" are defined as those due to engrams;

in animals, they are specially associated with the nervous

system, but not exclusively, even in man.

When two stimuli occur together, one of them, occurring

afterwards, may call out the reaction for the other also. We call

this an "ekphoric influence," and stimuli having this character

are called "ekphoric stimuli." In such a case we call the engrams

of the two stimuli "associated." All simultaneously generated

engrams are associated; there is also association of successively

aroused engrams, though this is reducible to simultaneous

association. In fact, it is not an isolated stimulus that leaves

an engram, but the totality of the stimuli at any moment;

consequently any portion of this totality tends, if it recurs, to

arouse the whole reaction which was aroused before. Semon holds

that engrams can be inherited, and that an animal's innate habits

may be due to the experience of its ancestors; on this subject he

refers to Samuel Butler.

Semon formulates two "mnemic principles." The first, or "Law of

Engraphy," is as follows: "All simultaneous excitements in an

organism form a connected simultaneous excitement-complex, which

as such works engraphically, i.e. leaves behind a connected

engram-complex, which in so far forms a whole" ("Die mnemischen

Empfindungen," p. 146). The second mnemic principle, or "Law of

Ekphory," is as follows: "The partial return of the energetic

situation which formerly worked engraphically operates

ekphorically on a simultaneous engram-complex" (ib., p. 173).

These two laws together represent in part a hypothesis (the

engram), and in part an observable fact. The observable fact is

that, when a certain complex of stimuli has originally caused a

certain complex of reactions, the recurrence of part of the

stimuli tends to cause the recurrence of the whole of the


Semon's applications of his fundamental ideas in various

directions are interesting and ingenious. Some of them will

concern us later, but for the present it is the fundamental

character of mnemic phenomena that is in question.

Concerning the nature of an engram, Semon confesses that at

present it is impossible to say more than that it must consist in

some material alteration in the body of the organism ("Die

mnemischen Empfindungen," p. 376). It is, in fact, hypothetical,

invoked for theoretical uses, and not an outcome of direct

observation. No doubt physiology, especially the disturbances of

memory through lesions in the brain, affords grounds for this

hypothesis; nevertheless it does remain a hypothesis, the

validity of which will be discussed at the end of this lecture.

I am inclined to think that, in the present state of physiology,

the introduction of the engram does not serve to simplify the

account of mnemic phenomena. We can, I think, formulate the known

laws of such phenomena in terms, wholly, of observable facts, by

recognizing provisionally what we may call "mnemic causation." By

this I mean that kind of causation of which I spoke at the

beginning of this lecture, that kind, namely, in which the

proximate cause consists not merely of a present event, but of

this together with a past event. I do not wish to urge that this

form of causation is ultimate, but that, in the present state of

our knowledge, it affords a simplification, and enables us to

state laws of behaviour in less hypothetical terms than we should

otherwise have to employ.

The clearest instance of what I mean is recollection of a past

event. What we observe is that certain present stimuli lead us to

recollect certain occurrences, but that at times when we are not

recollecting them, there is nothing discoverable in our minds

that could be called memory of them. Memories, as mental facts,

arise from time to time, but do not, so far as we can see, exist

in any shape while they are "latent." In fact, when we say that

they are "latent," we mean merely that they will exist under

certain circumstances. If, then, there is to be some standing

difference between the person who can remember a certain fact and

the person who cannot, that standing difference must be, not in

anything mental, but in the brain. It is quite probable that

there is such a difference in the brain, but its nature is

unknown and it remains hypothetical. Everything that has, so far,

been made matter of observation as regards this question can be

put together in the statement: When a certain complex of

sensations has occurred to a man, the recurrence of part of the

complex tends to arouse the recollection of the whole. In like

manner, we can collect all mnemic phenomena in living organisms

under a single law, which contains what is hitherto verifiable in

Semon's two laws. This single law is:




This law would need to be supplemented by some account of the

influence of frequency, and so on; but it seems to contain the

essential characteristic of mnemic phenomena, without admixture

of anything hypothetical.

Whenever the effect resulting from a stimulus to an organism

differs according to the past history of the organism, without

our being able actually to detect any relevant difference in its

present structure, we will speak of "mnemic causation," provided

we can discover laws embodying the influence of the past. In

ordinary physical causation, as it appears to common sense, we

have approximate uniformities of sequence, such as "lightning is

followed by thunder," "drunkenness is followed by headache," and

so on. None of these sequences are theoretically invariable,

since something may intervene to disturb them. In order to obtain

invariable physical laws, we have to proceed to differential

equations, showing the direction of change at each moment, not

the integral change after a finite interval, however short. But

for the purposes of daily life many sequences are to all in tents

and purposes invariable. With the behaviour of human beings,

however, this is by no means the case. If you say to an

Englishman, "You have a smut on your nose," he will proceed to

remove it, but there will be no such effect if you say the same

thing to a Frenchman who knows no English. The effect of words

upon the hearer is a mnemic phenomena, since it depends upon the

past experience which gave him understanding of the words. If

there are to be purely psychological causal laws, taking no

account of the brain and the rest of the body, they will have to

be of the form, not "X now causes Y now," but--

"A, B, C, . . . in the past, together with X now, cause Y now."

For it cannot be successfully maintained that our understanding

of a word, for example, is an actual existent content of the mind

at times when we are not thinking of the word. It is merely what

may be called a "disposition," i.e. it is capable of being

aroused whenever we hear the word or happen to think of it. A

"disposition" is not something actual, but merely the mnemic

portion of a mnemic causal law.

In such a law as "A, B, C, . . . in the past, together with X

now, cause Y now," we will call A, B, C, . . . the mnemic cause,

X the occasion or stimulus, and Y the reaction. All cases in

which experience influences behaviour are instances of mnemic


Believers in psycho-physical parallelism hold that psychology can

theoretically be freed entirely from all dependence on physiology

or physics. That is to say, they believe that every psychical

event has a psychical cause and a physical concomitant. If there

is to be parallelism, it is easy to prove by mathematical logic

that the causation in physical and psychical matters must be of

the same sort, and it is impossible that mnemic causation should

exist in psychology but not in physics. But if psychology is to

be independent of physiology, and if physiology can be reduced to

physics, it would seem that mnemic causation is essential in

psychology. Otherwise we shall be compelled to believe that all

our knowledge, all our store of images and memories, all our

mental habits, are at all times existing in some latent mental

form, and are not merely aroused by the stimuli which lead to

their display. This is a very difficult hypothesis. It seems to

me that if, as a matter of method rather than metaphysics, we

desire to obtain as much independence for psychology as is

practically feasible, we shall do better to accept mnemic

causation in psychology protem, and therefore reject parallelism,

since there is no good ground for admitting mnemic causation in


It is perhaps worth while to observe that mnemic causation is

what led Bergson to deny that there is causation. at all in the

psychical sphere. He points out, very truly, that the same

stimulus, repeated, does not have the same consequences, and he

argues that this is contrary to the maxim, "same cause, same

effect." It is only necessary, however, to take account of past

occurrences and include them with the cause, in order to

re-establish the maxim, and the possibility of psychological

causal laws. The metaphysical conception of a cause lingers in

our manner of viewing causal laws: we want to be able to FEEL a

connection between cause and effect, and to be able to imagine

the cause as "operating." This makes us unwilling to regard

causal laws as MERELY observed uniformities of sequence; yet that

is all that science has to offer. To ask why such-and-such a kind

of sequence occurs is either to ask a meaningless question, or to

demand some more general kind of sequence which includes the one

in question. The widest empirical laws of sequence known at any

time can only be "explained" in the sense of being subsumed by

later discoveries under wider laws; but these wider laws, until

they in turn are subsumed, will remain brute facts, resting

solely upon observation, not upon some supposed inherent


There is therefore no a priori objection to a causal law in which

part of the cause has ceased to exist. To argue against such a

law on the ground that what is past cannot operate now, is to

introduce the old metaphysical notion of cause, for which science

can find no place. The only reason that could be validly alleged

against mnemic causation would be that, in fact, all the

phenomena can be explained without it. They are explained without

it by Semon's "engram," or by any theory which regards the

results of experience as embodied in modifications of the brain

and nerves. But they are not explained, unless with extreme

artificiality, by any theory which regards the latent effects of

experience as psychical rather than physical. Those who desire to

make psychology as far as possible independent of physiology

would do well, it seems to me, if they adopted mnemic causation.

For my part, however, I have no such desire, and I shall

therefore endeavour to state the grounds which occur to me in

favour of some such view as that of the "engram."

One of the first points to be urged is that mnemic phenomena are

just as much to be found in physiology as in psychology. They are

even to be found in plants, as Sir Francis Darwin pointed out

(cf. Semon, "Die Mneme," 2nd edition, p. 28 n.). Habit is a

characteristic of the body at least as much as of the mind. We

should, therefore, be compelled to allow the intrusion of mnemic

causation, if admitted at all, into non-psychological regions,

which ought, one feels, to be subject only to causation of the

ordinary physical sort. The fact is that a great deal of what, at

first sight, distinguishes psychology from physics is found, on

examination, to be common to psychology and physiology; this

whole question of the influence of experience is a case in point.

Now it is possible, of course, to take the view advocated by

Professor J. S. Haldane, who contends that physiology is not

theoretically reducible to physics and chemistry.* But the weight

of opinion among physiologists appears to be against him on this

point; and we ought certainly to require very strong evidence

before admitting any such breach of continuity as between living

and dead matter. The argument from the existence of mnemic

phenomena in physiology must therefore be allowed a certain

weight against the hypothesis that mnemic causation is ultimate.

* See his "The New Physiology and Other Addresses," Griffin,

1919, also the symposium, "Are Physical, Biological and

Psychological Categories Irreducible?" in "Life and Finite

Individuality," edited for the Aristotelian Society, with an

Introduction. By H. Wildon Carr, Williams & Norgate, 1918.

The argument from the connection of brain-lesions with loss of

memory is not so strong as it looks, though it has also, some

weight. What we know is that memory, and mnemic phenomena

generally, can be disturbed or destroyed by changes in the brain.

This certainly proves that the brain plays an essential part in

the causation of memory, but does not prove that a certain state

of the brain is, by itself, a sufficient condition for the

existence of memory. Yet it is this last that has to be proved.

The theory of the engram, or any similar theory, has to maintain

that, given a body and brain in a suitable state, a man will have

a certain memory, without the need of any further conditions.

What is known, however, is only that he will not have memories if

his body and brain are not in a suitable state. That is to say,

the appropriate state of body and brain is proved to be necessary

for memory, but not to be sufficient. So far, therefore, as our

definite knowledge goes, memory may require for its causation a

past occurrence as well as a certain present state of the brain.

In order to prove conclusively that mnemic phenomena arise

whenever certain physiological conditions are fulfilled, we ought

to be able actually to see differences between the brain of a man

who speaks English and that of a man who speaks French, between

the brain of a man who has seen New York and can recall it, and

that of a man who has never seen that city. It may be that the

time will come when this will be possible, but at present we are

very far removed from it. At present, there is, so far as I am

aware, no good evidence that every difference between the

knowledge possessed by A and that possessed by B is paralleled by

some difference in their brains. We may believe that this is the

case, but if we do, our belief is based upon analogies and

general scientific maxims, not upon any foundation of detailed

observation. I am myself inclined, as a working hypothesis, to

adopt the belief in question, and to hold that past experience

only affects present behaviour through modifications of

physiological structure. But the evidence seems not quite

conclusive, so that I do not think we ought to forget the other

hypothesis, or to reject entirely the possibility that mnemic

causation may be the ultimate explanation of mnemic phenomena. I

say this, not because I think it LIKELY that mnemic causation is

ultimate, but merely because I think it POSSIBLE, and because it

often turns out important to the progress of science to remember

hypotheses which have previously seemed improbable.


The traditional conception of cause and effect is one which

modern science shows to be fundamentally erroneous, and requiring

to be replaced by a quite different notion, that of LAWS OF

CHANGE. In the traditional conception, a particular event A

caused a particular event B, and by this it was implied that,

given any event B, some earlier event A could be discovered which

had a relation to it, such that--

(1) Whenever A occurred, it was followed by B;

(2) In this sequence, there was something "necessary," not a mere

de facto occurrence of A first and then B.

The second point is illustrated by the old discussion as to

whether it can be said that day causes night, on the ground that

day is always followed by night. The orthodox answer was that day

could not be called the cause of night, because it would not be

followed by night if the earth's rotation were to cease, or

rather to grow so slow that one complete rotation would take a

year. A cause, it was held, must be such that under no

conceivable circumstances could it fail to be followed by its


As a matter of fact, such sequences as were sought by believers

in the traditional form of causation have not so far been found

in nature. Everything in nature is apparently in a state of

continuous change,* so that what we call one "event" turns out to

be really a process. If this event is to cause another event, the

two will have to be contiguous in time; for if there is any

interval between them, something may happen during that interval

to prevent the expected effect. Cause and effect, therefore, will

have to be temporally contiguous processes. It is difficult to

believe, at any rate where physical laws are concerned, that the

earlier part of the process which is the cause can make any

difference to the effect, so long as the later part of the

process which is the cause remains unchanged. Suppose, for

example, that a man dies of arsenic poisoning, we say that his

taking arsenic was the cause of death. But clearly the process by

which he acquired the arsenic is irrelevant: everything that

happened before he swallowed it may be ignored, since it cannot

alter the effect except in so far as it alters his condition at

the moment of taking the dose. But we may go further: swallowing

arsenic is not really the proximate cause of death, since a man

might be shot through the head immediately after taking the dose,

and then it would not be of arsenic that he would die. The

arsenic produces certain physiological changes, which take a

finite time before they end in death. The earlier parts of these

changes can be ruled out in the same way as we can rule out the

process by which the arsenic was acquired. Proceeding in this

way, we can shorten the process which we are calling the cause

more and more. Similarly we shall have to shorten the effect. It

may happen that immediately after the man's death his body is

blown to pieces by a bomb. We cannot say what will happen after

the man's death, through merely knowing that he has died as the

result of arsenic poisoning. Thus, if we are to take the cause as

one event and the effect as another, both must be shortened

indefinitely. The result is that we merely have, as the

embodiment of our causal law, a certain direction of change at

each moment. Hence we are brought to differential equations as

embodying causal laws. A physical law does not say "A will be

followed by B," but tells us what acceleration a particle will

have under given circumstances, i.e. it tells us how the

particle's motion is changing at each moment, not where the

particle will be at some future moment.

* The theory of quanta suggests that the continuity is only

apparent. If so, we shall be able theoretically to reach events

which are not processes. But in what is directly observable there

is still apparent continuity, which justifies the above remarks

for the prevent.

Laws embodied in differential equations may possibly be exact,

but cannot be known to be so. All that we can know empirically is

approximate and liable to exceptions; the exact laws that are

assumed in physics are known to be somewhere near the truth, but

are not known to be true just as they stand. The laws that we

actually know empirically have the form of the traditional causal

laws, except that they are not to be regarded as universal or

necessary. "Taking arsenic is followed by death" is a good

empirical generalization; it may have exceptions, but they will

be rare. As against the professedly exact laws of physics, such

empirical generalizations have the advantage that they deal with

observable phenomena. We cannot observe infinitesimals, whether

in time or space; we do not even know whether time and space are

infinitely divisible. Therefore rough empirical generalizations

have a definite place in science, in spite of not being exact of

universal. They are the data for more exact laws, and the grounds

for believing that they are USUALLY true are stronger than the

grounds for believing that the more exact laws are ALWAYS true.

Science starts, therefore, from generalizations of the form, "A

is usually followed by B." This is the nearest approach that can

be made to a causal law of the traditional sort. It may happen in

any particular instance that A is ALWAYS followed by B, but we

cannot know this, since we cannot foresee all the perfectly

possible circumstances that might make the sequence fail, or know

that none of them will actually occur. If, however, we know of a

very large number of cases in which A is followed by B, and few

or none in which the sequence fails, we shall in PRACTICE be

justified in saying "A causes B," provided we do not attach to

the notion of cause any of the metaphysical superstitions that

have gathered about the word.

There is another point, besides lack of universality and

necessity, which it is important to realize as regards causes in

the above sense, and that is the lack of uniqueness. It is

generally assumed that, given any event, there is some one

phenomenon which is THE cause of the event in question. This

seems to be a mere mistake. Cause, in the only sense in which it

can be practically applied, means "nearly invariable antecedent."

We cannot in practice obtain an antecedent which is QUITE

invariable, for this would require us to take account of the

whole universe, since something not taken account of may prevent

the expected effect. We cannot distinguish, among nearly

invariable antecedents, one as THE cause, and the others as

merely its concomitants: the attempt to do this depends upon a

notion of cause which is derived from will, and will (as we shall

see later) is not at all the sort of thing that it is generally

supposed to be, nor is there any reason to think that in the

physical world there is anything even remotely analogous to what

will is supposed to be. If we could find one antecedent, and only

one, that was QUITE invariable, we could call that one THE cause

without introducing any notion derived from mistaken ideas about

will. But in fact we cannot find any antecedent that we know to

be quite invariable, and we can find many that are nearly so. For

example, men leave a factory for dinner when the hooter sounds at

twelve o'clock. You may say the hooter is THE cause of their

leaving. But innumerable other hooters in other factories, which

also always sound at twelve o'clock, have just as good a right to

be called the cause. Thus every event has many nearly invariable

antecedents, and therefore many antecedents which may be called

its cause.

The laws of traditional physics, in the form in which they deal

with movements of matter or electricity, have an apparent

simplicity which somewhat conceals the empirical character of

what they assert. A piece of matter, as it is known empirically,

is not a single existing thing, but a system of existing things.

When several people simultaneously see the same table, they all

see something different; therefore "the" table, which they are

supposed all to see, must be either a hypothesis or a

construction. "The" table is to be neutral as between different

observers: it does not favour the aspect seen by one man at the

expense of that seen by another. It was natural, though to my

mind mistaken, to regard the "real" table as the common cause of

all the appearances which the table presents (as we say) to

different observers. But why should we suppose that there is some

one common cause of all these appearances? As we have just seen,

the notion of "cause" is not so reliable as to allow us to infer

the existence of something that, by its very nature, can never be


Instead of looking for an impartial source, we can secure

neutrality by the equal representation of all parties. Instead of

supposing that there is some unknown cause, the "real" table,

behind the different sensations of those who are said to be

looking at the table, we may take the whole set of these

sensations (together possibly with certain other particulars) as

actually BEING the table. That is to say, the table which is

neutral as between different observers (actual and possible) is

the set of all those particulars which would naturally be called

"aspects" of the table from different points of view. (This is a

first approximation, modified later.)

It may be said: If there is no single existent which is the

source of all these "aspects," how are they collected together?

The answer is simple: Just as they would be if there were such a

single existent. The supposed "real" table underlying its

appearances is, in any case, not itself perceived, but inferred,

and the question whether such-and-such a particular is an

"aspect" of this table is only to be settled by the connection of

the particular in question with the one or more particulars by

which the table is defined. That is to say, even if we assume a

"real" table, the particulars which are its aspects have to be

collected together by their relations to each other, not to it,

since it is merely inferred from them. We have only, therefore,

to notice how they are collected together, and we can then keep

the collection without assuming any "real" table as distinct from

the collection. When different people see what they call the same

table, they see things which are not exactly the same, owing to

difference of point of view, but which are sufficiently alike to

be described in the same words, so long as no great accuracy or

minuteness is sought. These closely similar particulars are

collected together by their similarity primarily and, more

correctly, by the fact that they are related to each other

approximately according to the laws of perspective and of

reflection and diffraction of light. I suggest, as a first

approximation, that these particulars, together with such

correlated others as are unperceived, jointly ARE the table; and

that a similar definition applies to all physical objects.*

*See "Our Knowledge of the External World" (Allen & Unwin),

chaps. iii and iv.

In order to eliminate the reference to our perceptions, which

introduces an irrelevant psychological suggestion, I will take a

different illustration, namely, stellar photography. A

photographic plate exposed on a clear night reproduces the

appearance of the portion of the sky concerned, with more or

fewer stars according to the power of the telescope that is being

used. Each separate star which is photographed produces its

separate effect on the plate, just as it would upon ourselves if

we were looking at the sky. If we assume, as science normally

does, the continuity of physical processes, we are forced to

conclude that, at the place where the plate is, and at all places

between it and a star which it photographs, SOMETHING is

happening which is specially connected with that star. In the

days when the aether was less in doubt, we should have said that

what was happening was a certain kind of transverse vibration in

the aether. But it is not necessary or desirable to be so

explicit: all that we need say is that SOMETHING happens which is

specially connected with the star in question. It must be

something specially connected with that star, since that star

produces its own special effect upon the plate. Whatever it is

must be the end of a process which starts from the star and

radiates outwards, partly on general grounds of continuity,

partly to account for the fact that light is transmitted with a

certain definite velocity. We thus arrive at the conclusion that,

if a certain star is visible at a certain place, or could be

photographed by a sufficiently sensitive plate at that place,

something is happening there which is specially connected with

that star. Therefore in every place at all times a vast multitude

of things must be happening, namely, at least one for every

physical object which can be seen or photographed from that

place. We can classify such happenings on either of two


(1) We can collect together all the happenings in one place, as

is done by photography so far as light is concerned;

(2) We can collect together all the happenings, in different

places, which are connected in the way that common sense regards

as being due to their emanating from one object.

Thus, to return to the stars, we can collect together either--

(1) All the appearances of different stars in a given place, or,

(2) All the appearances of a given star in different places.

But when I speak of "appearances," I do so only for brevity: I do

not mean anything that must "appear" to somebody, but only that

happening, whatever it may be, which is connected, at the place

in question, with a given physical object--according to the old

orthodox theory, it would be a transverse vibration in the

aether. Like the different appearances of the table to a number

of simultaneous observers, the different particulars that belong

to one physical object are to be collected together by continuity

and inherent laws of correlation, not by their supposed causal

connection with an unknown assumed existent called a piece of

matter, which would be a mere unnecessary metaphysical thing in

itself. A piece of matter, according to the definition that I

propose, is, as a first approximation,* the collection of all

those correlated particulars which would normally be regarded as

its appearances or effects in different places. Some further

elaborations are desirable, but we can ignore them for the

present. I shall return to them at the end of this lecture.

*The exact definition of a piece of matter as a construction will

be given later.

According to the view that I am suggesting, a physical object or

piece of matter is the collection of all those correlated

particulars which would be regarded by common sense as its

effects or appearances in different places. On the other hand,

all the happenings in a given place represent what common sense

would regard as the appearances of a number of different objects

as viewed from that place. All the happenings in one place may be

regarded as the view of the world from that place. I shall call

the view of the world from a given place a "perspective." A

photograph represents a perspective. On the other hand, if

photographs of the stars were taken in all points throughout

space, and in all such photographs a certain star, say Sirius,

were picked out whenever it appeared, all the different

appearances of Sirius, taken together, would represent Sirius.

For the understanding of the difference between psychology and

physics it is vital to understand these two ways of classifying

particulars, namely:

(1) According to the place where they occur;

(2) According to the system of correlated particulars in

different places to which they belong, such system being defined

as a physical object.

Given a system of particulars which is a physical object, I shall

define that one of the system which is in a given place (if any)

as the "appearance of that object in that place."

When the appearance of an object in a given place changes, it is

found that one or other of two things occurs. The two

possibilities may be illustrated by an example. You are in a room

with a man, whom you see: you may cease to see him either by

shutting your eyes or by his going out of the room. In the first

case, his appearance to other people remains unchanged; in the

second, his appearance changes from all places. In the first

case, you say that it is not he who has changed, but your eyes;

in the second, you say that he has changed. Generalizing, we


(1) Cases in which only certain appearances of the object change,

while others, and especially appearances from places very near to

the object, do not change;

(2) Cases where all, or almost all, the appearances of the object

undergo a connected change.

In the first case, the change is attributed to the medium between

the object and the place; in the second, it is attributed to the

object itself.*

* The application of this distinction to motion raises

complications due to relativity, but we may ignore these for our

present purposes.

It is the frequency of the latter kind of change, and the

comparatively simple nature of the laws governing the

simultaneous alterations of appearances in such cases, that have

made it possible to treat a physical object as one thing, and to

overlook the fact that it is a system of particulars. When a

number of people at a theatre watch an actor, the changes in

their several perspectives are so similar and so closely

correlated that all are popularly regarded as identical with each

other and with the changes of the actor himself. So long as all

the changes in the appearances of a body are thus correlated

there is no pressing prima facie need to break up the system of

appearances, or to realize that the body in question is not

really one thing but a set of correlated particulars. It is

especially and primarily such changes that physics deals with,

i.e. it deals primarily with processes in which the unity of a

physical object need not be broken up because all its appearances

change simultaneously according to the same law--or, if not all,

at any rate all from places sufficiently near to the object, with

in creasing accuracy as we approach the object.

The changes in appearances of an object which are due to changes

in the intervening medium will not affect, or will affect only

very slightly, the appearances from places close to the object.

If the appearances from sufficiently neighbouring places are

either wholly un changed, or changed to a diminishing extent

which has zero for its limit, it is usually found that the

changes can be accounted for by changes in objects which are

between the object in question and the places from which its

appearance has changed appreciably. Thus physics is able to

reduce the laws of most changes with which it deals to changes in

physical objects, and to state most of its fundamental laws in

terms of matter. It is only in those cases in which the unity of

the system of appearances constituting a piece of matter has to

be broken up, that the statement of what is happening cannot be

made exclusively in terms of matter. The whole of psychology, we

shall find, is included among such cases; hence their importance

for our purposes.

We can now begin to understand one of the fundamental differences

between physics and psychology. Physics treats as a unit the

whole system of appearances of a piece of matter, whereas

psychology is interested in certain of these appearances

themselves. Confining ourselves for the moment to the psychology

of perceptions, we observe that perceptions are certain of the

appearances of physical objects. From the point of view that we

have been hitherto adopting, we might define them as the

appearances of objects at places from which sense-organs and the

suitable parts of the nervous system form part of the intervening

medium. Just as a photographic plate receives a different

impression of a cluster of stars when a telescope is part of the

intervening medium, so a brain receives a different impression

when an eye and an optic nerve are part of the intervening

medium. An impression due to this sort of intervening medium is

called a perception, and is interesting to psychology on its own

account, not merely as one of the set of correlated particulars

which is the physical object of which (as we say) we are having a


We spoke earlier of two ways of classifying particulars. One way

collects together the appearances commonly regarded as a given

object from different places; this is, broadly speaking, the way

of physics, leading to the construction of physical objects as

sets of such appearances. The other way collects together the

appearances of different objects from a given place, the result

being what we call a perspective. In the particular case where

the place concerned is a human brain, the perspective belonging

to the place consists of all the perceptions of a certain man at

a given time. Thus classification by perspectives is relevant to

psychology, and is essential in defining what we mean by one


I do not wish to suggest that the way in which I have been

defining perceptions is the only possible way, or even the best

way. It is the way that arose naturally out of our present topic.

But when we approach psychology from a more introspective

standpoint, we have to distinguish sensations and perceptions, if

possible, from other mental occurrences, if any. We have also to

consider the psychological effects of sensations, as opposed to

their physical causes and correlates. These problems are quite

distinct from those with which we have been concerned in the

present lecture, and I shall not deal with them until a later


It is clear that psychology is concerned essentially with actual

particulars, not merely with systems of particulars. In this it

differs from physics, which, broadly speaking, is concerned with

the cases in which all the particulars which make up one physical

object can be treated as a single causal unit, or rather the

particulars which are sufficiently near to the object of which

they are appearances can be so treated. The laws which physics

seeks can, broadly speaking, be stated by treating such systems

of particulars as causal units. The laws which psychology seeks

cannot be so stated, since the particulars themselves are what

interests the psychologist. This is one of the fundamental

differences between physics and psychology; and to make it clear

has been the main purpose of this lecture.

I will conclude with an attempt to give a more precise definition

of a piece of matter. The appearances of a piece of matter from

different places change partly according to intrinsic laws (the

laws of perspective, in the case of visual shape), partly

according to the nature of the intervening medium--fog, blue

spectacles, telescopes, microscopes, sense-organs, etc. As we

approach nearer to the object, the effect of the intervening

medium grows less. In a generalized sense, all the intrinsic laws

of change of appearance may be called "laws of perspective."

Given any appearance of an object, we can construct

hypothetically a certain system of appearances to which the

appearance in question would belong if the laws of perspective

alone were concerned. If we construct this hypothetical system

for each appearance of the object in turn, the system

corresponding to a given appearance x will be independent of any

distortion due to the medium beyond x, and will only embody such

distortion as is due to the medium between x and the object.

Thus, as the appearance by which our hypothetical system is

defined is moved nearer and nearer to the object, the

hypothetical system of appearances defined by its means embodies

less and less of the effect of the medium. The different sets of

appearances resulting from moving x nearer and nearer to the

object will approach to a limiting set, and this limiting set

will be that system of appearances which the object would present

if the laws of perspective alone were operative and the medium

exercised no distorting effect. This limiting set of appearances

may be defined, for purposes of physics, as the piece of matter



One of the main purposes of these lectures is to give grounds for

the belief that the distinction between mind and matter is not so

fundamental as is commonly supposed. In the preceding lecture I

dealt in outline with the physical side of this problem. I

attempted to show that what we call a material object is not

itself a substance, but is a system of particulars analogous in

their nature to sensations, and in fact often including actual

sensations among their number. In this way the stuff of which

physical objects are composed is brought into relation with the

stuff of which part, at least, of our mental life is composed.

There is, however, a converse task which is equally necessary for

our thesis, and that is, to show that the stuff of our mental

life is devoid of many qualities which it is commonly supposed to

have, and is not possessed of any attributes which make it

incapable of forming part of the world of matter. In the present

lecture I shall begin the arguments for this view.

Corresponding to the supposed duality of matter and mind, there

are, in orthodox psychology, two ways of knowing what exists. One

of these, the way of sensation and external perception, is

supposed to furnish data for our knowledge of matter, the other,

called "introspection," is supposed to furnish data for knowledge

of our mental processes. To common sense, this distinction seems

clear and easy. When you see a friend coming along the street,

you acquire knowledge of an external, physical fact; when you

realize that you are glad to meet him, you acquire knowledge of a

mental fact. Your dreams and memories and thoughts, of which you

are often conscious, are mental facts, and the process by which

you become aware of them SEEMS to be different from sensation.

Kant calls it the "inner sense"; sometimes it is spoken of as

"consciousness of self"; but its commonest name in modern English

psychology is "introspection." It is this supposed method of

acquiring knowledge of our mental processes that I wish to

analyse and examine in this lecture.

I will state at the outset the view which I shall aim at

establishing. I believe that the stuff of our mental life, as

opposed to its relations and structure, consists wholly of

sensations and images. Sensations are connected with matter in

the way that I tried to explain in Lecture V, i.e. each is a

member of a system which is a certain physical object. Images,

though they USUALLY have certain characteristics, especially lack

of vividness, that distinguish them from sensations, are not

INVARIABLY so distinguished, and cannot therefore be defined by

these characteristics. Images, as opposed to sensations, can only

be defined by their different causation: they are caused by

association with a sensation, not by a stimulus external to the

nervous system--or perhaps one should say external to the brain,

where the higher animals are concerned. The occurrence of a

sensation or image does not in itself constitute knowledge but

any sensation or image may come to be known if the conditions are

suitable. When a sensation--like the hearing of a clap of

thunder--is normally correlated with closely similar sensations

in our neighbours, we regard it as giving knowledge of the

external world, since we regard the whole set of similar

sensations as due to a common external cause. But images and

bodily sensations are not so correlated. Bodily sensations can be

brought into a correlation by physiology, and thus take their

place ultimately among sources of knowledge of the physical

world. But images cannot be made to fit in with the simultaneous

sensations and images of others. Apart from their hypothetical

causes in the brain, they have a causal connection with physical

objects, through the fact that they are copies of past

sensations; but the physical objects with which they are thus

connected are in the past, not in the present. These images

remain private in a sense in which sensations are not. A

sensation SEEMS to give us knowledge of a present physical

object, while an image does not, except when it amounts to a

hallucination, and in this case the seeming is deceptive. Thus

the whole context of the two occurrences is different. But in

themselves they do not differ profoundly, and there is no reason

to invoke two different ways of knowing for the one and for the

other. Consequently introspection as a separate kind of knowledge


The criticism of introspection has been in the main the work of

American psychologists. I will begin by summarizing an article

which seems to me to afford a good specimen of their arguments,

namely, "The Case against Introspection," by Knight Dunlap

("Psychological Review," vol xix, No. 5, pp. 404-413, September,

1912). After a few historical quotations, he comes to two modern

defenders of introspection, Stout and James. He quotes from Stout

such statements as the following: "Psychical states as such

become objects only when we attend to them in an introspective

way. Otherwise they are not themselves objects, but only

constituents of the process by which objects are recognized"

("Manual," 2nd edition, p. 134. The word "recognized" in Dunlap's

quotation should be "cognized.") "The object itself can never be

identified with the present modification of the individual's

consciousness by which it is cognized" (ib. p. 60). This is to be

true even when we are thinking about modifications of our own

consciousness; such modifications are to be always at least

partially distinct from the conscious experience in which we

think of them.

At this point I wish to interrupt the account of Knight Dunlap's

article in order to make some observations on my own account with

reference to the above quotations from Stout. In the first place,

the conception of "psychical states" seems to me one which

demands analysis of a somewhat destructive character. This

analysis I shall give in later lectures as regards cognition; I

have already given it as regards desire. In the second place, the

conception of "objects" depends upon a certain view as to

cognition which I believe to be wholly mistaken, namely, the view

which I discussed in my first lecture in connection with

Brentano. In this view a single cognitive occurrence contains

both content and object, the content being essentially mental,

while the object is physical except in introspection and abstract

thought. I have already criticized this view, and will not dwell

upon it now, beyond saying that "the process by which objects are

cognized" appears to be a very slippery phrase. When we "see a

table," as common sense would say, the table as a physical object

is not the "object" (in the psychological sense) of our

perception. Our perception is made up of sensations, images and

beliefs, but the supposed "object" is something inferential,

externally related, not logically bound up with what is occurring

in us. This question of the nature of the object also affects the

view we take of self-consciousness. Obviously, a "conscious

experience" is different from a physical object; therefore it is

natural to assume that a thought or perception whose object is a

conscious experience must be different from a thought or

perception whose object is a physical object. But if the relation

to the object is inferential and external, as I maintain, the

difference between two thoughts may bear very little relation to

the difference between their objects. And to speak of "the

present modification of the individual's consciousness by which

an object is cognized" is to suggest that the cognition of

objects is a far more direct process, far more intimately bound

up with the objects, than I believe it to be. All these points

will be amplified when we come to the analysis of knowledge, but

it is necessary briefly to state them now in order to suggest the

atmosphere in which our analysis of "introspection" is to be

carried on.

Another point in which Stout's remarks seem to me to suggest what

I regard as mistakes is his use of "consciousness." There is a

view which is prevalent among psychologists, to the effect that

one can speak of "a conscious experience" in a curious dual

sense, meaning, on the one hand, an experience which is conscious

of something, and, on the other hand, an experience which has

some intrinsic nature characteristic of what is called

"consciousness." That is to say, a "conscious experience" is

characterized on the one hand by relation to its object and on

the other hand by being composed of a certain peculiar stuff, the

stuff of "consciousness." And in many authors there is yet a

third confusion: a "conscious experience," in this third sense,

is an experience of which we are conscious. All these, it seems

to me, need to be clearly separated. To say that one occurrence

is "conscious" of another is, to my mind, to assert an external

and rather remote relation between them. I might illustrate it by

the relation of uncle and nephew a man becomes an uncle through

no effort of his own, merely through an occurrence elsewhere.

Similarly, when you are said to be "conscious" of a table, the

question whether this is really the case cannot be decided by

examining only your state of mind: it is necessary also to

ascertain whether your sensation is having those correlates which

past experience causes you to assume, or whether the table

happens, in this case, to be a mirage. And, as I explained in my

first lecture, I do not believe that there is any "stuff" of

consciousness, so that there is no intrinsic character by which a

"conscious" experience could be distinguished from any other.

After these preliminaries, we can return to Knight Dunlap's

article. His criticism of Stout turns on the difficulty of giving

any empirical meaning to such notions as the "mind" or the

"subject"; he quotes from Stout the sentence: "The most important

drawback is that the mind, in watching its own workings, must

necessarily have its attention divided between two objects," and

he concludes: "Without question, Stout is bringing in here

illicitly the concept of a single observer, and his introspection

does not provide for the observation of this observer; for the

process observed and the observer are distinct" (p. 407). The

objections to any theory which brings in the single observer were

considered in Lecture I, and were acknowledged to be cogent. In

so far, therefore, as Stout's theory of introspection rests upon

this assumption, we are compelled to reject it. But it is

perfectly possible to believe in introspection without supposing

that there is a single observer.

William James's theory of introspection, which Dunlap next

examines, does not assume a single observer. It changed after the

publication of his "Psychology," in consequence of his abandoning

the dualism of thought and things. Dunlap summarizes his theory

as follows:

"The essential points in James's scheme of consciousness are

SUBJECT, OBJECT,and a KNOWING of the object by the subject. The

difference between James's scheme and other schemes involving the

same terms is that James considers subject and object to be the

same thing, but at different times In order to satisfy this

requirement James supposes a realm of existence which he at first

called 'states of consciousness' or 'thoughts,' and later, 'pure

experience,' the latter term including both the 'thoughts' and

the 'knowing.' This scheme, with all its magnificent

artificiality, James held on to until the end, simply dropping

the term consciousness and the dualism between the thought and an

external reality"(p. 409).

He adds: "All that James's system really amounts to is the

acknowledgment that a succession of things are known, and that

they are known by something. This is all any one can claim,

except for the fact that the things are known together, and that

the knower for the different items is one and the same" (ib.).

In this statement, to my mind, Dunlap concedes far more than

James did in his later theory. I see no reason to suppose that

"the knower for different items is one and the same," and I am

convinced that this proposition could not possibly be ascertained

except by introspection of the sort that Dunlap rejects. The

first of these points must wait until we come to the analysis of

belief: the second must be considered now. Dunlap's view is that

there is a dualism of subject and object, but that the subject

can never become object, and therefore there is no awareness of

an awareness. He says in discussing the view that introspection

reveals the occurrence of knowledge: "There can be no denial of

the existence of the thing (knowing) which is alleged to be known

or observed in this sort of 'introspection.' The allegation that

the knowing is observed is that which may be denied. Knowing

there certainly is; known, the knowing certainly is not"(p. 410).

And again: "I am never aware of an awareness" (ib.). And on the

next page: "It may sound paradoxical to say that one cannot

observe the process (or relation) of observation, and yet may be

certain that there is such a process: but there is really no

inconsistency in the saying. How do I know that there is

awareness? By being aware of something. There is no meaning in

the term 'awareness' which is not expressed in the statement 'I

am aware of a colour (or what-not).' "

But the paradox cannot be so lightly disposed of. The statement

"I am aware of a colour" is assumed by Knight Dunlap to be known

to be true, but he does not explain how it comes to be known. The

argument against him is not conclusive, since he may be able to

show some valid way of inferring our awareness. But he does not

suggest any such way. There is nothing odd in the hypothesis of

beings which are aware of objects, but not of their own

awareness; it is, indeed, highly probable that young children and

the higher animals are such beings. But such beings cannot make

the statement "I am aware of a colour," which WE can make. We

have, therefore, some knowledge which they lack. It is necessary

to Knight Dunlap's position to maintain that this additional

knowledge is purely inferential, but he makes no attempt to show

how the inference is possible. It may, of course, be possible,

but I cannot see how. To my mind the fact (which he admits) that

we know there is awareness, is ALL BUT decisive against his

theory, and in favour of the view that we can be aware of an


Dunlap asserts (to return to James) that the real ground for

James's original belief in introspection was his belief in two

sorts of objects, namely, thoughts and things. He suggests that

it was a mere inconsistency on James's part to adhere to

introspection after abandoning the dualism of thoughts and

things. I do not wholly agree with this view, but it is difficult

to disentangle the difference as to introspection from the

difference as to the nature of knowing. Dunlap suggests (p. 411)

that what is called introspection really consists of awareness of

"images," visceral sensations, and so on. This view, in essence,

seems to me sound. But then I hold that knowing itself consists

of such constituents suitably related, and that in being aware of

them we are sometimes being aware of instances of knowing. For

this reason, much as I agree with his view as to what are the

objects of which there is awareness, I cannot wholly agree with

his conclusion as to the impossibility of introspection.

The behaviourists have challenged introspection even more

vigorously than Knight Dunlap, and have gone so far as to deny

the existence of images. But I think that they have confused

various things which are very commonly confused, and that it is

necessary to make several distinctions before we can arrive at

what is true and what false in the criticism of introspection.

I wish to distinguish three distinct questions, any one of which

may be meant when we ask whether introspection is a source of

knowledge. The three questions are as follows:

(1) Can we observe anything about ourselves which we cannot

observe about other people, or is everything we can observe

PUBLIC, in the sense that another could also observe it if

suitably placed?

(2) Does everything that we can observe obey the laws of physics

and form part of the physical world, or can we observe certain

things that lie outside physics?

(3) Can we observe anything which differs in its intrinsic nature

from the constituents of the physical world, or is everything

that we can observe composed of elements intrinsically similar to

the constituents of what is called matter?

Any one of these three questions may be used to define

introspection. I should favour introspection in the sense of the

first question, i.e. I think that some of the things we observe

cannot, even theoretically, be observed by any one else. The

second question, tentatively and for the present, I should answer

in favour of introspection; I think that images, in the actual

condition of science, cannot be brought under the causal laws of

physics, though perhaps ultimately they may be. The third

question I should answer adversely to introspection I think that

observation shows us nothing that is not composed of sensations

and images, and that images differ from sensations in their

causal laws, not intrinsically. I shall deal with the three

questions successively.


ourselves, for the moment, to sensations, we find that there are

different degrees of publicity attaching to different sorts of

sensations. If you feel a toothache when the other people in the

room do not, you are in no way surprised; but if you hear a clap

of thunder when they do not, you begin to be alarmed as to your

mental condition. Sight and hearing are the most public of the

senses; smell only a trifle less so; touch, again, a trifle less,

since two people can only touch the same spot successively, not

simultaneously. Taste has a sort of semi-publicity, since people

seem to experience similar taste-sensations when they eat similar

foods; but the publicity is incomplete, since two people cannot

eat actually the same piece of food.

But when we pass on to bodily sensations--headache, toothache,

hunger, thirst, the feeling of fatigue, and so on--we get quite

away from publicity, into a region where other people can tell us

what they feel, but we cannot directly observe their feeling. As

a natural result of this state of affairs, it has come to be

thought that the public senses give us knowledge of the outer

world, while the private senses only give us knowledge as to our

own bodies. As regards privacy, all images, of whatever sort,

belong with the sensations which only give knowledge of our own

bodies, i.e. each is only observable by one observer. This is the

reason why images of sight and hearing are more obviously

different from sensations of sight and hearing than images of

bodily sensations are from bodily sensations; and that is why the

argument in favour of images is more conclusive in such cases as

sight and hearing than in such cases as inner speech.

The whole distinction of privacy and publicity, however, so long

as we confine ourselves to sensations, is one of degree, not of

kind. No two people, there is good empirical reason to think,

ever have exactly similar sensations related to the same physical

object at the same moment; on the other hand, even the most

private sensation has correlations which would theoretically

enable another observer to infer it.

That no sensation is ever completely public, results from

differences of point of view. Two people looking at the same

table do not get the same sensation, because of perspective and

the way the light falls. They get only correlated sensations. Two

people listening to the same sound do not hear exactly the same

thing, because one is nearer to the source of the sound than the

other, one has better hearing than the other, and so on. Thus

publicity in sensations consists, not in having PRECISELY similar

sensations, but in having more or less similar sensations

correlated according to ascertainable laws. The sensations which

strike us as public are those where the correlated sensations are

very similar and the correlations are very easy to discover. But

even the most private sensations have correlations with things

that others can observe. The dentist does not observe your ache,

but he can see the cavity which causes it, and could guess that

you are suffering even if you did not tell him. This fact,

however, cannot be used, as Watson would apparently wish, to

extrude from science observations which are private to one

observer, since it is by means of many such observations that

correlations are established, e.g. between toothaches and

cavities. Privacy, therefore does not by itself make a datum

unamenable to scientific treatment. On this point, the argument

against introspection must be rejected.


now to the second ground of objection to introspection, namely,

that its data do not obey the laws of physics. This, though less

emphasized, is, I think, an objection which is really more

strongly felt than the objection of privacy. And we obtain a

definition of introspection more in harmony with usage if we

define it as observation of data not subject to physical laws

than if we define it by means of privacy. No one would regard a

man as introspective because he was conscious of having a stomach

ache. Opponents of introspection do not mean to deny the obvious

fact that we can observe bodily sensations which others cannot

observe. For example, Knight Dunlap contends that images are

really muscular contractions,* and evidently regards our

awareness of muscular contractions as not coming under the head

of introspection. I think it will be found that the essential

characteristic of introspective data, in the sense which now

concerns us, has to do with LOCALIZATION: either they are not

localized at all, or they are localized, like visual images, in a

place already physically occupied by something which would be

inconsistent with them if they were regarded as part of the

physical world. If you have a visual image of your friend sitting

in a chair which in fact is empty, you cannot locate the image in

your body, because it is visual, nor (as a physical phenomenon)

in the chair, because the chair, as a physical object, is empty.

Thus it seems to follow that the physical world does not include

all that we are aware of, and that images, which are

introspective data, have to be regarded, for the present, as not

obeying the laws of physics; this is, I think, one of the chief

reasons why an attempt is made to reject them. I shall try to

show in Lecture VIII that the purely empirical reasons for

accepting images are overwhelming. But we cannot be nearly so

certain that they will not ultimately be brought under the laws

of physics. Even if this should happen, however, they would still

be distinguishable from sensations by their proximate causal

laws, as gases remain distinguishable from solids.

* "Psychological Review," 1916, "Thought-Content and Feeling," p.

59. See also ib., 1912, "The Nature of Perceived Relations,"

where he says: "'Introspection,' divested of its mythological

suggestion of the observing of consciousness, is really the

observation of bodily sensations (sensibles) and feelings

(feelables)"(p. 427 n.).


SENSATIONS? We come now to our third question concerning

introspection. It is commonly thought that by looking within we

can observe all sorts of things that are radically different from

the constituents of the physical world, e.g. thoughts, beliefs,

desires, pleasures, pains and emotions. The difference between

mind and matter is increased partly by emphasizing these supposed

introspective data, partly by the supposition that matter is

composed of atoms or electrons or whatever units physics may at

the moment prefer. As against this latter supposition, I contend

that the ultimate constituents of matter are not atoms or

electrons, but sensations, and other things similar to sensations

as regards extent and duration. As against the view that

introspection reveals a mental world radically different from

sensations, I propose to argue that thoughts, beliefs, desires,

pleasures, pains and emotions are all built up out of sensations

and images alone, and that there is reason to think that images

do not differ from sensations in their intrinsic character. We

thus effect a mutual rapprochement of mind and matter, and reduce

the ultimate data of introspection (in our second sense) to

images alone. On this third view of the meaning of introspection,

therefore, our decision is wholly against it.

There remain two points to be considered concerning

introspection. The first is as to how far it is trustworthy; the

second is as to whether, even granting that it reveals no

radically different STUFF from that revealed by what might be

called external perception, it may not reveal different

RELATIONS, and thus acquire almost as much importance as is

traditionally assigned to it.

To begin with the trustworthiness of introspection. It is common

among certain schools to regard the knowledge of our own mental

processes as incomparably more certain than our knowledge of the

"external" world; this view is to be found in the British

philosophy which descends from Hume, and is present, somewhat

veiled, in Kant and his followers. There seems no reason whatever

to accept this view. Our spontaneous, unsophisticated beliefs,

whether as to ourselves or as to the outer world, are always

extremely rash and very liable to error. The acquisition of

caution is equally necessary and equally difficult in both

directions. Not only are we often un aware of entertaining a

belief or desire which exists in us; we are often actually

mistaken. The fallibility of introspection as regards what we

desire is made evident by psycho-analysis; its fallibility as to

what we know is easily demonstrated. An autobiography, when

confronted by a careful editor with documentary evidence, is

usually found to be full of obviously inadvertent errors. Any of

us confronted by a forgotten letter written some years ago will

be astonished to find how much more foolish our opinions were

than we had remembered them as being. And as to the analysis of

our mental operations--believing, desiring, willing, or what

not--introspection unaided gives very little help: it is

necessary to construct hypotheses and test them by their

consequences, just as we do in physical science. Introspection,

therefore, though it is one among our sources of knowledge, is

not, in isolation, in any degree more trustworthy than "external"


I come now to our second question: Does introspection give us

materials for the knowledge of relations other than those arrived

at by reflecting upon external perception? It might be contended

that the essence of what is "mental" consists of relations, such

as knowing for example, and that our knowledge concerning these

essentially mental relations is entirely derived from

introspection. If "knowing" were an unanalysable relation, this

view would be incontrovertible, since clearly no such relation

forms part of the subject matter of physics. But it would seem

that "knowing" is really various relations, all of them complex.

Therefore, until they have been analysed, our present question

must remain unanswered I shall return to it at the end of the

present course of lectures.


In Lecture V we found reason to think that the ultimate

constituents* of the world do not have the characteristics of

either mind or matter as ordinarily understood: they are not

solid persistent objects moving through space, nor are they

fragments of "consciousness." But we found two ways of grouping

particulars, one into "things" or "pieces of matter," the other

into series of "perspectives," each series being what may be

called a "biography." Before we can define either sensations or

images, it is necessary to consider this twofold classification

in somewhat greater detail, and to derive from it a definition of

perception. It should be said that, in so far as the

classification assumes the whole world of physics (including its

unperceived portions), it contains hypothetical elements. But we

will not linger on the grounds for admitting these, which belong

to the philosophy of physics rather than of psychology.

* When I speak of "ultimate constituents," I do not mean

necessarily such as are theoretically incapable of analysis, but

only such as, at present, we can see no means of analysing. I

speak of such constituents as "particulars," or as "RELATIVE

particulars" when I wish to emphasize the fact that they may be

themselves complex.

The physical classification of particulars collects together all

those that are aspects of one "thing." Given any one particular,

it is found often (we do not say always) that there are a number

of other particulars differing from this one in gradually

increasing degrees. Those (or some of those) that differ from it

only very slightly will be found to differ approximately

according to certain laws which may be called, in a generalized

sense, the laws of "perspective"; they include the ordinary laws

of perspective as a special case. This approximation grows more

and more nearly exact as the difference grows less; in technical

language, the laws of perspective account for the differences to

the first order of small quantities, and other laws are only

required to account for second-order differences. That is to say,

as the difference diminishes, the part of the difference which is

not according to the laws of perspective diminishes much more

rapidly, and bears to the total difference a ratio which tends

towards zero as both are made smaller and smaller. By this means

we can theoretically collect together a number of particulars

which may be defined as the "aspects" or "appearances" of one

thing at one time. If the laws of perspective were sufficiently

known, the connection between different aspects would be

expressed in differential equations.

This gives us, so far, only those particulars which constitute

one thing at one time. This set of particulars may be called a

"momentary thing." To define that series of "momentary things"

that constitute the successive states of one thing is a problem

involving the laws of dynamics. These give the laws governing the

changes of aspects from one time to a slightly later time, with

the same sort of differential approximation to exactness as we

obtained for spatially neighbouring aspects through the laws of

perspective. Thus a momentary thing is a set of particulars,

while a thing (which may be identified with the whole history of

the thing) is a series of such sets of particulars. The

particulars in one set are collected together by the laws of

perspective; the successive sets are collected together by the

laws of dynamics. This is the view of the world which is

appropriate to traditional physics.

The definition of a "momentary thing" involves problems

concerning time, since the particulars constituting a momentary

thing will not be all simultaneous, but will travel outward from

the thing with the velocity of light (in case the thing is in

vacuo). There are complications connected with relativity, but

for our present purpose they are not vital, and I shall ignore


Instead of first collecting together all the particulars

constituting a momentary thing, and then forming the series of

successive sets, we might have first collected together a series

of successive aspects related by the laws of dynamics, and then

have formed the set of such series related by the laws of

perspective. To illustrate by the case of an actor on the stage:

our first plan was to collect together all the aspects which he

presents to different spectators at one time, and then to form

the series of such sets. Our second plan is first to collect

together all the aspects which he presents successively to a

given spectator, and then to do the same thing for the other

spectators, thus forming a set of series instead of a series of

sets. The first plan tells us what he does; the second the

impressions he produces. This second way of classifying

particulars is one which obviously has more relevance to

psychology than the other. It is partly by this second method of

classification that we obtain definitions of one "experience" or

"biography" or "person." This method of classification is also

essential to the definition of sensations and images, as I shall

endeavour to prove later on. But we must first amplify the

definition of perspectives and biographies.

In our illustration of the actor, we spoke, for the moment, as

though each spectator's mind were wholly occupied by the one

actor. If this were the case, it might be possible to define the

biography of one spectator as a series of successive aspects of

the actor related according to the laws of dynamics. But in fact

this is not the case. We are at all times during our waking life

receiving a variety of impressions, which are aspects of a

variety of things. We have to consider what binds together two

simultaneous sensations in one person, or, more generally, any

two occurrences which forte part of one experience. We might say,

adhering to the standpoint of physics, that two aspects of

different things belong to the same perspective when they are in

the same place. But this would not really help us, since a

"place" has not yet been defined. Can we define what is meant by

saying that two aspects are "in the same place," without

introducing anything beyond the laws of perspective and dynamics?

I do not feel sure whether it is possible to frame such a

definition or not; accordingly I shall not assume that it is

possible, but shall seek other characteristics by which a

perspective or biography may be defined.

When (for example) we see one man and hear another speaking at

the same time, what we see and what we hear have a relation which

we can perceive, which makes the two together form, in some

sense, one experience. It is when this relation exists that two

occurrences become associated. Semon's "engram" is formed by all

that we experience at one time. He speaks of two parts of this

total as having the relation of "Nebeneinander" (M. 118; M.E. 33

ff.), which is reminiscent of Herbart's "Zusammen." I think the

relation may be called simply "simultaneity." It might be said

that at any moment all sorts of things that are not part of my

experience are happening in the world, and that therefore the

relation we are seeking to define cannot be merely simultaneity.

This, however, would be an error--the sort of error that the

theory of relativity avoids. There is not one universal time,

except by an elaborate construction; there are only local times,

each of which may be taken to be the time within one biography.

Accordingly, if I am (say) hearing a sound, the only occurrences

that are, in any simple sense, simultaneous with my sensation are

events in my private world, i.e. in my biography. We may

therefore define the "perspective" to which the sensation in

question belongs as the set of particulars that are simultaneous

with this sensation. And similarly we may define the "biography"

to which the sensation belongs as the set of particulars that are

earlier or later than, or simultaneous with, the given sensation.

Moreover, the very same definitions can be applied to particulars

which are not sensations. They are actually required for the

theory of relativity, if we are to give a philosophical

explanation of what is meant by "local time" in that theory The

relations of simultaneity and succession are known to us in our

own experience; they may be analysable, but that does not affect

their suitability for defining perspectives and biographies. Such

time-relations as can be constructed between events in different

biographies are of a different kind: they are not experienced,

and are merely logical, being designed to afford convenient ways

of stating the correlations between different biographies.

It is not only by time-relations that the parts of one biography

are collected together in the case of living beings. In this case

there are the mnemic phenomena which constitute the unity of one

"experience," and transform mere occurrences into "experiences."

I have already dwelt upon the importance of mnemic phenomena for

psychology, and shall not enlarge upon them now, beyond observing

that they are what transforms a biography (in our technical

sense) into a life. It is they that give the continuity of a

"person" or a "mind." But there is no reason to suppose that

mnemic phenomena are associated with biographies except in the

case of animals and plants.

Our two-fold classification of particulars gives rise to the

dualism of body and biography in regard to everything in the

universe, and not only in regard to living things. This arises as

follows. Every particular of the sort considered by physics is a

member of two groups (1) The group of particulars constituting

the other aspects of the same physical object; (2) The group of

particulars that have direct time-relations to the given


Each of these is associated with a place. When I look at a star,

my sensation is (1) A member of the group of particulars which is

the star, and which is associated with the place where the star

is; (2) A member of the group of particulars which is my

biography, and which is associated with the place where I am.*

*I have explained elsewhere the manner in which space is

constructed on this theory, and in which the position of a

perspective is brought into relation with the position of a

physical object ("Our Knowledge of the External World," Lecture

III, pp. 90, 91).

The result is that every particular of the kind relevant to

physics is associated with TWO places; e.g. my sensation of the

star is associated with the place where I am and with the place

where the star is. This dualism has nothing to do with any "mind"

that I may be supposed to possess; it exists in exactly the same

sense if I am replaced by a photographic plate. We may call the

two places the active and passive places respectively.* Thus in

the case of a perception or photograph of a star, the active

place is the place where the star is, while the passive place is

the place where the percipient or photographic plate is.

* I use these as mere names; I do not want to introduce any

notion of "activity."

We can thus, without departing from physics, collect together all

the particulars actively at a given place, or all the particulars

passively at a given place. In our own case, the one group is our

body (or our brain), while the other is our mind, in so far as it

consists of perceptions. In the case of the photographic plate,

the first group is the plate as dealt with by physics, the second

the aspect of the heavens which it photographs. (For the sake of

schematic simplicity, I am ignoring various complications

connected with time, which require some tedious but perfectly

feasible elaborations.) Thus what may be called subjectivity in

the point of view is not a distinctive peculiarity of mind: it is

present just as much in the photographic plate. And the

photographic plate has its biography as well as its "matter." But

this biography is an affair of physics, and has none of the

peculiar characteristics by which "mental" phenomena are

distinguished, with the sole exception of subjectivity.

Adhering, for the moment, to the standpoint of physics, we may

define a "perception" of an object as the appearance of the

object from a place where there is a brain (or, in lower animals,

some suitable nervous structure), with sense-organs and nerves

forming part of the intervening medium. Such appearances of

objects are distinguished from appearances in other places by

certain peculiarities, namely

(1) They give rise to mnemic phenomena;

(2) They are themselves affected by mnemic phenomena.

That is to say, they may be remembered and associated or

influence our habits, or give rise to images, etc., and they are

themselves different from what they would have been if our past

experience had been different--for example, the effect of a

spoken sentence upon the hearer depends upon whether the hearer

knows the language or not, which is a question of past

experience. It is these two characteristics, both connected with

mnemic phenomena, that distinguish perceptions from the

appearances of objects in places where there is no living being.

Theoretically, though often not practically, we can, in our

perception of an object, separate the part which is due to past

experience from the part which proceeds without mnemic influences

out of the character of the object. We may define as "sensation"

that part which proceeds in this way, while the remainder, which

is a mnemic phenomenon, will have to be added to the sensation to

make up what is called the "perception." According to this

definition, the sensation is a theoretical core in the actual

experience; the actual experience is the perception. It is

obvious that there are grave difficulties in carrying out these

definitions, but we will not linger over them. We have to pass,

as soon as we can, from the physical standpoint, which we have

been hitherto adopting, to the standpoint of psychology, in which

we make more use of introspection in the first of the three

senses discussed in the preceding lecture.

But before making the transition, there are two points which must

be made clear. First: Everything outside my own personal

biography is outside my experience; therefore if anything can be

known by me outside my biography, it can only be known in one of

two ways

(1) By inference from things within my biography, or

(2) By some a priori principle independent of experience.

I do not myself believe that anything approaching certainty is to

be attained by either of these methods, and therefore whatever

lies outside my personal biography must be regarded,

theoretically, as hypothesis. The theoretical argument for

adopting the hypothesis is that it simplifies the statement of

the laws according to which events happen in our experience. But

there is no very good ground for supposing that a simple law is

more likely to be true than a complicated law, though there is

good ground for assuming a simple law in scientific practice, as

a working hypothesis, if it explains the facts as well as another

which is less simple. Belief in the existence of things outside

my own biography exists antecedently to evidence, and can only be

destroyed, if at all, by a long course of philosophic doubt. For

purposes of science, it is justified practically by the

simplification which it introduces into the laws of physics. But

from the standpoint of theoretical logic it must be regarded as a

prejudice, not as a well-grounded theory. With this proviso, I

propose to continue yielding to the prejudice.

The second point concerns the relating of our point of view to

that which regards sensations as caused by stimuli external to

the nervous system (or at least to the brain), and distinguishes

images as "centrally excited," i.e. due to causes in the brain

which cannot be traced back to anything affecting the

sense-organs. It is clear that, if our analysis of physical

objects has been valid, this way of defining sensations needs

reinterpretation. It is also clear that we must be able to find

such a new interpretation if our theory is to be admissible.

To make the matter clear, we will take the simplest possible

illustration. Consider a certain star, and suppose for the moment

that its size is negligible. That is to say, we will regard it

as, for practical purposes, a luminous point. Let us further

suppose that it exists only for a very brief time, say a second.

Then, according to physics, what happens is that a spherical wave

of light travels outward from the star through space, just as,

when you drop a stone into a stagnant pond, ripples travel

outward from the place where the stone hit the water. The wave of

light travels with a certain very nearly constant velocity,

roughly 300,000 kilometres per second. This velocity may be

ascertained by sending a flash of light to a mirror, and

observing how long it takes before the reflected flash reaches

you, just as the velocity of sound may be ascertained by means of

an echo.

What it is that happens when a wave of light reaches a given

place we cannot tell, except in the sole case when the place in

question is a brain connected with an eye which is turned in the

right direction. In this one very special case we know what

happens: we have the sensation called "seeing the star." In all

other cases, though we know (more or less hypothetically) some of

the correlations and abstract properties of the appearance of the

star, we do not know the appearance itself. Now you may, for the

sake of illustration, compare the different appearances of the

star to the conjugation of a Greek verb, except that the number

of its parts is really infinite, and not only apparently so to

the despairing schoolboy. In vacuo, the parts are regular, and

can be derived from the (imaginary) root according to the laws of

grammar, i.e. of perspective. The star being situated in empty

space, it may be defined, for purposes of physics, as consisting

of all those appearances which it presents in vacuo, together

with those which, according to the laws of perspective, it would

present elsewhere if its appearances elsewhere were regular. This

is merely the adaptation of the definition of matter which I gave

in an earlier lecture. The appearance of a star at a certain

place, if it is regular, does not require any cause or

explanation beyond the existence of the star. Every regular

appearance is an actual member of the system which is the star,

and its causation is entirely internal to that system. We may

express this by saying that a regular appearance is due to the

star alone, and is actually part of the star, in the sense in

which a man is part of the human race.

But presently the light of the star reaches our atmosphere. It

begins to be refracted, and dimmed by mist, and its velocity is

slightly diminished. At last it reaches a human eye, where a

complicated process takes place, ending in a sensation which

gives us our grounds for believing in all that has gone before.

Now, the irregular appearances of the star are not, strictly

speaking, members of the system which is the star, according to

our definition of matter. The irregular appearances, however, are

not merely irregular: they proceed according to laws which can be

stated in terms of the matter through which the light has passed

on its way. The sources of an irregular appearance are therefore


(1) The object which is appearing irregularly;

2) The intervening medium.

It should be observed that, while the conception of a regular

appearance is perfectly precise, the conception of an irregular

appearance is one capable of any degree of vagueness. When the

distorting influence of the medium is sufficiently great, the

resulting particular can no longer be regarded as an appearance

of an object, but must be treated on its own account. This

happens especially when the particular in question cannot be

traced back to one object, but is a blend of two or more. This

case is normal in perception: we see as one what the microscope

or telescope reveals to be many different objects. The notion of

perception is therefore not a precise one: we perceive things

more or less, but always with a very considerable amount of

vagueness and confusion.

In considering irregular appearances, there are certain very

natural mistakes which must be avoided. In order that a

particular may count as an irregular appearance of a certain

object, it is not necessary that it should bear any resemblance

to the regular appearances as regard its intrinsic qualities. All

that is necessary is that it should be derivable from the regular

appearances by the laws which express the distorting influence of

the medium. When it is so derivable, the particular in question

may be regarded as caused by the regular appearances, and

therefore by the object itself, together with the modifications

resulting from the medium. In other cases, the particular in

question may, in the same sense, be regarded as caused by several

objects together with the medium; in this case, it may be called

a confused appearance of several objects. If it happens to be in

a brain, it may be called a confused perception of these objects.

All actual perception is confused to a greater or less extent.

We can now interpret in terms of our theory the distinction

between those mental occurrences which are said to have an

external stimulus, and those which are said to be "centrally

excited," i.e. to have no stimulus external to the brain. When a

mental occurrence can be regarded as an appearance of an object

external to the brain, however irregular, or even as a confused

appearance of several such objects, then we may regard it as

having for its stimulus the object or objects in question, or

their appearances at the sense-organ concerned. When, on the

other hand, a mental occurrence has not sufficient connection

with objects external to the brain to be regarded as an

appearance of such objects, then its physical causation (if any)

will have to be sought in the brain. In the former case it can be

called a perception; in the latter it cannot be so called. But

the distinction is one of degree, not of kind. Until this is

realized, no satisfactory theory of perception, sensation, or

imagination is possible.


The dualism of mind and matter, if we have been right so far,

cannot be allowed as metaphysically valid. Nevertheless, we seem

to find a certain dualism, perhaps not ultimate, within the world

as we observe it. The dualism is not primarily as to the stuff of

the world, but as to causal laws. On this subject we may again

quote William James. He points out that when, as we say, we

merely "imagine" things, there are no such effects as would ensue

if the things were what we call "real." He takes the case of

imagining a fire

"I make for myself an experience of blazing fire; I place it near

my body; but it does not warm me in the least. I lay a stick upon

it and the stick either burns or remains green, as I please. I

call up water, and pour it on the fire, and absolutely no

difference ensues. I account for all such facts by calling this

whole train of experiences unreal, a mental train. Mental fire is

what won't burn real sticks; mental water is what won't

necessarily (though of course it may) put out even a mental

fire.... With 'real' objects, on the contrary, consequences

always accrue; and thus the real experiences get sifted from the

mental ones, the things from our thoughts of them, fanciful or

true, and precipitated together as the stable part of the whole

experience--chaos, under the name of the physical world."*

* "Essays in Radical Empiricism," pp. 32-3.

In this passage James speaks, by mere inadvertence, as though the

phenomena which he is describing as "mental" had NO effects. This

is, of course, not the case: they have their effects, just as

much as physical phenomena do, but their effects follow different

laws. For example, dreams, as Freud has shown, are just as much

subject to laws as are the motions of the planets. But the laws

are different: in a dream you may be transported from one place

to another in a moment, or one person may turn into another under

your eyes. Such differences compel you to distinguish the world

of dreams from the physical world.

If the two sorts of causal laws could be sharply distinguished,

we could call an occurrence "physical" when it obeys causal laws

appropriate to the physical world, and "mental" when it obeys

causal laws appropriate to the mental world. Since the mental

world and the physical world interact, there would be a boundary

between the two: there would be events which would have physical

causes and mental effects, while there would be others which

would have mental causes and physical effects. Those that have

physical causes and mental effects we should define as

"sensations." Those that have mental causes and physical effects

might perhaps be identified with what we call voluntary

movements; but they do not concern us at present.

These definitions would have all the precision that could be

desired if the distinction between physical and psychological

causation were clear and sharp. As a matter of fact, however,

this distinction is, as yet, by no means sharp. It is possible

that, with fuller knowledge, it will be found to be no more

ultimate than the distinction between the laws of gases and the

laws of rigid bodies. It also suffers from the fact that an event

may be an effect of several causes according to several causal

laws we cannot, in general, point to anything unique as THE cause

of such-and-such an event. And finally it is by no means certain

that the peculiar causal laws which govern mental events are not

really physiological. The law of habit, which is one of the most

distinctive, may be fully explicable in terms of the

peculiarities of nervous tissue, and these peculiarities, in

turn, may be explicable by the laws of physics. It seems,

therefore, that we are driven to a different kind of definition.

It is for this reason that it was necessary to develop the

definition of perception. With this definition, we can define a

sensation as the non-mnemic elements in a perception.

When, following our definition, we try to decide what elements in

our experience are of the nature of sensations, we find more

difficulty than might have been expected. Prima facie, everything

is sensation that comes to us through the senses: the sights we

see, the sounds we hear, the smells we smell, and so on; also

such things as headache or the feeling of muscular strain. But in

actual fact so much interpretation, so much of habitual

correlation, is mixed with all such experiences, that the core of

pure sensation is only to be extracted by careful investigation.

To take a simple illustration: if you go to the theatre in your

own country, you seem to hear equally well in the stalls or the

dress circle; in either case you think you miss nothing. But if

you go in a foreign country where you have a fair knowledge of

the language, you will seem to have grown partially deaf, and you

will find it necessary to be much nearer the stage than you would

need to be in your own country. The reason is that, in hearing

our own language spoken, we quickly and unconsciously fill out

what we really hear with inferences to what the man must be

saying, and we never realize that we have not heard the words we

have merely inferred. In a foreign language, these inferences are

more difficult, and we are more dependent upon actual sensation.

If we found ourselves in a foreign world, where tables looked

like cushions and cushions like tables, we should similarly

discover how much of what we think we see is really inference.

Every fairly familiar sensation is to us a sign of the things

that usually go with it, and many of these things will seem to

form part of the sensation. I remember in the early days of

motor-cars being with a friend when a tyre burst with a loud

report. He thought it was a pistol, and supported his opinion by

maintaining that he had seen the flash. But of course there had

been no flash. Nowadays no one sees a flash when a tyre bursts.

In order, therefore, to arrive at what really is sensation in an

occurrence which, at first sight, seems to contain nothing else,

we have to pare away all that is due to habit or expectation or

interpretation. This is a matter for the psychologist, and by no

means an easy matter. For our purposes, it is not important to

determine what exactly is the sensational core in any case; it is

only important to notice that there certainly is a sensational

core, since habit, expectation and interpretation are diversely

aroused on diverse occasions, and the diversity is clearly due to

differences in what is presented to the senses. When you open

your newspaper in the morning, the actual sensations of seeing

the print form a very minute part of what goes on in you, but

they are the starting-point of all the rest, and it is through

them that the newspaper is a means of information or

mis-information. Thus, although it may be difficult to determine

what exactly is sensation in any given experience, it is clear

that there is sensation, unless, like Leibniz, we deny all action

of the outer world upon us.

Sensations are obviously the source of our knowledge of the

world, including our own body. It might seem natural to regard a

sensation as itself a cognition, and until lately I did so regard

it. When, say, I see a person I know coming towards me in the

street, it SEEMS as though the mere seeing were knowledge. It is

of course undeniable that knowledge comes THROUGH the seeing, but

I think it is a mistake to regard the mere seeing itself as

knowledge. If we are so to regard it, we must distinguish the

seeing from what is seen: we must say that, when we see a patch

of colour of a certain shape, the patch of colour is one thing

and our seeing of it is another. This view, however, demands the

admission of the subject, or act, in the sense discussed in our

first lecture. If there is a subject, it can have a relation to

the patch of colour, namely, the sort of relation which we might

call awareness. In that case the sensation, as a mental event,

will consist of awareness of the colour, while the colour itself

will remain wholly physical, and may be called the sense-datum,

to distinguish it from the sensation. The subject, however,

appears to be a logical fiction, like mathematical points and

instants. It is introduced, not because observation reveals it,

but because it is linguistically convenient and apparently

demanded by grammar. Nominal entities of this sort may or may not

exist, but there is no good ground for assuming that they do. The

functions that they appear to perform can always be performed by

classes or series or other logical constructions, consisting of

less dubious entities. If we are to avoid a perfectly gratuitous

assumption, we must dispense with the subject as one of the

actual ingredients of the world. But when we do this, the

possibility of distinguishing the sensation from the sense-datum

vanishes; at least I see no way of preserving the distinction.

Accordingly the sensation that we have when we see a patch of

colour simply is that patch of colour, an actual constituent of

the physical world, and part of what physics is concerned with. A

patch of colour is certainly not knowledge, and therefore we

cannot say that pure sensation is cognitive. Through its

psychological effects, it is the cause of cognitions, partly by

being itself a sign of things that are correlated with it, as

e.g. sensations of sight and touch are correlated, and partly by

giving rise to images and memories after the sensation is faded.

But in itself the pure sensation is not cognitive.

In the first lecture we considered the view of Brentano, that "we

may define psychical phenomena by saying that they are phenomena

which intentionally contain an object." We saw reasons to reject

this view in general; we are now concerned to show that it must

be rejected in the particular case of sensations. The kind of

argument which formerly made me accept Brentano's view in this

case was exceedingly simple. When I see a patch of colour, it

seemed to me that the colour is not psychical, but physical,

while my seeing is not physical, but psychical. Hence I concluded

that the colour is something other than my seeing of the colour.

This argument, to me historically, was directed against idealism:

the emphatic part of it was the assertion that the colour is

physical, not psychical. I shall not trouble you now with the

grounds for holding as against Berkeley that the patch of colour

is physical; I have set them forth before, and I see no reason to

modify them. But it does not follow that the patch of colour is

not also psychical, unless we assume that the physical and the

psychical cannot overlap, which I no longer consider a valid

assumption. If we admit--as I think we should--that the patch of

colour may be both physical and psychical, the reason for

distinguishing the sense-datum from the sensation disappears, and

we may say that the patch of colour and our sensation in seeing

it are identical.

This is the view of William James, Professor Dewey, and the

American realists. Perceptions, says Professor Dewey, are not per

se cases of knowledge, but simply natural events with no more

knowledge status than (say) a shower. "Let them [the realists]

try the experiment of conceiving perceptions as pure natural

events, not cases of awareness or apprehension, and they will be

surprised to see how little they miss."* I think he is right in

this, except in supposing that the realists will be surprised.

Many of them already hold the view he is advocating, and others

are very sympathetic to it. At any rate, it is the view which I

shall adopt in these lectures.

* Dewey, "Essays in Experimental Logic," pp. 253, 262.

The stuff of the world, so far as we have experience of it,

consists, on the view that I am advocating, of innumerable

transient particulars such as occur in seeing, hearing, etc.,

together with images more or less resembling these, of which I

shall speak shortly. If physics is true, there are, besides the

particulars that we experience, others, probably equally (or

almost equally) transient, which make up that part of the

material world that does not come into the sort of contact with a

living body that is required to turn it into a sensation. But

this topic belongs to the philosophy of physics, and need not

concern us in our present inquiry.

Sensations are what is common to the mental and physical worlds;

they may be defined as the intersection of mind and matter. This

is by no means a new view; it is advocated, not only by the

American authors I have mentioned, but by Mach in his Analysis of

Sensations, which was published in 1886. The essence of

sensation, according to the view I am advocating, is its

independence of past experience. It is a core in our actual

experiences, never existing in isolation except possibly in very

young infants. It is not itself knowledge, but it supplies the

data for our knowledge of the physical world, including our own


There are some who believe that our mental life is built up out

of sensations alone. This may be true; but in any case I think

the only ingredients required in addition to sensations are

images. What images are, and how they are to be defined, we have

now to inquire.

The distinction between images and sensations might seem at first

sight by no means difficult. When we shut our eyes and call up

pictures of familiar scenes, we usually have no difficulty, so

long as we remain awake, in discriminating between what we are

imagining and what is really seen. If we imagine some piece of

music that we know, we can go through it in our mind from

beginning to end without any discoverable tendency to suppose

that we are really hearing it. But although such cases are so

clear that no confusion seems possible, there are many others

that are far more difficult, and the definition of images is by

no means an easy problem.

To begin with: we do not always know whether what we are

experiencing is a sensation or an image. The things we see in

dreams when our eyes are shut must count as images, yet while we

are dreaming they seem like sensations. Hallucinations often

begin as persistent images, and only gradually acquire that

influence over belief that makes the patient regard them as

sensations. When we are listening for a faint sound--the striking

of a distant clock, or a horse's hoofs on the road--we think we

hear it many times before we really do, because expectation

brings us the image, and we mistake it for sensation. The

distinction between images and sensations is, therefore, by no

means always obvious to inspection.*

* On the distinction between images and sensation, cf. Semon,

"Die mnemischen Empfindungen," pp. 19-20.

We may consider three different ways in which it has been sought

to distinguish images from sensations, namely:

(1) By the less degree of vividness in images;

(2) By our absence of belief in their "physical reality";

(3) By the fact that their causes and effects are different from

those of sensations.

I believe the third of these to be the only universally

applicable criterion. The other two are applicable in very many

cases, but cannot be used for purposes of definition because they

are liable to exceptions. Nevertheless, they both deserve to be

carefully considered.

(1) Hume, who gives the names "impressions" and "ideas" to what

may, for present purposes, be identified with our "sensations"

and "images," speaks of impressions as "those perceptions which

enter with most force and violence" while he defines ideas as

"the faint images of these (i.e. of impressions) in thinking and

reasoning." His immediately following observations, however, show

the inadequacy of his criteria of "force" and "faintness." He


"I believe it will not be very necessary to employ many words in

explaining this distinction. Every one of himself will readily

perceive the difference betwixt feeling and thinking. The common

degrees of these are easily distinguished, though it is not

impossible but in particular instances they may very nearly

approach to each other. Thus in sleep, in a fever, in madness, or

in any very violent emotions of soul, our ideas may approach to

our impressions; as, on the other hand, it sometimes happens,

that our impressions are so faint and low that we cannot

distinguish them from our ideas. But notwithstanding this near

resemblance in a few instances, they are in general so very

different, that no one can make a scruple to rank them under

distinct heads, and assign to each a peculiar name to mark the

difference" ("Treatise of Human Nature," Part I, Section I).

I think Hume is right in holding that they should be ranked under

distinct heads, with a peculiar name for each. But by his own

confession in the above passage, his criterion for distinguishing

them is not always adequate. A definition is not sound if it only

applies in cases where the difference is glaring: the essential

purpose of a definition is to provide a mark which is applicable

even in marginal cases--except, of course, when we are dealing

with a conception, like, e.g. baldness, which is one of degree

and has no sharp boundaries. But so far we have seen no reason to

think that the difference between sensations and images is only

one of degree.

Professor Stout, in his "Manual of Psychology," after discussing

various ways of distinguishing sensations and images, arrives at

a view which is a modification of Hume's. He says (I quote from

the second edition):

"Our conclusion is that at bottom the distinction between image

and percept, as respectively faint and vivid states, is based on

a difference of quality. The percept has an aggressiveness which

does not belong to the image. It strikes the mind with varying

degrees of force or liveliness according to the varying intensity

of the stimulus. This degree of force or liveliness is part of

what we ordinarily mean by the intensity of a sensation. But this

constituent of the intensity of sensations is absent in mental

imagery"(p. 419).

This view allows for the fact that sensations may reach any

degree of faintness--e.g. in the case of a just visible star or a

just audible sound--without becoming images, and that therefore

mere faintness cannot be the characteristic mark of images. After

explaining the sudden shock of a flash of lightning or a

steam-whistle, Stout says that "no mere image ever does strike

the mind in this manner"(p. 417). But I believe that this

criterion fails in very much the same instances as those in which

Hume's criterion fails in its original form. Macbeth speaks of--

that suggestion Whose horrid image doth unfix my

hair And make my seated heart knock at my ribs Against

the use of nature.

The whistle of a steam-engine could hardly have a stronger effect

than this. A very intense emotion will often bring with

it--especially where some future action or some undecided issue

is involved--powerful compelling images which may determine the

whole course of life, sweeping aside all contrary solicitations

to the will by their capacity for exclusively possessing the

mind. And in all cases where images, originally recognized as

such, gradually pass into hallucinations, there must be just that

"force or liveliness" which is supposed to be always absent from

images. The cases of dreams and fever-delirium are as hard to

adjust to Professor Stout's modified criterion as to Hume's. I

conclude therefore that the test of liveliness, however

applicable in ordinary instances, cannot be used to define the

differences between sensations and images.

(2) We might attempt to distinguish images from sensations by our

absence of belief in the "physical reality" of images. When we

are aware that what we are experiencing is an image, we do not

give it the kind of belief that we should give to a sensation: we

do not think that it has the same power of producing knowledge of

the "external world." Images are "imaginary"; in SOME sense they

are "unreal." But this difference is hard to analyse or state

correctly. What we call the "unreality" of images requires

interpretation it cannot mean what would be expressed by saying

"there's no such thing." Images are just as truly part of the

actual world as sensations are. All that we really mean by

calling an image "unreal" is that it does not have the

concomitants which it would have if it were a sensation. When we

call up a visual image of a chair, we do not attempt to sit in

it, because we know that, like Macbeth's dagger, it is not

"sensible to feeling as to sight"-- i.e. it does not have the

correlations with tactile sensations which it would have if it

were a visual sensation and not merely a visual image. But this

means that the so-called "unreality" of images consists merely in

their not obeying the laws of physics, and thus brings us back to

the causal distinction between images and sensations.

This view is confirmed by the fact that we only feel images to be

"unreal" when we already know them to be images. Images cannot be

defined by the FEELING of unreality, because when we falsely

believe an image to be a sensation, as in the case of dreams, it

FEELS just as real as if it were a sensation. Our feeling of

unreality results from our having already realized that we are

dealing with an image, and cannot therefore be the definition of

what we mean by an image. As soon as an image begins to deceive

us as to its status, it also deceives us as to its correlations,

which are what we mean by its "reality."

(3) This brings us to the third mode of distinguishing images

from sensations, namely, by their causes and effects. I believe

this to be the only valid ground of distinction. James, in the

passage about the mental fire which won't burn real sticks,

distinguishes images by their effects, but I think the more

reliable distinction is by their causes. Professor Stout (loc.

cit., p. 127) says: "One characteristic mark of what we agree in

calling sensation is its mode of production. It is caused by what

we call a STIMULUS. A stimulus is always some condition external

to the nervous system itself and operating upon it." I think that

this is the correct view, and that the distinction between images

and sensations can only be made by taking account of their

causation. Sensations come through sense-organs, while images do

not. We cannot have visual sensations in the dark, or with our

eyes shut, but we can very well have visual images under these

circumstances. Accordingly images have been defined as "centrally

excited sensations," i.e. sensations which have their

physiological cause in the brain only, not also in the

sense-organs and the nerves that run from the sense-organs to the

brain. I think the phrase "centrally excited sensations" assumes

more than is necessary, since it takes it for granted that an

image must have a proximate physiological cause. This is probably

true, but it is an hypothesis, and for our purposes an

unnecessary one. It would seem to fit better with what we can

immediately observe if we were to say that an image is

occasioned, through association, by a sensation or another image,

in other words that it has a mnemic cause--which does not prevent

it from also having a physical cause. And I think it will be

found that the causation of an image always proceeds according to

mnemic laws, i.e. that it is governed by habit and past

experience. If you listen to a man playing the pianola without

looking at him, you will have images of his hands on the keys as

if he were playing the piano; if you suddenly look at him while

you are absorbed in the music, you will experience a shock of

surprise when you notice that his hands are not touching the

notes. Your image of his hands is due to the many times that you

have heard similar sounds and at the same time seen the player's

hands on the piano. When habit and past experience play this

part, we are in the region of mnemic as opposed to ordinary

physical causation. And I think that, if we could regard as

ultimately valid the difference between physical and mnemic

causation, we could distinguish images from sensations as having

mnemic causes, though they may also have physical causes.

Sensations, on the other hand, will only have physical causes.

However this may be, the practically effective distinction

between sensations and images is that in the causation of

sensations, but not of images, the stimulation of nerves carrying

an effect into the brain, usually from the surface of the body,

plays an essential part. And this accounts for the fact that

images and sensations cannot always be distinguished by their

intrinsic nature.

Images also differ from sensations as regards their effects.

Sensations, as a rule, have both physical and mental effects. As

you watch the train you meant to catch leaving the station, there

are both the successive positions of the train (physical effects)

and the successive waves of fury and disappointment (mental

effects). Images, on the contrary, though they MAY produce bodily

movements, do so according to mnemic laws, not according to the

laws of physics. All their effects, of whatever nature, follow

mnemic laws. But this difference is less suitable for definition

than the difference as to causes.

Professor Watson, as a logical carrying-out of his behaviourist

theory, denies altogether that there are any observable phenomena

such as images are supposed to be. He replaces them all by faint

sensations, and especially by pronunciation of words sotto voce.

When we "think" of a table (say), as opposed to seeing it, what

happens, according to him, is usually that we are making small

movements of the throat and tongue such as would lead to our

uttering the word "table" if they were more pronounced. I shall

consider his view again in connection with words; for the present

I am only concerned to combat his denial of images. This denial

is set forth both in his book on "Behavior" and in an article

called "Image and Affection in Behavior" in the "Journal of

Philosophy, Psychology and Scientific Methods," vol. x (July,

1913). It seems to me that in this matter he has been betrayed

into denying plain facts in the interests of a theory, namely,

the supposed impossibility of introspection. I dealt with the

theory in Lecture VI; for the present I wish to reinforce the

view that the facts are undeniable.

Images are of various sorts, according to the nature of the

sensations which they copy. Images of bodily movements, such as

we have when we imagine moving an arm or, on a smaller scale,

pronouncing a word, might possibly be explained away on Professor

Watson's lines, as really consisting in small incipient movements

such as, if magnified and prolonged, would be the movements we

are said to be imagining. Whether this is the case or not might

even be decided experimentally. If there were a delicate

instrument for recording small movements in the mouth and throat,

we might place such an instrument in a person's mouth and then

tell him to recite a poem to himself, as far as possible only in

imagination. I should not be at all surprised if it were found

that actual small movements take place while he is "mentally"

saying over the verses. The point is important, because what is

called "thought" consists mainly (though I think not wholly) of

inner speech. If Professor Watson is right as regards inner

speech, this whole region is transferred from imagination to

sensation. But since the question is capable of experimental

decision, it would be gratuitous rashness to offer an opinion

while that decision is lacking.

But visual and auditory images are much more difficult to deal

with in this way, because they lack the connection with physical

events in the outer world which belongs to visual and auditory

sensations. Suppose, for example, that I am sitting in my room,

in which there is an empty arm-chair. I shut my eyes, and call up

a visual image of a friend sitting in the arm-chair. If I thrust

my image into the world of physics, it contradicts all the usual

physical laws. My friend reached the chair without coming in at

the door in the usual way; subsequent inquiry will show that he

was somewhere else at the moment. If regarded as a sensation, my

image has all the marks of the supernatural. My image, therefore,

is regarded as an event in me, not as having that position in the

orderly happenings of the public world that belongs to

sensations. By saying that it is an event in me, we leave it

possible that it may be PHYSIOLOGICALLY caused: its privacy may

be only due to its connection with my body. But in any case it is

not a public event, like an actual person walking in at the door

and sitting down in my chair. And it cannot, like inner speech,

be regarded as a SMALL sensation, since it occupies just as large

an area in my visual field as the actual sensation would do.

Professor Watson says: "I should throw out imagery altogether and

attempt to show that all natural thought goes on in terms of

sensori-motor processes in the larynx." This view seems to me

flatly to contradict experience. If you try to persuade any

uneducated person that she cannot call up a visual picture of a

friend sitting in a chair, but can only use words describing what

such an occurrence would be like, she will conclude that you are

mad. (This statement is based upon experiment.) Galton, as every

one knows, investigated visual imagery, and found that education

tends to kill it: the Fellows of the Royal Society turned out to

have much less of it than their wives. I see no reason to doubt

his conclusion that the habit of abstract pursuits makes learned

men much inferior to the average in power of visualizing, and

much more exclusively occupied with words in their "thinking."

And Professor Watson is a very learned man.

I shall henceforth assume that the existence of images is

admitted, and that they are to be distinguished from sensations

by their causes, as well as, in a lesser degree, by their

effects. In their intrinsic nature, though they often differ from

sensations by being more dim or vague or faint, yet they do not

always or universally differ from sensations in any way that can

be used for defining them. Their privacy need form no bar to the

scientific study of them, any more than the privacy of bodily

sensations does. Bodily sensations are admitted by even the most

severe critics of introspection, although, like images, they can

only be observed by one observer. It must be admitted, however,

that the laws of the appearance and disappearance of images are

little known and difficult to discover, because we are not

assisted, as in the case of sensations, by our knowledge of the

physical world.

There remains one very important point concerning images, which

will occupy us much hereafter, and that is, their resemblance to

previous sensations. They are said to be "copies" of sensations,

always as regards the simple qualities that enter into them,

though not always as regards the manner in which these are put

together. It is generally believed that we cannot imagine a shade

of colour that we have never seen, or a sound that we have never

heard. On this subject Hume is the classic. He says, in the

definitions already quoted:

"Those perceptions, which enter with most force and violence, we

may name IMPRESSIONS; and under this name I comprehend all our

sensations, passions and emotions, as they make their first

appearance in the soul. By IDEAS I mean the faint images of these

in thinking and reasoning."

He next explains the difference between simple and complex ideas,

and explains that a complex idea may occur without any similar

complex impression. But as regards simple ideas, he states that

"every simple idea has a simple impression, which resembles it,

and every simple impression a correspondent idea." He goes on to

enunciate the general principle "that all our simple ideas in

their first appearance are derived from simple impressions, which

are correspondent to them, and which they exactly represent"

("Treatise of Human Nature," Part I, Section I).

It is this fact, that images resemble antecedent sensations,

which enables us to call them images "of" this or that. For the

understanding of memory, and of knowledge generally, the

recognizable resemblance of images and sensations is of

fundamental importance.

There are difficulties in establishing Hume's principles, and

doubts as to whether it is exactly true. Indeed, he himself

signalized an exception immediately after stating his maxim.

Nevertheless, it is impossible to doubt that in the main simple

images are copies of similar simple sensations which have

occurred earlier, and that the same is true of complex images in

all cases of memory as opposed to mere imagination. Our power of

acting with reference to what is sensibly absent is largely due

to this characteristic of images, although, as education

advances, images tend to be more and more replaced by words. We

shall have much to say in the next two lectures on the subject of

images as copies of sensations. What has been said now is merely

by way of reminder that this is their most notable


I am by no means confident that the distinction between images

and sensations is ultimately valid, and I should be glad to be

convinced that images can be reduced to sensations of a peculiar

kind. I think it is clear, however, that, at any rate in the case

of auditory and visual images, they do differ from ordinary

auditory and visual sensations, and therefore form a recognizable

class of occurrences, even if it should prove that they can be

regarded as a sub-class of sensations. This is all that is

necessary to validate the use of images to be made in the sequel.


Memory, which we are to consider to-day, introduces us to

knowledge in one of its forms. The analysis of knowledge will

occupy us until the end of the thirteenth lecture, and is the

most difficult part of our whole enterprise.

I do not myself believe that the analysis of knowledge can be

effected entirely by means of purely external observation, such

as behaviourists employ. I shall discuss this question in later

lectures. In the present lecture I shall attempt the analysis of

memory-knowledge, both as an introduction to the problem of

knowledge in general, and because memory, in some form, is

presupposed in almost all other knowledge. Sensation, we decided,

is not a form of knowledge. It might, however, have been expected

that we should begin our discussion of knowledge with PERCEPTION,

i.e. with that integral experience of things in the environment,

out of which sensation is extracted by psychological analysis.

What is called perception differs from sensation by the fact that

the sensational ingredients bring up habitual associates--images

and expectations of their usual correlates--all of which are

subjectively indistinguishable from the sensation. The FACT of

past experience is essential in producing this filling-out of

sensation, but not the RECOLLECTION of past experience. The

non-sensational elements in perception can be wholly explained as

the result of habit, produced by frequent correlations.

Perception, according to our definition in Lecture VII, is no

more a form of knowledge than sensation is, except in so far as

it involves expectations. The purely psychological problems which

it raises are not very difficult, though they have sometimes been

rendered artificially obscure by unwillingness to admit the

fallibility of the non-sensational elements of perception. On the

other hand, memory raises many difficult and very important

problems, which it is necessary to consider at the first possible


One reason for treating memory at this early stage is that it

seems to be involved in the fact that images are recognized as

"copies" of past sensible experience. In the preceding lecture I

alluded to Hume's principle "that all our simple ideas in their

first appearance are derived from simple impressions, which are

correspondent to them, and which they exactly represent." Whether

or not this principle is liable to exceptions, everyone would

agree that is has a broad measure of truth, though the word

"exactly" might seem an overstatement, and it might seem more

correct to say that ideas APPROXIMATELY represent impressions.

Such modifications of Hume's principle, however, do not affect

the problem which I wish to present for your consideration,

namely: Why do we believe that images are, sometimes or always,

approximately or exactly, copies of sensations? What sort of

evidence is there? And what sort of evidence is logically

possible? The difficulty of this question arises through the fact

that the sensation which an image is supposed to copy is in the

past when the image exists, and can therefore only be known by

memory, while, on the other hand, memory of past sensations seems

only possible by means of present images. How, then, are we to

find any way of comparing the present image and the past

sensation? The problem is just as acute if we say that images

differ from their prototypes as if we say that they resemble

them; it is the very possibility of comparison that is hard to

understand.* We think we can know that they are alike or

different, but we cannot bring them together in one experience

and compare them. To deal with this problem, we must have a

theory of memory. In this way the whole status of images as

"copies" is bound up with the analysis of memory.

* How, for example, can we obtain such knowledge as the

following: "If we look at, say, a red nose and perceive it, and

after a little while ekphore, its memory-image, we note

immediately how unlike, in its likeness, this memory-image is to

the original perception" (A. Wohlgemuth, "On the Feelings and

their Neural Correlate with an Examination of the Nature of

Pain," "Journal of Psychology," vol. viii, part iv, June, 1917).

In investigating memory-beliefs, there are certain points which

must be borne in mind. In the first place, everything

constituting a memory-belief is happening now, not in that past

time to which the belief is said to refer. It is not logically

necessary to the existence of a memory-belief that the event

remembered should have occurred, or even that the past should

have existed at all. There is no logical impossibility in the

hypothesis that the world sprang into being five minutes ago,

exactly as it then was, with a population that "remembered" a

wholly unreal past. There is no logically necessary connection

between events at different times; therefore nothing that is

happening now or will happen in the future can disprove the

hypothesis that the world began five minutes ago. Hence the

occurrences which are CALLED knowledge of the past are logically

independent of the past; they are wholly analysable into present

contents, which might, theoretically, be just what they are even

if no past had existed.

I am not suggesting that the non-existence of the past should be

entertained as a serious hypothesis. Like all sceptical

hypotheses, it is logically tenable, but uninteresting. All that

I am doing is to use its logical tenability as a help in the

analysis of what occurs when we remember.

In the second place, images without beliefs are insufficient to

constitute memory; and habits are still more insufficient. The

behaviourist, who attempts to make psychology a record of

behaviour, has to trust his memory in making the record. "Habit"

is a concept involving the occurrence of similar events at

different times; if the behaviourist feels confident that there

is such a phenomenon as habit, that can only be because he trusts

his memory, when it assures him that there have been other times.

And the same applies to images. If we are to know as it is

supposed we do--that images are "copies," accurate or inaccurate,

of past events, something more than the mere occurrence of images

must go to constitute this knowledge. For their mere occurrence,

by itself, would not suggest any connection with anything that

had happened before.

Can we constitute memory out of images together with suitable

beliefs? We may take it that memory-images, when they occur in

true memory, are (a) known to be copies, (b) sometimes known to

be imperfect copies (cf. footnote on previous page). How is it

possible to know that a memory-image is an imperfect copy,

without having a more accurate copy by which to replace it? This

would SEEM to suggest that we have a way of knowing the past

which is independent of images, by means of which we can

criticize image-memories. But I do not think such an inference is


What results, formally, from our knowledge of the past through

images of which we recognize the inaccuracy, is that such images

must have two characteristics by which we can arrange them in two

series, of which one corresponds to the more or less remote

period in the past to which they refer, and the other to our

greater or less confidence in their accuracy. We will take the

second of these points first.

Our confidence or lack of confidence in the accuracy of a

memory-image must, in fundamental cases, be based upon a

characteristic of the image itself, since we cannot evoke the

past bodily and compare it with the present image. It might be

suggested that vagueness is the required characteristic, but I do

not think this is the case. We sometimes have images that are by

no means peculiarly vague, which yet we do not trust--for

example, under the influence of fatigue we may see a friend's

face vividly and clearly, but horribly distorted. In such a case

we distrust our image in spite of its being unusually clear. I

think the characteristic by which we distinguish the images we

trust is the feeling of FAMILIARITY that accompanies them. Some

images, like some sensations, feel very familiar, while others

feel strange. Familiarity is a feeling capable of degrees. In an

image of a well-known face, for example, some parts may feel more

familiar than others; when this happens, we have more belief in

the accuracy of the familiar parts than in that of the unfamiliar

parts. I think it is by this means that we become critical of

images, not by some imageless memory with which we compare them.

I shall return to the consideration of familiarity shortly.

I come now to the other characteristic which memory-images must

have in order to account for our knowledge of the past. They must

have some characteristic which makes us regard them as referring

to more or less remote portions of the past. That is to say if we

suppose that A is the event remembered, B the remembering, and t

the interval of time between A and B, there must be some

characteristic of B which is capable of degrees, and which, in

accurately dated memories, varies as t varies. It may increase as

t increases, or diminish as t increases. The question which of

these occurs is not of any importance for the theoretic

serviceability of the characteristic in question.

In actual fact, there are doubtless various factors that concur

in giving us the feeling of greater or less remoteness in some

remembered event. There may be a specific feeling which could be

called the feeling of "pastness," especially where immediate

memory is concerned. But apart from this, there are other marks.

One of these is context. A recent memory has, usually, more

context than a more distant one. When a remembered event has a

remembered context, this may occur in two ways, either (a) by

successive images in the same order as their prototypes, or (b)

by remembering a whole process simultaneously, in the same way in

which a present process may be apprehended, through akoluthic

sensations which, by fading, acquire the mark of just-pastness in

an increasing degree as they fade, and are thus placed in a

series while all sensibly present. It will be context in this

second sense, more specially, that will give us a sense of the

nearness or remoteness of a remembered event.

There is, of course, a difference between knowing the temporal

relation of a remembered event to the present, and knowing the

time-order of two remembered events. Very often our knowledge of

the temporal relation of a remembered event to the present is

inferred from its temporal relations to other remembered events.

It would seem that only rather recent events can be placed at all

accurately by means of feelings giving their temporal relation to

the present, but it is clear that such feelings must play an

essential part in the process of dating remembered events.

We may say, then, that images are regarded by us as more or less

accurate copies of past occurrences because they come to us with

two sorts of feelings: (1) Those that may be called feelings of

familiarity; (2) those that may be collected together as feelings

giving a sense of pastness. The first lead us to trust our

memories, the second to assign places to them in the time-order.

We have now to analyse the memory-belief, as opposed to the

characteristics of images which lead us to base memory-beliefs

upon them.

If we had retained the "subject" or "act" in knowledge, the whole

problem of memory would have been comparatively simple. We could

then have said that remembering is a direct relation between the

present act or subject and the past occurrence remembered: the

act of remembering is present, though its object is past. But the

rejection of the subject renders some more complicated theory

necessary. Remembering has to be a present occurrence in some way

resembling, or related to, what is remembered. And it is

difficult to find any ground, except a pragmatic one, for

supposing that memory is not sheer delusion, if, as seems to be

the case, there is not, apart from memory, any way of

ascertaining that there really was a past occurrence having the

required relation to our present remembering. What, if we

followed Meinong's terminology, we should call the "object" in

memory, i.e. the past event which we are said to be remembering,

is unpleasantly remote from the "content," i.e. the present

mental occurrence in remembering. There is an awkward gulf

between the two, which raises difficulties for the theory of

knowledge. But we must not falsify observation to avoid

theoretical difficulties. For the present, therefore, let us

forget these problems, and try to discover what actually occurs

in memory.

Some points may be taken as fixed, and such as any theory of

memory must arrive at. In this case, as in most others, what may

be taken as certain in advance is rather vague. The study of any

topic is like the continued observation of an object which is

approaching us along a road: what is certain to begin with is the

quite vague knowledge that there is SOME object on the road. If

you attempt to be less vague, and to assert that the object is an

elephant, or a man, or a mad dog, you run a risk of error; but

the purpose of continued observation is to enable you to arrive

at such more precise knowledge. In like manner, in the study of

memory, the certainties with which you begin are very vague, and

the more precise propositions at which you try to arrive are less

certain than the hazy data from which you set out. Nevertheless,

in spite of the risk of error, precision is the goal at which we

must aim.

The first of our vague but indubitable data is that there is

knowledge of the past. We do not yet know with any precision what

we mean by "knowledge," and we must admit that in any given

instance our memory may be at fault. Nevertheless, whatever a

sceptic might urge in theory, we cannot practically doubt that we

got up this morning, that we did various things yesterday, that a

great war has been taking place, and so on. How far our knowledge

of the past is due to memory, and how far to other sources, is of

course a matter to be investigated, but there can be no doubt

that memory forms an indispensable part of our knowledge of the


The second datum is that we certainly have more capacity for

knowing the past than for knowing the future. We know some things

about the future, for example what eclipses there will be; but

this knowledge is a matter of elaborate calculation and

inference, whereas some of our knowledge of the past comes to us

without effort, in the same sort of immediate way in which we

acquire knowledge of occurrences in our present environment. We

might provisionally, though perhaps not quite correctly, define

"memory" as that way of knowing about the past which has no

analogue in our knowledge of the future; such a definition would

at least serve to mark the problem with which we are concerned,

though some expectations may deserve to rank with memory as

regards immediacy.

A third point, perhaps not quite so certain as our previous two,

is that the truth of memory cannot be wholly practical, as

pragmatists wish all truth to be. It seems clear that some of the

things I remember are trivial and without any visible importance

for the future, but that my memory is true (or false) in virtue

of a past event, not in virtue of any future consequences of my

belief. The definition of truth as the correspondence between

beliefs and facts seems peculiarly evident in the case of memory,

as against not only the pragmatist definition but also the

idealist definition by means of coherence. These considerations,

however, are taking us away from psychology, to which we must now


It is important not to confuse the two forms of memory which

Bergson distinguishes in the second chapter of his "Matter and

Memory," namely the sort that consists of habit, and the sort

that consists of independent recollection. He gives the instance

of learning a lesson by heart: when I know it by heart I am said

to "remember" it, but this merely means that I have acquired

certain habits; on the other hand, my recollection of (say) the

second time I read the lesson while I was learning it is the

recollection of a unique event, which occurred only once. The

recollection of a unique event cannot, so Bergson contends, be

wholly constituted by habit, and is in fact something radically

different from the memory which is habit. The recollection alone

is true memory. This distinction is vital to the understanding of

memory. But it is not so easy to carry out in practice as it is

to draw in theory. Habit is a very intrusive feature of our

mental life, and is often present where at first sight it seems

not to be. There is, for example, a habit of remembering a unique

event. When we have once described the event, the words we have

used easily become habitual. We may even have used words to

describe it to ourselves while it was happening; in that case,

the habit of these words may fulfil the function of Bergson's

true memory, while in reality it is nothing but habit-memory. A

gramophone, by the help of suitable records, might relate to us

the incidents of its past; and people are not so different from

gramophones as they like to believe.

In spite, however, of a difficulty in distinguishing the two

forms of memory in practice, there can be no doubt that both

forms exist. I can set to work now to remember things I never

remembered before, such as what I had to eat for breakfast this

morning, and it can hardly be wholly habit that enables me to do

this. It is this sort of occurrence that constitutes the essence

of memory Until we have analysed what happens in such a case as

this, we have not succeeded in understanding memory.

The sort of memory with which we are here concerned is the sort

which is a form of knowledge. Whether knowledge itself is

reducible to habit is a question to which I shall return in a

later lecture; for the present I am only anxious to point out

that, whatever the true analysis of knowledge may be, knowledge

of past occurrences is not proved by behaviour which is due to

past experience. The fact that a man can recite a poem does not

show that he remembers any previous occasion on which he has

recited or read it. Similarly, the performances of animals in

getting out of cages or mazes to which they are accustomed do not

prove that they remember having been in the same situation

before. Arguments in favour of (for example) memory in plants are

only arguments in favour of habit-memory, not of knowledge-

memory. Samuel Butler's arguments in favour of the view that an

animal remembers something of the lives of its ancestors* are,

when examined, only arguments in favour of habit-memory. Semon's

two books, mentioned in an earlier lecture, do not touch

knowledge-memory at all closely. They give laws according to

which images of past occurrences come into our minds, but do not

discuss our belief that these images refer to past occurrences,

which is what constitutes knowledge-memory. It is this that is of

interest to theory of knowledge. I shall speak of it as "true"

memory, to distinguish it from mere habit acquired through past

experience. Before considering true memory, it will be well to

consider two things which are on the way towards memory, namely

the feeling of familiarity and recognition.

* See his "Life and Habit and Unconscious Memory."

We often feel that something in our sensible environment is

familiar, without having any definite recollection of previous

occasions on which we have seen it. We have this feeling normally

in places where we have often been before--at home, or in

well-known streets. Most people and animals find it essential to

their happiness to spend a good deal of their time in familiar

surroundings, which are especially comforting when any danger

threatens. The feeling of familiarity has all sorts of degrees,

down to the stage where we dimly feel that we have seen a person

before. It is by no means always reliable; almost everybody has

at some time experienced the well-known illusion that all that is

happening now happened before at some time. There are occasions

when familiarity does not attach itself to any definite object,

when there is merely a vague feeling that SOMETHING is familiar.

This is illustrated by Turgenev's "Smoke," where the hero is long

puzzled by a haunting sense that something in his present is

recalling something in his past, and at last traces it to the

smell of heliotrope. Whenever the sense of familiarity occurs

without a definite object, it leads us to search the environment

until we are satisfied that we have found the appropriate object,

which leads us to the judgment: "THIS is familiar." I think we

may regard familiarity as a definite feeling, capable of existing

without an object, but normally standing in a specific relation

to some feature of the environment, the relation being that which

we express in words by saying that the feature in question is

familiar. The judgment that what is familiar has been experienced

before is a product of reflection, and is no part of the feeling

of familiarity, such as a horse may be supposed to have when he

returns to his stable. Thus no knowledge as to the past is to be

derived from the feeling of familiarity alone.

A further stage is RECOGNITION. This may be taken in two senses,

the first when a thing not merely feels familiar, but we know it

is such-and-such. We recognize our friend Jones, we know cats and

dogs when we see them, and so on. Here we have a definite

influence of past experience, but not necessarily any actual

knowledge of the past. When we see a cat, we know it is a cat

because of previous cats we have seen, but we do not, as a rule,

recollect at the moment any particular occasion when we have seen

a cat. Recognition in this sense does not necessarily involve

more than a habit of association: the kind of object we are

seeing at the moment is associated with the word "cat," or with

an auditory image of purring, or whatever other characteristic we

may happen to recognize in. the cat of the moment. We are, of

course, in fact able to judge, when we recognize an object, that

we have seen it before, but this judgment is something over and

above recognition in this first sense, and may very probably be

impossible to animals that nevertheless have the experience of

recognition in this first sense of the word.

There is, however, another sense of the word, in which we mean by

recognition, not knowing the name of a thing or some other

property of it, but knowing that we have seen it before In this

sense recognition does involve knowledge about the Fast. This

knowledge is memory in one sense, though in another it is not. It

does not involve a definite memory of a definite past event, but

only the knowledge that something happening now is similar to

something that happened before. It differs from the sense of

familiarity by being cognitive; it is a belief or judgment, which

the sense of familiarity is not. I do not wish to undertake the

analysis of belief at present, since it will be the subject of

the twelfth lecture; for the present I merely wish to emphasize

the fact that recognition, in our second sense, consists in a

belief, which we may express approximately in the words: "This

has existed before."

There are, however, several points in which such an account of

recognition is inadequate. To begin with, it might seem at first

sight more correct to define recognition as "I have seen this

before" than as "this has existed before." We recognize a thing

(it may be urged) as having been in our experience before,

whatever that may mean; we do not recognize it as merely having

been in the world before. I am not sure that there is anything

substantial in this point. The definition of "my experience" is

difficult; broadly speaking, it is everything that is connected

with what I am experiencing now by certain links, of which the

various forms of memory are among the most important. Thus, if I

recognize a thing, the occasion of its previous existence in

virtue of which I recognize it forms part of "my experience" by

DEFINITION: recognition will be one of the marks by which my

experience is singled out from the rest of the world. Of course,

the words "this has existed before" are a very inadequate

translation of what actually happens when we form a judgment of

recognition, but that is unavoidable: words are framed to express

a level of thought which is by no means primitive, and are quite

incapable of expressing such an elementary occurrence as

recognition. I shall return to what is virtually the same

question in connection with true memory, which raises exactly

similar problems.

A second point is that, when we recognize something, it was not

in fact the very same thing, but only something similar, that we

experienced on a former occasion. Suppose the object in question

is a friend's face. A person's face is always changing, and is

not exactly the same on any two occasions. Common sense treats it

as one face with varying expressions; but the varying expressions

actually exist, each at its proper time, while the one face is

merely a logical construction. We regard two objects as the same,

for common-sense purposes, when the reaction they call for is

practically the same. Two visual appearances, to both of which it

is appropriate to say: "Hullo, Jones!" are treated as appearances

of one identical object, namely Jones. The name "Jones" is

applicable to both, and it is only reflection that shows us that

many diverse particulars are collected together to form the

meaning of the name "Jones." What we see on any one occasion is

not the whole series of particulars that make up Jones, but only

one of them (or a few in quick succession). On another occasion

we see another member of the series, but it is sufficiently

similar to count as the same from the standpoint of common sense.

Accordingly, when we judge "I have seen THIS before," we judge

falsely if "this" is taken as applying to the actual constituent

of the world that we are seeing at the moment. The word "this"

must be interpreted vaguely so as to include anything

sufficiently like what we are seeing at the moment. Here, again,

we shall find a similar point as regards true memory; and in

connection with true memory we will consider the point again. It

is sometimes suggested, by those who favour behaviourist views,

that recognition consists in behaving in the same way when a

stimulus is repeated as we behaved on the first occasion when it

occurred. This seems to be the exact opposite of the truth. The

essence of recognition is in the DIFFERENCE between a repeated

stimulus and a new one. On the first occasion there is no

recognition; on the second occasion there is. In fact,

recognition is another instance of the peculiarity of causal laws

in psychology, namely, that the causal unit is not a single

event, but two or more events Habit is the great instance of

this, but recognition is another. A stimulus occurring once has a

certain effect; occurring twice, it has the further effect of

recognition. Thus the phenomenon of recognition has as its cause

the two occasions when the stimulus has occurred; either alone is

insufficient. This complexity of causes in psychology might be

connected with Bergson's arguments against repetition in the

mental world. It does not prove that there are no causal laws in

psychology, as Bergson suggests; but it does prove that the

causal laws of psychology are Prima facie very different from

those of physics. On the possibility of explaining away the

difference as due to the peculiarities of nervous tissue I have

spoken before, but this possibility must not be forgotten if we

are tempted to draw unwarranted metaphysical deductions.

True memory, which we must now endeavour to understand, consists

of knowledge of past events, but not of all such knowledge. Some

knowledge of past events, for example what we learn through

reading history, is on a par with the knowledge we can acquire

concerning the future: it is obtained by inference, not (so to

speak) spontaneously. There is a similar distinction in our

knowledge of the present: some of it is obtained through the

senses, some in more indirect ways. I know that there are at this

moment a number of people in the streets of New York, but I do

not know this in the immediate way in which I know of the people

whom I see by looking out of my window. It is not easy to state

precisely wherein the difference between these two sorts of

knowledge consists, but it is easy to feel the difference. For

the moment, I shall not stop to analyse it, but shall content

myself with saying that, in this respect, memory resembles the

knowledge derived from the senses. It is immediate, not inferred,

not abstract; it differs from perception mainly by being referred

to the past.

In regard to memory, as throughout the analysis of knowledge,

there are two very distinct problems, namely (1) as to the nature

of the present occurrence in knowing; (2) as to the relation of

this occurrence to what is known. When we remember, the knowing

is now, while what is known is in the past. Our two questions

are, in the case of memory

(1) What is the present occurrence when we remember?

(2) What is the relation of this present occurrence to the past

event which is remembered?

Of these two questions, only the first concerns the psychologist;

the second belongs to theory of knowledge. At the same time, if

we accept the vague datum with which we began, to the effect

that, in some sense, there is knowledge of the past, we shall

have to find, if we can, such an account of the present

occurrence in remembering as will make it not impossible for

remembering to give us knowledge of the past. For the present,

however, we shall do well to forget the problems concerning

theory of knowledge, and concentrate upon the purely

psychological problem of memory.

Between memory-image and sensation there is an intermediate

experience concerning the immediate past. For example, a sound

that we have just heard is present to us in a way which differs

both from the sensation while we are hearing the sound and from

the memory-image of something heard days or weeks ago. James

states that it is this way of apprehending the immediate past

that is "the ORIGINAL of our experience of pastness, from whence

we get the meaning of the term"("Psychology," i, p. 604).

Everyone knows the experience of noticing (say) that the clock

HAS BEEN striking, when we did not notice it while it was

striking. And when we hear a remark spoken, we are conscious of

the earlier words while the later ones are being uttered, and

this retention feels different from recollection of something

definitely past. A sensation fades gradually, passing by

continuous gradations to the status of an image. This retention

of the immediate past in a condition intermediate between

sensation and image may be called "immediate memory." Everything

belonging to it is included with sensation in what is called the

"specious present." The specious present includes elements at all

stages on the journey from sensation to image. It is this fact

that enables us to apprehend such things as movements, or the

order of the words in a spoken sentence. Succession can occur

within the specious present, of which we can distinguish some

parts as earlier and others as later. It is to be supposed that

the earliest parts are those that have faded most from their

original force, while the latest parts are those that retain

their full sensational character. At the beginning of a stimulus

we have a sensation; then a gradual transition; and at the end an

image. Sensations while they are fading are called "akoluthic"

sensations.* When the process of fading is completed (which

happens very quickly), we arrive at the image, which is capable

of being revived on subsequent occasions with very little change.

True memory, as opposed to "immediate memory," applies only to

events sufficiently distant to have come to an end of the period

of fading. Such events, if they are represented by anything

present, can only be represented by images, not by those

intermediate stages, between sensations and images, which occur

during the period of fading.

* See Semon, "Die mnemischen Empfindungen," chap. vi.

Immediate memory is important both because it provides experience

of succession, and because it bridges the gulf between sensations

and the images which are their copies. But it is now time to

resume the consideration of true memory.

Suppose you ask me what I ate for breakfast this morning.

Suppose, further, that I have not thought about my breakfast in

the meantime, and that I did not, while I was eating it, put into

words what it consisted of. In this case my recollection will be

true memory, not habit-memory. The process of remembering will

consist of calling up images of my breakfast, which will come to

me with a feeling of belief such as distinguishes memory-images

from mere imagination-images. Or sometimes words may come without

the intermediary of images; but in this case equally the feeling

of belief is essential.

Let us omit from our consideration, for the present, the memories

in which words replace images. These are always, I think, really

habit-memories, the memories that use images being the typical

true memories.

Memory-images and imagination-images do not differ in their

intrinsic qualities, so far as we can discover. They differ by

the fact that the images that constitute memories, unlike those

that constitute imagination, are accompanied by a feeling of

belief which may be expressed in the words "this happened." The

mere occurrence of images, without this feeling of belief,

constitutes imagination; it is the element of belief that is the

distinctive thing in memory.*

* For belief of a specific kind, cf. Dorothy Wrinch "On the

Nature of Memory," "Mind," January, 1920.

There are, if I am not mistaken, at least three different kinds

of belief-feeling, which we may call respectively memory,

expectation and bare assent. In what I call bare assent, there is

no time-element in the feeling of belief, though there may be in

the content of what is believed. If I believe that Caesar landed

in Britain in B.C. 55, the time-determination lies, not in the

feeling of belief, but in what is believed. I do not remember the

occurrence, but have the same feeling towards it as towards the

announcement of an eclipse next year. But when I have seen a

flash of lightning and am waiting for the thunder, I have a

belief-feeling analogous to memory, except that it refers to the

future: I have an image of thunder, combined with a feeling which

may be expressed in the words: "this will happen." So, in memory,

the pastness lies, not in the content of what is believed, but in

the nature of the belief-feeling. I might have just the same

images and expect their realization; I might entertain them

without any belief, as in reading a novel; or I might entertain

them together with a time-determination, and give bare assent, as

in reading history. I shall return to this subject in a later

lecture, when we come to the analysis of belief. For the present,

I wish to make it clear that a certain special kind of belief is

the distinctive characteristic of memory.

The problem as to whether memory can be explained as habit or

association requires to be considered afresh in connection with

the causes of our remembering something. Let us take again the

case of my being asked what I had for breakfast this morning. In

this case the question leads to my setting to work to recollect.

It is a little strange that the question should instruct me as to

what it is that I am to recall. This has to do with understanding

words, which will be the topic of the next lecture; but something

must be said about it now. Our understanding of the words

"breakfast this morning" is a habit, in spite of the fact that on

each fresh day they point to a different occasion. "This morning"

does not, whenever it is used, mean the same thing, as "John" or

"St. Paul's" does; it means a different period of time on each

different day. It follows that the habit which constitutes our

understanding of the words "this morning" is not the habit of

associating the words with a fixed object, but the habit of

associating them with something having a fixed time-relation to

our present. This morning has, to-day, the same time-relation to

my present that yesterday morning had yesterday. In order to

understand the phrase "this morning" it is necessary that we

should have a way of feeling time-intervals, and that this

feeling should give what is constant in the meaning of the words

"this morning." This appreciation of time-intervals is, however,

obviously a product of memory, not a presupposition of it. It

will be better, therefore, if we wish to analyse the causation of

memory by something not presupposing memory, to take some other

instance than that of a question about "this morning."

Let us take the case of coming into a familiar room where

something has been changed--say a new picture hung on the wall.

We may at first have only a sense that SOMETHING is unfamiliar,

but presently we shall remember, and say "that picture was not on

the wall before." In order to make the case definite, we will

suppose that we were only in the room on one former occasion. In

this case it seems fairly clear what happens. The other objects

in the room are associated, through the former occasion, with a

blank space of wall where now there is a picture. They call up an

image of a blank wall, which clashes with perception of the

picture. The image is associated with the belief-feeling which we

found to be distinctive of memory, since it can neither be

abolished nor harmonized with perception. If the room had

remained unchanged, we might have had only the feeling of

familiarity without the definite remembering; it is the change

that drives us from the present to memory of the past.

We may generalize this instance so as to cover the causes of many

memories. Some present feature of the environment is associated,

through past experiences, with something now absent; this absent

something comes before us as an image, and is contrasted with

present sensation. In cases of this sort, habit (or association)

explains why the present feature of the environment brings up the

memory-image, but it does not explain the memory-belief. Perhaps

a more complete analysis could explain the memory-belief also on

lines of association and habit, but the causes of beliefs are

obscure, and we cannot investigate them yet. For the present we

must content ourselves with the fact that the memory-image can be

explained by habit. As regards the memory-belief, we must, at

least provisionally, accept Bergson's view that it cannot be

brought under the head of habit, at any rate when it first

occurs, i.e. when we remember something we never remembered


We must now consider somewhat more closely the content of a

memory-belief. The memory-belief confers upon the memory-image

something which we may call "meaning;" it makes us feel that the

image points to an object which existed in the past. In order to

deal with this topic we must consider the verbal expression of

the memory-belief. We might be tempted to put the memory-belief

into the words: "Something like this image occurred." But such

words would be very far from an accurate translation of the

simplest kind of memory-belief. "Something like this image" is a

very complicated conception. In the simplest kind of memory we

are not aware of the difference between an image and the

sensation which it copies, which may be called its "prototype."

When the image is before us, we judge rather "this occurred." The

image is not distinguished from the object which existed in the

past: the word "this" covers both, and enables us to have a

memory-belief which does not introduce the complicated notion

"something like this."

It might be objected that, if we judge "this occurred" when in

fact "this" is a present image, we judge falsely, and the

memory-belief, so interpreted, becomes deceptive. This, however,

would be a mistake, produced by attempting to give to words a

precision which they do not possess when used by unsophisticated

people. It is true that the image is not absolutely identical

with its prototype, and if the word "this" meant the image to the

exclusion of everything else, the judgment "this occurred" would

be false. But identity is a precise conception, and no word, in

ordinary speech, stands for anything precise. Ordinary speech

does not distinguish between identity and close similarity. A

word always applies, not only to one particular, but to a group

of associated particulars, which are not recognized as multiple

in common thought or speech. Thus primitive memory, when it

judges that "this occurred," is vague, but not false.

Vague identity, which is really close similarity, has been a

source of many of the confusions by which philosophy has lived.

Of a vague subject, such as a "this," which is both an image and

its prototype, contradictory predicates are true simultaneously:

this existed and does not exist, since it is a thing remembered,

but also this exists and did not exist, since it is a present

image. Hence Bergson's interpenetration of the present by the

past, Hegelian continuity and identity-in-diversity, and a host

of other notions which are thought to be profound because they

are obscure and confused. The contradictions resulting from

confounding image and prototype in memory force us to precision.

But when we become precise, our remembering becomes different

from that of ordinary life, and if we forget this we shall go

wrong in the analysis of ordinary memory.

Vagueness and accuracy are important notions, which it is very

necessary to understand. Both are a matter of degree. All

thinking is vague to some extent, and complete accuracy is a

theoretical ideal not practically attainable. To understand what

is meant by accuracy, it will be well to consider first

instruments of measurement, such as a balance or a thermometer.

These are said to be accurate when they give different results

for very slightly different stimuli.* A clinical thermometer is

accurate when it enables us to detect very slight differences in

the temperature of the blood. We may say generally that an

instrument is accurate in proportion as it reacts differently to

very slightly different stimuli. When a small difference of

stimulus produces a great difference of reaction, the instrument

is accurate; in the contrary case it is not.

* This is a necessary but not a sufficient condition. The subject

of accuracy and vagueness will be considered again in Lecture


Exactly the same thing applies in defining accuracy of thought or

perception. A musician will respond differently to very minute

differences in playing which would be quite imperceptible to the

ordinary mortal. A negro can see the difference between one negro

and another one is his friend, another his enemy. But to us such

different responses are impossible: we can merely apply the word

"negro" indiscriminately. Accuracy of response in regard to any

particular kind of stimulus is improved by practice.

Understanding a language is a case in point. Few Frenchmen can

hear any difference between the sounds "hall" and "hole," which

produce quite different impressions upon us. The two statements

"the hall is full of water" and "the hole is full of water" call

for different responses, and a hearing which cannot distinguish

between them is inaccurate or vague in this respect.

Precision and vagueness in thought, as in perception, depend upon

the degree of difference between responses to more or less

similar stimuli. In the case of thought, the response does not

follow immediately upon the sensational stimulus, but that makes

no difference as regards our present question. Thus to revert to

memory: A memory is "vague" when it is appropriate to many

different occurrences: for instance, "I met a man" is vague,

since any man would verify it. A memory is "precise" when the

occurrences that would verify it are narrowly circumscribed: for

instance, "I met Jones" is precise as compared to "I met a man."

A memory is "accurate" when it is both precise and true, i.e. in

the above instance, if it was Jones I met. It is precise even if

it is false, provided some very definite occurrence would have

been required to make it true.

It follows from what has been said that a vague thought has more

likelihood of being true than a precise one. To try and hit an

object with a vague thought is like trying to hit the bull's eye

with a lump of putty: when the putty reaches the target, it

flattens out all over it, and probably covers the bull's eye

along with the rest. To try and hit an object with a precise

thought is like trying to hit the bull's eye with a bullet. The

advantage of the precise thought is that it distinguishes between

the bull's eye and the rest of the target. For example, if the

whole target is represented by the fungus family and the bull's

eye by mushrooms, a vague thought which can only hit the target

as a whole is not much use from a culinary point of view. And

when I merely remember that I met a man, my memory may be very

inadequate to my practical requirements, since it may make a

great difference whether I met Brown or Jones. The memory "I met

Jones" is relatively precise. It is accurate if I met Jones,

inaccurate if I met Brown, but precise in either case as against

the mere recollection that I met a man.

The distinction between accuracy and precision is however, not

fundamental. We may omit precision from out thoughts and confine

ourselves to the distinction between accuracy and vagueness. We

may then set up the following definitions:

An instrument is "reliable" with respect to a given set of

stimuli when to stimuli which are not relevantly different it

gives always responses which are not relevantly different.

An instrument is a "measure" of a set of stimuli which are

serially ordered when its responses, in all cases where they are

relevantly different, are arranged in a series in the same order.

The "degree of accuracy" of an instrument which is a reliable

measurer is the ratio of the difference of response to the

difference of stimulus in cases where the difference of stimulus

is small.* That is to say, if a small difference of stimulus

produces a great difference of response, the instrument is very

accurate; in the contrary case, very inaccurate.

* Strictly speaking, the limit of this, i.e. the derivative of

the response with respect to the stimulus.

A mental response is called "vague" in proportion to its lack of

accuracy, or rather precision.

These definitions will be found useful, not only in the case of

memory, but in almost all questions concerned with knowledge.

It should be observed that vague beliefs, so far from being

necessarily false, have a better chance of truth than precise

ones, though their truth is less valuable than that of precise

beliefs, since they do not distinguish between occurrences which

may differ in important ways.

The whole of the above discussion of vagueness and accuracy was

occasioned by the attempt to interpret the word "this" when we

judge in verbal memory that "this occurred." The word "this," in

such a judgment, is a vague word, equally applicable to the

present memory-image and to the past occurrence which is its

prototype. A vague word is not to be identified with a general

word, though in practice the distinction may often be blurred. A

word is general when it is understood to be applicable to a

number of different objects in virtue of some common property. A

word is vague when it is in fact applicable to a number of

different objects because, in virtue of some common property,

they have not appeared, to the person using the word, to be

distinct. I emphatically do not mean that he has judged them to

be identical, but merely that he has made the same response to

them all and has not judged them to be different. We may compare

a vague word to a jelly and a general word to a heap of shot.

Vague words precede judgments of identity and difference; both

general and particular words are subsequent to such judgments.

The word "this" in the primitive memory-belief is a vague word,

not a general word; it covers both the image and its prototype

because the two are not distinguished.*

* On the vague and the general cf. Ribot: "Evolution of General

Ideas," Open Court Co., 1899, p. 32: "The sole permissible

formula is this: Intelligence progresses from the indefinite to

the definite. If 'indefinite' is taken as synonymous with

general, it may be said that the particular does not appear at

the outset, but neither does the general in any exact sense: the

vague would be more appropriate. In other words, no sooner has

the intellect progressed beyond the moment of perception and of

its immediate reproduction in memory, than the generic image

makes its appearance, i.e. a state intermediate between the

particular and the general, participating in the nature of the

one and of the other--a confused simplification."

But we have not yet finished our analysis of the memory-belief.

The tense in the belief that "this occurred" is provided by the

nature of the belief-feeling involved in memory; the word "this,"

as we have seen, has a vagueness which we have tried to describe.

But we must still ask what we mean by "occurred." The image is,

in one sense, occurring now; and therefore we must find some

other sense in which the past event occurred but the image does

not occur.

There are two distinct questions to be asked: (1) What causes us

to say that a thing occurs? (2) What are we feeling when we say

this? As to the first question, in the crude use of the word,

which is what concerns us, memory-images would not be said to

occur; they would not be noticed in themselves, but merely used

as signs of the past event. Images are "merely imaginary"; they

have not, in crude thought, the sort of reality that belongs to

outside bodies. Roughly speaking, "real" things would be those

that can cause sensations, those that have correlations of the

sort that constitute physical objects. A thing is said to be

"real" or to "occur" when it fits into a context of such

correlations. The prototype of our memory-image did fit into a

physical context, while our memory-image does not. This causes us

to feel that the prototype was "real," while the image is


But the answer to our second question, namely as to what we are

feeling when we say a thing "occurs" or is "real," must be

somewhat different. We do not, unless we are unusually

reflective, think about the presence or absence of correlations:

we merely have different feelings which, intellectualized, may be

represented as expectations of the presence or absence of

correlations. A thing which "feels real" inspires us with hopes

or fears, expectations or curiosities, which are wholly absent

when a thing "feels imaginary." The feeling of reality is a

feeling akin to respect: it belongs PRIMARILY to whatever can do

things to us without our voluntary co-operation. This feeling of

reality, related to the memory-image, and referred to the past by

the specific kind of belief-feeling that is characteristic of

memory, seems to be what constitutes the act of remembering in

its pure form.

We may now summarize our analysis of pure memory.

Memory demands (a) an image, (b) a belief in past existence. The

belief may be expressed in the words "this existed."

The belief, like every other, may be analysed into (1) the

believing, (2) what is believed. The believing is a specific

feeling or sensation or complex of sensations, different from

expectation or bare assent in a way that makes the belief refer

to the past; the reference to the past lies in the

belief-feeling, not in the content believed. There is a relation

between the belief-feeling and the content, making the

belief-feeling refer to the content, and expressed by saying that

the content is what is believed.

The content believed may or may not be expressed in words. Let us

take first the case when it is not. In that case, if we are

merely remembering that something of which we now have an image

occurred, the content consists of (a) the image, (b) the feeling,

analogous to respect, which we translate by saying that something

is "real" as opposed to "imaginary," (c) a relation between the

image and the feeling of reality, of the sort expressed when we

say that the feeling refers to the image. This content does not

contain in itself any time-determination

the time-determination lies in the nature of the belief feeling,

which is that called "remembering" or (better) "recollecting." It

is only subsequent reflection upon this reference to the past

that makes us realize the distinction between the image and the

event recollected. When we have made this distinction, we can say

that the image "means" the past event.

The content expressed in words is best represented by the words

"the existence of this," since these words do not involve tense,

which belongs to the belief-feeling, not to the content. Here

"this" is a vague term, covering the memory-image and anything

very like it, including its prototype. "Existence" expresses the

feeling of a "reality" aroused primarily by whatever can have

effects upon us without our voluntary co-operation. The word "of"

in the phrase "the existence of this" represents the relation

which subsists between the feeling of reality and the "this."

This analysis of memory is probably extremely faulty, but I do

not know how to improve it.

NOTE.-When I speak of a FEELING of belief, I use the word

"feeling" in a popular sense, to cover a sensation or an image or

a complex of sensations or images or both; I use this word

because I do not wish to commit myself to any special analysis of

the belief-feeling.


The problem with which we shall be concerned in this lecture is

the problem of determining what is the relation called "meaning."

The word "Napoleon," we say, "means" a certain person. In saying

this, we are asserting a relation between the word "Napoleon" and

the person so designated. It is this relation that we must now


Let us first consider what sort of object a word is when

considered simply as a physical thing, apart from its meaning. To

begin with, there are many instances of a word, namely all the

different occasions when it is employed. Thus a word is not

something unique and particular, but a set of occurrences. If we

confine ourselves to spoken words, a word has two aspects,

according as we regard it from the point of view of the speaker

or from that of the hearer. From the point of view of the

speaker, a single instance of the use of a word consists of a

certain set of movements in the throat and mouth, combined with

breath. From the point of view of the hearer, a single instance

of the use of a word consists of a certain series of sounds, each

being approximately represented by a single letter in writing,

though in practice a letter may represent several sounds, or

several letters may represent one sound. The connection between

the spoken word and the word as it reaches the hearer is causal.

Let us confine ourselves to the spoken word, which is the more

important for the analysis of what is called "thought." Then we

may say that a single instance of the spoken word consists of a

series of movements, and the word consists of a whole set of such

series, each member of the set being very similar to each other

member. That is to say, any two instances of the word "Napoleon"

are very similar, and each instance consists of a series of

movements in the mouth.

A single word, accordingly, is by no means simple it is a class

of similar series of movements (confining ourselves still to the

spoken word). The degree of similarity required cannot be

precisely defined: a man may pronounce the word "Napoleon" so

badly that it can hardly be determined whether he has really

pronounced it or not. The instances of a word shade off into

other movements by imperceptible degrees. And exactly analogous

observations apply to words heard or written or read. But in what

has been said so far we have not even broached the question of

the DEFINITION of a word, since "meaning" is clearly what

distinguishes a word from other sets of similar movements, and

"meaning" remains to be defined.

It is natural to think of the meaning of a word as something

conventional. This, however, is only true with great limitations.

A new word can be added to an existing language by a mere

convention, as is done, for instance, with new scientific terms.

But the basis of a language is not conventional, either from the

point of view of the individual or from that of the community. A

child learning to speak is learning habits and associations which

are just as much determined by the environment as the habit of

expecting dogs to bark and cocks to crow. The community that

speaks a language has learnt it, and modified it by processes

almost all of which are not deliberate, but the results of causes

operating according to more or less ascertainable laws. If we

trace any Indo-European language back far enough, we arrive

hypothetically (at any rate according to some authorities) at the

stage when language consisted only of the roots out of which

subsequent words have grown. How these roots acquired their

meanings is not known, but a conventional origin is clearly just

as mythical as the social contract by which Hobbes and Rousseau

supposed civil government to have been established. We can hardly

suppose a parliament of hitherto speechless elders meeting

together and agreeing to call a cow a cow and a wolf a wolf. The

association of words with their meanings must have grown up by

some natural process, though at present the nature of the process

is unknown.

Spoken and written words are, of course, not the only way of

conveying meaning. A large part of one of Wundt's two vast

volumes on language in his "Volkerpsychologie" is concerned with

gesture-language. Ants appear to be able to communicate a certain

amount of information by means of their antennae. Probably

writing itself, which we now regard as merely a way of

representing speech, was originally an independent language, as

it has remained to this day in China. Writing seems to have

consisted originally of pictures, which gradually became

conventionalized, coming in time to represent syllables, and

finally letters on the telephone principle of "T for Tommy." But

it would seem that writing nowhere began as an attempt to

represent speech it began as a direct pictorial representation of

what was to be expressed. The essence of language lies, not in

the use of this or that special means of communication, but in

the employment of fixed associations (however these may have

originated) in order that something now sensible--a spoken word,

a picture, a gesture, or what not--may call up the "idea" of

something else. Whenever this is done, what is now sensible may

be called a "sign" or "symbol," and that of which it is intended

to call up the "idea" may be called its "meaning." This is a

rough outline of what constitutes "meaning." But we must fill in

the outline in various ways. And, since we are concerned with

what is called "thought," we must pay more attention than we

otherwise should do to the private as opposed to the social use

of language. Language profoundly affects our thoughts, and it is

this aspect of language that is of most importance to us in our

present inquiry. We are almost more concerned with the internal

speech that is never uttered than we are with the things said out

loud to other people.

When we ask what constitutes meaning, we are not asking what is

the meaning of this or that particular word. The word "Napoleon"

means a certain individual; but we are asking, not who is the

individual meant, but what is the relation of the word to the

individual which makes the one mean the other. But just as it is

useful to realize the nature of a word as part of the physical

world, so it is useful to realize the sort of thing that a word

may mean. When we are clear both as to what a word is in its

physical aspect, and as to what sort of thing it can mean, we are

in a better position to discover the relation of the two which is


The things that words mean differ more than words do. There are

different sorts of words, distinguished by the grammarians; and

there are logical distinctions, which are connected to some

extent, though not so closely as was formerly supposed, with the

grammatical distinctions of parts of speech. It is easy, however,

to be misled by grammar, particularly if all the languages we

know belong to one family. In some languages, according to some

authorities, the distinction of parts of speech does not exist;

in many languages it is widely different from that to which we

are accustomed in the Indo-European languages. These facts have

to be borne in mind if we are to avoid giving metaphysical

importance to mere accidents of our own speech.

In considering what words mean, it is natural to start with

proper names, and we will again take "Napoleon" as our instance.

We commonly imagine, when we use a proper name, that we mean one

definite entity, the particular individual who was called

"Napoleon." But what we know as a person is not simple. There MAY

be a single simple ego which was Napoleon, and remained strictly

identical from his birth to his death. There is no way of proving

that this cannot be the case, but there is also not the slightest

reason to suppose that it is the case. Napoleon as he was

empirically known consisted of a series of gradually changing

appearances: first a squalling baby, then a boy, then a slim and

beautiful youth, then a fat and slothful person very

magnificently dressed This series of appearances, and various

occurrences having certain kinds of causal connections with them,

constitute Napoleon as empirically known, and therefore are

Napoleon in so far as he forms part of the experienced world.

Napoleon is a complicated series of occurrences, bound together

by causal laws, not, like instances of a word, by similarities.

For although a person changes gradually, and presents similar

appearances on two nearly contemporaneous occasions, it is not

these similarities that constitute the person, as appears from

the "Comedy of Errors" for example.

Thus in the case of a proper name, while the word is a set of

similar series of movements, what it means is a series of

occurrences bound together by causal laws of that special kind

that makes the occurrences taken together constitute what we call

one person, or one animal or thing, in case the name applies to

an animal or thing instead of to a person. Neither the word nor

what it names is one of the ultimate indivisible constituents of

the world. In language there is no direct way of designating one

of the ultimate brief existents that go to make up the

collections we call things or persons. If we want to speak of

such existentswhich hardly happens except in philosophy-we have

to do it by means of some elaborate phrase, such as "the visual

sensation which occupied the centre of my field of vision at noon

on January 1, 1919." Such ultimate simples I call "particulars."

Particulars MIGHT have proper names, and no doubt would have if

language had been invented by scientifically trained observers

for purposes of philosophy and logic. But as language was

invented for practical ends, particulars have remained one and

all without a name.

We are not, in practice, much concerned with the actual

particulars that come into our experience in sensation; we are

concerned rather with whole systems to which the particulars

belong and of which they are signs. What we see makes us say

"Hullo, there's Jones," and the fact that what we see is a sign

of Jones (which is the case because it is one of the particulars

that make up Jones) is more interesting to us than the actual

particular itself. Hence we give the name "Jones" to the whole

set of particulars, but do not trouble to give separate names to

the separate particulars that make up the set.

Passing on from proper names, we come next to general names, such

as "man," "cat," "triangle." A word such as "man" means a whole

class of such collections of particulars as have proper names.

The several members of the class are assembled together in virtue

of some similarity or common property. All men resemble each

other in certain important respects; hence we want a word which

shall be equally applicable to all of them. We only give proper

names to the individuals of a species when they differ inter se

in practically important respects. In other cases we do not do

this. A poker, for instance, is just a poker; we do not call one

"John" and another "Peter."

There is a large class of words, such as "eating," "walking,"

"speaking," which mean a set of similar occurrences. Two

instances of walking have the same name because they resemble

each other, whereas two instances of Jones have the same name

because they are causally connected. In practice, however, it is

difficult to make any precise distinction between a word such as

"walking" and a general name such as "man." One instance of

walking cannot be concentrated into an instant: it is a process

in time, in which there is a causal connection between the

earlier and later parts, as between the earlier and later parts

of Jones. Thus an instance of walking differs from an instance of

man solely by the fact that it has a shorter life. There is a

notion that an instance of walking, as compared with Jones, is

unsubstantial, but this seems to be a mistake. We think that

Jones walks, and that there could not be any walking unless there

were somebody like Jones to perform the walking. But it is

equally true that there could be no Jones unless there were

something like walking for him to do. The notion that actions are

performed by an agent is liable to the same kind of criticism as

the notion that thinking needs a subject or ego, which we

rejected in Lecture I. To say that it is Jones who is walking is

merely to say that the walking in question is part of the whole

series of occurrences which is Jones. There is no LOGICAL

impossibility in walking occurring as an isolated phenomenon, not

forming part of any such series as we call a "person."

We may therefore class with "eating," "walking," "speaking" words

such as "rain," "sunrise," "lightning," which do not denote what

would commonly be called actions. These words illustrate,

incidentally, how little we can trust to the grammatical

distinction of parts of speech, since the substantive "rain" and

the verb "to rain" denote precisely the same class of

meteorological occurrences. The distinction between the class of

objects denoted by such a word and the class of objects denoted

by a general name such as "man," "vegetable," or "planet," is

that the sort of object which is an instance of (say) "lightning"

is much simpler than (say) an individual man. (I am speaking of

lightning as a sensible phenomenon, not as it is described in

physics.) The distinction is one of degree, not of kind. But

there is, from the point of view of ordinary thought, a great

difference between a process which, like a flash of lightning,

can be wholly comprised within one specious present and a process

which, like the life of a man, has to be pieced together by

observation and memory and the apprehension of causal

connections. We may say broadly, therefore, that a word of the

kind we have been discussing denotes a set of similar

occurrences, each (as a rule) much more brief and less complex

than a person or thing. Words themselves, as we have seen, are

sets of similar occurrences of this kind. Thus there is more

logical affinity between a word and what it means in the case of

words of our present sort than in any other case.

There is no very great difference between such words as we have

just been considering and words denoting qualities, such as

"white" or "round." The chief difference is that words of this

latter sort do not denote processes, however brief, but static

features of the world. Snow falls, and is white; the falling is a

process, the whiteness is not. Whether there is a universal,

called "whiteness," or whether white things are to be defined as

those having a certain kind of similarity to a standard thing,

say freshly fallen snow, is a question which need not concern us,

and which I believe to be strictly insoluble. For our purposes,

we may take the word "white" as denoting a certain set of similar

particulars or collections of particulars, the similarity being

in respect of a static quality, not of a process.

From the logical point of view, a very important class of words

are those that express relations, such as "in," "above,"

"before," "greater," and so on. The meaning of one of these words

differs very fundamentally from the meaning of one of any of our

previous classes, being more abstract and logically simpler than

any of them. If our business were logic, we should have to spend

much time on these words. But as it is psychology that concerns

us, we will merely note their special character and pass on,

since the logical classification of words is not our main


We will consider next the question what is implied by saying that

a person "understands" a word, in the sense in which one

understands a word in one's own language, but not in a language

of which one is ignorant. We may say that a person understands a

word when (a) suitable circumstances make him use it, (b) the

hearing of it causes suitable behaviour in him. We may call these

two active and passive understanding respectively. Dogs often

have passive understanding of some words, but not active

understanding, since they cannot use words.

It is not necessary, in order that a man should "understand" a

word, that he should "know what it means," in the sense of being

able to say "this word means so-and-so." Understanding words does

not consist in knowing their dictionary definitions, or in being

able to specify the objects to which they are appropriate. Such

understanding as this may belong to lexicographers and students,

but not to ordinary mortals in ordinary life. Understanding

language is more like understanding cricket*: it is a matter of

habits, acquired in oneself and rightly presumed in others. To

say that a word has a meaning is not to say that those who use

the word correctly have ever thought out what the meaning is: the

use of the word comes first, and the meaning is to be distilled

out of it by observation and analysis. Moreover, the meaning of a

word is not absolutely definite: there is always a greater or

less degree of vagueness. The meaning is an area, like a target:

it may have a bull's eye, but the outlying parts of the target

are still more or less within the meaning, in a gradually

diminishing degree as we travel further from the bull's eye. As

language grows more precise, there is less and less of the target

outside the bull's eye, and the bull's eye itself grows smaller

and smaller; but the bull's eye never shrinks to a point, and

there is always a doubtful region, however small, surrounding


* This point of view, extended to the analysis of "thought" is

urged with great force by J. B. Watson, both in his "Behavior,"

and in "Psychology from the Standpoint of a Behaviorist"

(Lippincott. 1919), chap. ix.

** On the understanding of words, a very admirable little book is

Ribot's "Evolution of General Ideas," Open Court Co., 1899. Ribot

says (p. 131): "We learn to understand a concept as we learn to

walk, dance, fence or play a musical instrument: it is a habit,

i.e. an organized memory. General terms cover an organized,

latent knowledge which is the hidden capital without which we

should be in a state of bankruptcy, manipulating false money or

paper of no value. General ideas are habits in the intellectual


A word is used "correctly" when the average hearer will be

affected by it in the way intended. This is a psychological, not

a literary, definition of "correctness." The literary definition

would substitute, for the average hearer, a person of high

education living a long time ago; the purpose of this definition

is to make it difficult to speak or write correctly.

The relation of a word to its meaning is of the nature of a

causal law governing our use of the word and our actions when we

hear it used. There is no more reason why a person who uses a

word correctly should be able to tell what it means than there is

why a planet which is moving correctly should know Kepler's laws.

To illustrate what is meant by "understanding" words and

sentences, let us take instances of various situations.

Suppose you are walking in London with an absent-minded friend,

and while crossing a street you say, "Look out, there's a motor

coming." He will glance round and jump aside without the need of

any "mental" intermediary. There need be no "ideas," but only a

stiffening of the muscles, followed quickly by action. He

"understands" the words, because he does the right thing. Such

"understanding" may be taken to belong to the nerves and brain,

being habits which they have acquired while the language was

being learnt. Thus understanding in this sense may be reduced to

mere physiological causal laws.

If you say the same thing to a Frenchman with a slight knowledge

of English he will go through some inner speech which may be

represented by "Que dit-il? Ah, oui, une automobile!" After this,

the rest follows as with the Englishman. Watson would contend

that the inner speech must be incipiently pronounced; we should

argue that it MIGHT be merely imaged. But this point is not

important in the present connection.

If you say the same thing to a child who does not yet know the

word "motor," but does know the other words you are using, you

produce a feeling of anxiety and doubt you will have to point and

say, "There, that's a motor." After that the child will roughly

understand the word "motor," though he may include trains and

steam-rollers If this is the first time the child has heard the

word "motor," he may for a long time continue to recall this

scene when he hears the word.

So far we have found four ways of understanding words:

(1) On suitable occasions you use the word properly.

(2) When you hear it you act appropriately.

(3) You associate the word with another word (say in a different

language) which has the appropriate effect on behaviour.

(4) When the word is being first learnt, you may associate it

with an object, which is what it "means," or a representative of

various objects that it "means."

In the fourth case, the word acquires, through association, some

of the same causal efficacy as the object. The word "motor" can

make you leap aside, just as the motor can, but it cannot break

your bones. The effects which a word can share with its object

are those which proceed according to laws other than the general

laws of physics, i.e. those which, according to our terminology,

involve vital movements as opposed to merely mechanical

movements. The effects of a word that we understand are always

mnemic phenomena in the sense explained in Lecture IV, in so far

as they are identical with, or similar to, the effects which the

object itself might have.

So far, all the uses of words that we have considered can be

accounted for on the lines of behaviourism.

But so far we have only considered what may be called the

"demonstrative" use of language, to point out some feature in the

present environment. This is only one of the ways in which

language may be used. There are also its narrative and

imaginative uses, as in history and novels. Let us take as an

instance the telling of some remembered event.

We spoke a moment ago of a child who hears the word "motor" for

the first time when crossing a street along which a motor-car is

approaching. On a later occasion, we will suppose, the child

remembers the incident and relates it to someone else. In this

case, both the active and passive understanding of words is

different from what it is when words are used demonstratively.

The child is not seeing a motor, but only remembering one; the

hearer does not look round in expectation of seeing a motor

coming, but "understands" that a motor came at some earlier time.

The whole of this occurrence is much more difficult to account

for on behaviourist lines. It is clear that, in so far as the

child is genuinely remembering, he has a picture of the past

occurrence, and his words are chosen so as to describe the

picture; and in so far as the hearer is genuinely apprehending

what is said, the hearer is acquiring a picture more or less like

that of the child. It is true that this process may be telescoped

through the operation of the word-habit. The child may not

genuinely remember the incident, but only have the habit of the

appropriate words, as in the case of a poem which we know by

heart, though we cannot remember learning it. And the hearer also

may only pay attention to the words, and not call up any

corresponding picture. But it is, nevertheless, the possibility

of a memory-image in the child and an imagination-image in the

hearer that makes the essence of the narrative "meaning" of the

words. In so far as this is absent, the words are mere counters,

capable of meaning, but not at the moment possessing it.

Yet this might perhaps be regarded as something of an

overstatement. The words alone, without the use of images, may

cause appropriate emotions and appropriate behaviour. The words

have been used in an environment which produced certain

emotions;. by a telescoped process, the words alone are now

capable of producing similar emotions. On these lines it might be

sought to show that images are unnecessary. I do not believe,

however, that we could account on these lines for the entirely

different response produced by a narrative and by a description

of present facts. Images, as contrasted with sensations, are the

response expected during a narrative; it is understood that

present action is not called for. Thus it seems that we must

maintain our distinction words used demonstratively describe and

are intended to lead to sensations, while the same words used in

narrative describe and are only intended to lead to images.

We have thus, in addition to our four previous ways in which

words can mean, two new ways, namely the way of memory and the

way of imagination. That is to say:

(5) Words may be used to describe or recall a memory-image: to

describe it when it already exists, or to recall it when the

words exist as a habit and are known to be descriptive of some

past experience.

(6) Words may be used to describe or create an imagination-image:

to describe it, for example, in the case of a poet or novelist,

or to create it in the ordinary case for giving

information-though, in the latter case, it is intended that the

imagination-image, when created, shall be accompanied by belief

that something of the sort occurred.

These two ways of using words, including their occurrence in

inner speech, may be spoken of together as the use of words in

"thinking." If we are right, the use of words in thinking

depends, at least in its origin, upon images, and cannot be fully

dealt with on behaviourist lines. And this is really the most

essential function of words, namely that, originally through

their connection with images, they bring us into touch with what

is remote in time or space. When they operate without the medium

of images, this seems to be a telescoped process. Thus the

problem of the meaning of words is brought into connection with

the problem of the meaning of images.

To understand the function that words perform in what is called

"thinking," we must understand both the causes and the effects of

their occurrence. The causes of the occurrence of words require

somewhat different treatment according as the object designated

by the word is sensibly present or absent. When the object is

present, it may itself be taken as the cause of the word, through

association. But when it is absent there is more difficulty in

obtaining a behaviourist theory of the occurrence of the word.

The language-habit consists not merely in the use of words

demonstratively, but also in their use to express narrative or

desire. Professor Watson, in his account of the acquisition of

the language-habit, pays very little attention to the use of

words in narrative and desire. He says ("Behavior," pp. 329-330):

"The stimulus (object) to which the child often responds, a box,

e.g. by movements such as opening and closing and putting objects

into it, may serve to illustrate our argument. The nurse,

observing that the child reacts with his hands, feet, etc., to

the box, begins to say 'box' when the child is handed the box,

'open box' when the child opens it, 'close box' when he closes

it, and 'put doll in box ' when that act is executed. This is

repeated over and over again. In the process of time it comes

about that without any other stimulus than that of the box which

originally called out the bodily habits, he begins to say 'box'

when he sees it, 'open box' when he opens it, etc. The visible

box now becomes a stimulus capable of releasing either the bodily

habits or the word-habit, i.e. development has brought about two

things : (1) a series of functional connections among arcs which

run from visual receptor to muscles of throat, and (2) a series

of already earlier connected arcs which run from the same

receptor to the bodily muscles.... The object meets the child's

vision. He runs to it and tries to reach it and says 'box.'...

Finally the word is uttered without the movement of going towards

the box being executed.... Habits are formed of going to the box

when the arms are full of toys. The child has been taught to

deposit them there. When his arms are laden with toys and no box

is there, the word-habit arises and he calls 'box'; it is handed

to him, and he opens it and deposits the toys therein. This

roughly marks what we would call the genesis of a true

language-habit."(pp. 329-330).*

* Just the same account of language is given in Professor

Watson's more recent book (reference above).

We need not linger over what is said in the above passage as to

the use of the word "box" in the presence of the box. But as to

its use in the absence of the box, there is only one brief

sentence, namely: "When his arms are laden with toys and no box

is there, the word-habit arises and he calls 'box.' " This is

inadequate as it stands, since the habit has been to use the word

when the box is present, and we have to explain its extension to

cases in which the box is absent.

Having admitted images, we may say that the word "box," in the

absence of the box, is caused by an image of the box. This may or

may not be true--in fact, it is true in some cases but not in

others. Even, however, if it were true in all cases, it would

only slightly shift our problem: we should now have to ask what

causes an image of the box to arise. We might be inclined to say

that desire for the box is the cause. But when this view is

investigated, it is found that it compels us to suppose that the

box can be desired without the child's having either an image of

the box or the word "box." This will require a theory of desire

which may be, and I think is, in the main true, but which removes

desire from among things that actually occur, and makes it merely

a convenient fiction, like force in mechanics.* With such a view,

desire is no longer a true cause, but merely a short way of

describing certain processes.

* See Lecture III, above.

In order to explain the occurrence of either the word or the

image in the absence of the box, we have to assume that there is

something, either in the environment or in our own sensations,

which has frequently occurred at about the same time as the word

"box." One of the laws which distinguish psychology (or

nerve-physiology?) from physics is the law that, when two things

have frequently existed in close temporal contiguity, either

comes in time to cause the other.* This is the basis both of

habit and of association. Thus, in our case, the arms full of

toys have frequently been followed quickly by the box, and the

box in turn by the word "box." The box itself is subject to

physical laws, and does not tend to be caused by the arms full of

toys, however often it may in the past have followed them--always

provided that, in the case in question, its physical position is

such that voluntary movements cannot lead to it. But the word

"box" and the image of the box are subject to the law of habit;

hence it is possible for either to be caused by the arms full of

toys. And we may lay it down generally that, whenever we use a

word, either aloud or in inner speech, there is some sensation or

image (either of which may be itself a word) which has frequently

occurred at about the same time as the word, and now, through

habit, causes the word. It follows that the law of habit is

adequate to account for the use of words in the absence of their

objects; moreover, it would be adequate even without introducing

images. Although, therefore, images seem undeniable, we cannot

derive an additional argument in their favour from the use of

words, which could, theoretically, be explained without

introducing images.

*For a more exact statement of this law, with the limitations

suggested by experiment, see A. Wohlgemuth, "On Memory and the

Direction of Associations," "British Journal of Psychology," vol.

v, part iv (March, 1913).

When we understand a word, there is a reciprocal association

between it and the images of what it "means." Images may cause us

to use words which mean them, and these words, heard or read, may

in turn cause the appropriate images. Thus speech is a means of

producing in our hearers the images which are in us. Also, by a

telescoped process, words come in time to produce directly the

effects which would have been produced by the images with which

they were associated. The general law of telescoped processes is

that, if A causes B and B causes C, it will happen in time that A

will cause C directly, without the intermediary of B. This is a

characteristic of psychological and neural causation. In virtue

of this law, the effects of images upon our actions come to be

produced by words, even when the words do not call up appropriate

images. The more familiar we are with words, the more our

"thinking" goes on in words instead of images. We may, for

example, be able to describe a person's appearance correctly

without having at any time had any image of him, provided, when

we saw him, we thought of words which fitted him; the words alone

may remain with us as a habit, and enable us to speak as if we

could recall a visual image of the man. In this and other ways

the understanding of a word often comes to be quite free from

imagery; but in first learning the use of language it would seem

that imagery always plays a very important part.

Images as well as words may be said to have "meaning"; indeed,

the meaning of images seems more primitive than the meaning of

words. What we call (say) an image of St. Paul's may be said to

"mean" St. Paul's. But it is not at all easy to say exactly what

constitutes the meaning of an image. A memory-image of a

particular occurrence, when accompanied by a memory-belief, may

be said to mean the occurrence of which it is an image. But most

actual images do not have this degree of definiteness. If we call

up an image of a dog, we are very likely to have a vague image,

which is not representative of some one special dog, but of dogs

in general. When we call up an image of a friend's face, we are

not likely to reproduce the expression he had on some one

particular occasion, but rather a compromise expression derived

from many occasions. And there is hardly any limit to the

vagueness of which images are capable. In such cases, the meaning

of the image, if defined by relation to the prototype, is vague:

there is not one definite prototype, but a number, none of which

is copied exactly.*

* Cf. Semon, Mnemische Empfindungen, chap. xvi, especially pp.


There is, however, another way of approaching the meaning of

images, namely through their causal efficacy. What is called an

image "of" some definite object, say St. Paul's, has some of the

effects which the object would have. This applies especially to

the effects that depend upon association. The emotional effects,

also, are often similar: images may stimulate desire almost as

strongly as do the objects they represent. And conversely desire

may cause images*: a hungry man will have images of food, and so

on. In all these ways the causal laws concerning images are

connected with the causal laws concerning the objects which the

images "mean." An image may thus come to fulfil the function of a

general idea. The vague image of a dog, which we spoke of a

moment ago, will have effects which are only connected with dogs

in general, not the more special effects which would be produced

by some dogs but not by others. Berkeley and Hume, in their

attack on general ideas, do not allow for the vagueness of

images: they assume that every image has the definiteness that a

physical object would have This is not the case, and a vague

image may well have a meaning which is general.

* This phrase is in need of interpretation, as appears from the

analysis of desire. But the reader can easily supply the

interpretation for himself.

In order to define the "meaning" of an image, we have to take

account both of its resemblance to one or more prototypes, and of

its causal efficacy. If there were such a thing as a pure

imagination-image, without any prototype whatever, it would be

destitute of meaning. But according to Hume's principle, the

simple elements in an image, at least, are derived from

prototypes-except possibly in very rare exceptional cases. Often,

in such instances as our image of a friend's face or of a

nondescript dog, an image is not derived from one prototype, but

from many; when this happens, the image is vague, and blurs the

features in which the various prototypes differ. To arrive at the

meaning of the image in such a case, we observe that there are

certain respects, notably associations, in which the effects of

images resemble those of their prototypes. If we find, in a given

case, that our vague image, say, of a nondescript dog, has those

associative effects which all dogs would have, but not those

belonging to any special dog or kind of dog, we may say that our

image means "dog" in general. If it has all the associations

appropriate to spaniels but no others, we shall say it means

"spaniel"; while if it has all the associations appropriate to

one particular dog, it will mean that dog, however vague it may

be as a picture. The meaning of an image, according to this

analysis, is constituted by a combination of likeness and

associations. It is not a sharp or definite conception, and in

many cases it will be impossible to decide with any certainty

what an image means. I think this lies in the nature of things,

and not in defective analysis.

We may give somewhat more precision to the above account of the

meaning of images, and extend it to meaning in general. We find

sometimes that, IN MNEMIC CAUSATION, an image or word, as

stimulus, has the same effect (or very nearly the same effect) as

would belong to some object, say, a certain dog. In that case we

say that the image or word means that object. In other cases the

mnemic effects are not all those of one object, but only those

shared by objects of a certain kind, e.g. by all dogs. In this

case the meaning of the image or word is general: it means the

whole kind. Generality and particularity are a matter of degree.

If two particulars differ sufficiently little, their mnemic

effects will be the same; therefore no image or word can mean the

one as opposed to the other; this sets a bound to the

particularity of meaning. On the other hand, the mnemic effects

of a number of sufficiently dissimilar objects will have nothing

discoverable in common; hence a word which aims at complete

generality, such as "entity" for example, will have to be devoid

of mnemic effects, and therefore of meaning. In practice, this is

not the case: such words have VERBAL associations, the learning

of which constitutes the study of metaphysics.

The meaning of a word, unlike that of an image, is wholly

constituted by mnemic causal laws, and not in any degree by

likeness (except in exceptional cases). The word "dog" bears no

resemblance to a dog, but its effects, like those of an image of

a dog, resemble the effects of an actual dog in certain respects.

It is much easier to say definitely what a word means than what

an image means, since words, however they originated, have been

framed in later times for the purpose of having meaning, and men

have been engaged for ages in giving increased precision to the

meanings of words. But although it is easier to say what a word

means than what an image means, the relation which constitutes

meaning is much the same in both cases. A word, like an image,

has the same associations as its meaning has. In addition to

other associations, it is associated with images of its meaning,

so that the word tends to call up the image and the image tends

to call up the word., But this association is not essential to

the intelligent use of words. If a word has the right

associations with other objects, we shall be able to use it

correctly, and understand its use by others, even if it evokes no

image. The theoretical understanding of words involves only the

power of associating them correctly with other words; the

practical understanding involves associations with other bodily


The use of words is, of course, primarily social, for the purpose

of suggesting to others ideas which we entertain or at least wish

them to entertain. But the aspect of words that specially

concerns us is their power of promoting our own thought. Almost

all higher intellectual activity is a matter of words, to the

nearly total exclusion of everything else. The advantages of

words for purposes of thought are so great that I should never

end if I were to enumerate them. But a few of them deserve to be


In the first place, there is no difficulty in producing a word,

whereas an image cannot always be brought into existence at will,

and when it comes it often contains much irrelevant detail. In

the second place, much of our thinking is concerned with abstract

matters which do not readily lend themselves to imagery, and are

apt to be falsely conceived if we insist upon finding images that

may be supposed to represent them. The word is always concrete

and sensible, however abstract its meaning may be, and thus by

the help of words we are able to dwell on abstractions in a way

which would otherwise be impossible. In the third place, two

instances of the same word are so similar that neither has

associations not capable of being shared by the other. Two

instances of the word "dog" are much more alike than (say) a pug

and a great dane; hence the word "dog" makes it much easier to

think about dogs in general. When a number of objects have a

common property which is important but not obvious, the invention

of a name for the common property helps us to remember it and to

think of the whole set of objects that possess it. But it is

unnecessary to prolong the catalogue of the uses of language in


At the same time, it is possible to conduct rudimentary thought

by means of images, and it is important, sometimes, to check

purely verbal thought by reference to what it means. In

philosophy especially the tyranny of traditional words is

dangerous, and we have to be on our guard against assuming that

grammar is the key to metaphysics, or that the structure of a

sentence corresponds at all accurately with the structure of the

fact that it asserts. Sayce maintained that all European

philosophy since Aristotle has been dominated by the fact that

the philosophers spoke Indo-European languages, and therefore

supposed the world, like the sentences they were used to,

necessarily divisible into subjects and predicates. When we come

to the consideration of truth and falsehood, we shall see how

necessary it is to avoid assuming too close a parallelism between

facts and the sentences which assert them. Against such errors,

the only safeguard is to be able, once in a way, to discard words

for a moment and contemplate facts more directly through images.

Most serious advances in philosophic thought result from some

such comparatively direct contemplation of facts. But the outcome

has to be expressed in words if it is to be communicable. Those

who have a relatively direct vision of facts are often incapable

of translating their vision into words, while those who possess

the words have usually lost the vision. It is partly for this

reason that the highest philosophical capacity is so rare: it

requires a combination of vision with abstract words which is

hard to achieve, and too quickly lost in the few who have for a

moment achieved it.


It is said to be one of the merits of the human mind that it is

capable of framing abstract ideas, and of conducting

nonsensational thought. In this it is supposed to differ from the

mind of animals. From Plato onward the "idea" has played a great

part in the systems of idealizing philosophers. The "idea" has

been, in their hands, always something noble and abstract, the

apprehension and use of which by man confers upon him a quite

special dignity.

The thing we have to consider to-day is this: seeing that there

certainly are words of which the meaning is abstract, and seeing

that we can use these words intelligently, what must be assumed

or inferred, or what can be discovered by observation, in the way

of mental content to account for the intelligent use of abstract


Taken as a problem in logic, the answer is, of course, that

absolutely nothing in the way of abstract mental content is

inferable from the mere fact that we can use intelligently words

of which the meaning is abstract. It is clear that a sufficiently

ingenious person could manufacture a machine moved by olfactory

stimuli which, whenever a dog appeared in its neighbourhood,

would say, "There is a dog," and when a cat appeared would throw

stones at it. The act of saying "There is a dog," and the act of

throwing stones, would in such a case be equally mechanical.

Correct speech does not of itself afford any better evidence of

mental content than the performance of any other set of

biologically useful movements, such as those of flight or combat.

All that is inferable from language is that two instances of a

universal, even when they differ very greatly, may cause the

utterance of two instances of the same word which only differ

very slightly. As we saw in the preceding lecture, the word "dog"

is useful, partly, because two instances of this word are much

more similar than (say) a pug and a great dane. The use of words

is thus a method of substituting for two particulars which differ

widely, in spite of being instances of the same universal, two

other particulars which differ very little, and which are also

instances of a universal, namely the name of the previous

universal. Thus, so far as logic is concerned, we are entirely

free to adopt any theory as to general ideas which empirical

observation may recommend.

Berkeley and Hume made a vigorous onslaught on "abstract ideas."

They meant by an idea approximately what we should call an image.

Locke having maintained that he could form an idea of triangle in

general, without deciding what sort of triangle it was to be,

Berkeley contended that this was impossible. He says:

"Whether others,have this wonderful faculty of abstracting their

ideas, they best can tell: for myself, I dare be confident I have

it not. I find, indeed, I have indeed a faculty of imagining, or

representing to myself, the ideas of those particular things I

have perceived, and of variously compounding and dividing them. I

can imagine a man with two heads, or the upper parts of a man

joined to the body of a horse. I can consider the hand, the eye,

the nose, each by itself abstracted or separated from the rest of

the body. But, then, whatever hand or eye I imagine, it must have

some particular shape and colour. Likewise the idea of a man that

I frame to myself must be either of a white, or a black, or a

tawny, a straight, or a crooked, a tall, or a low, or a

middle-sized man. I cannot by any effort of thought conceive the

abstract idea above described. And it is equally impossible for

me to form the abstract idea of motion distinct from the body

moving, and which is neither swift nor slow, curvilinear nor

rectilinear; and the like may be said of all other abstract

general ideas whatsoever. To be plain, I own myself able to

abstract in one sense, as when I consider some particular parts

of qualities separated from others, with which, though they are

united in some object, yet it is possible they may really exist

without them. But I deny that I can abstract from one another, or

conceive separately, those qualities which it is impossible

should exist so separated; or that I can frame a general notion,

by abstracting from particulars in the manner aforesaid--which

last are the two proper acceptations of ABSTRACTION. And there is

ground to think most men will acknowledge themselves to be in my

case. The generality of men which are simple and illiterate never

pretend to ABSTRACT NOTIONS. It is said they are difficult and

not to be attained without pains and study; we may therefore

reasonably conclude that, if such there be, they are confined

only to the learned.

"I proceed to examine what can be alleged in defence of the

doctrine of abstraction, and try if I can discover what it is

that inclines the men of speculation to embrace an opinion so

remote from common sense as that seems to be. There has been a

late excellent and deservedly esteemed philosopher who, no doubt,

has given it very much countenance, by seeming to think the

having abstract general ideas is what puts the widest difference

in point of understanding betwixt man and beast. 'The having of

general ideas,' saith he, 'is that which puts a perfect

distinction betwixt man and brutes, and is an excellency which

the faculties of brutes do by no means attain unto. For, it is

evident we observe no footsteps in them of making use of general

signs for universal ideas; from which we have reason to imagine

that they have not the faculty of abstracting, or making general

ideas, since they have no use of words or any other general

signs.' And a little after: 'Therefore, I think, we may suppose

that it is in this that the species of brutes are discriminated

from men, and it is that proper difference wherein they are

wholly separated, and which at last widens to so wide a distance.

For, if they have any ideas at all, and are not bare machines (as

some would have them), we cannot deny them to have some reason.

It seems as evident to me that they do, some of them, in certain

instances reason as that they have sense; but it is only in

particular ideas, just as they receive them from their senses.

They are the best of them tied up within those narrow bounds, and

have not (as I think) the faculty to enlarge them by any kind of

abstraction.* ("Essay on Human Understanding," Bk. II, chap. xi,

paragraphs 10 and 11.) I readily agree with this learned author,

that the faculties of brutes can by no means attain to

abstraction. But, then, if this be made the distinguishing

property of that sort of animals, I fear a great many of those

that pass for men must be reckoned into their number. The reason

that is here assigned why we have no grounds to think brutes have

abstract general ideas is, that we observe in them no use of

words or any other general signs; which is built on this

supposition-that the making use of words implies the having

general ideas. From which it follows that men who use language

are able to abstract or generalize their ideas. That this is the

sense and arguing of the author will further appear by his

answering the question he in another place puts: 'Since all

things that exist are only particulars, how come we by general

terms?' His answer is: 'Words become general by being made the

signs of general ideas.' ("Essay on Human Understanding," Bk.

III, chap. III, paragraph 6.) But it seems that a word becomes

general by being made the sign, not of an abstract general idea,

but of several particular ideas, any one of which it

indifferently suggests to the mind. For example, when it is said

'the change of motion is proportional to the impressed force,' or

that 'whatever has extension is divisible,' these propositions

are to be understood of motion and extension in general; and

nevertheless it will not follow that they suggest to my thoughts

an idea of motion without a body moved, or any determinate

direction and velocity, or that I must conceive an abstract

general idea of extension, which is neither line, surface, nor

solid, neither great nor small, black, white, nor red, nor of any

other determinate colour. It is only implied that whatever

particular motion I consider, whether it be swift or slow,

perpendicular, horizontal, or oblique, or in whatever object, the

axiom concerning it holds equally true. As does the other of

every particular extension, it matters not whether line, surface,

or solid, whether of this or that magnitude or figure.

"By observing how ideas become general, we may the better judge

how words are made so. And here it is to be noted that I do not

deny absolutely there are general ideas, but only that there are

any ABSTRACT general ideas; for, in the passages we have quoted

wherein there is mention of general ideas, it is always supposed

that they are formed by abstraction, after the manner set forth

in sections 8 and 9. Now, if we will annex a meaning to our

words, and speak only of what we can conceive, I believe we shall

acknowledge that an idea which, considered in itself, is

particular, becomes general by being made to represent or stand

for all other particular ideas of the same sort. To make this

plain by an example, suppose a geometrician is demonstrating the

method of cutting a line in two equal parts. He draws, for

instance, a black line of an inch in length: this, which in

itself is a particular line, is nevertheless with regard to its

signification general, since, as it is there used, it represents

all particular lines whatsoever; so that what is demonstrated of

it is demonstrated of all lines, or, in other words, of a line in

general. And, as THAT PARTICULAR LINE becomes general by being

made a sign, so the NAME 'line,' which taken absolutely is

particular, by being a sign is made general. And as the former

owes its generality not to its being the sign of an abstract or

general line, but of all particular right lines that may possibly

exist, so the latter must be thought to derive its generality

from the same cause, namely, the various particular lines which

it indifferently denotes." *

* Introduction to "A Treatise concerning the Principles of Human

Knowledge," paragraphs 10, 11, and 12.

Berkeley's view in the above passage, which is essentially the

same as Hume's, does not wholly agree with modern psychology,

although it comes nearer to agreement than does the view of those

who believe that there are in the mind single contents which can

be called abstract ideas. The way in which Berkeley's view is

inadequate is chiefly in the fact that images are as a rule not

of one definite prototype, but of a number of related similar

prototypes. On this subject Semon has written well. In "Die

Mneme," pp. 217 ff., discussing the effect of repeated similar

stimuli in producing and modifying our images, he says: "We

choose a case of mnemic excitement whose existence we can

perceive for ourselves by introspection, and seek to ekphore the

bodily picture of our nearest relation in his absence, and have

thus a pure mnemic excitement before us. At first it may seem to

us that a determinate quite concrete picture becomes manifest in

us, but just when we are concerned with a person with whom we are

in constant contact, we shall find that the ekphored picture has

something so to speak generalized. It is something like those

American photographs which seek to display what is general about

a type by combining a great number of photographs of different

heads over each other on one plate. In our opinion, the

generalizations happen by the homophonic working of different

pictures of the same face which we have come across in the most

different conditions and situations, once pale, once reddened,

once cheerful, once earnest, once in this light, and once in

that. As soon as we do not let the whole series of repetitions

resound in us uniformly, but give our attention to one particular

moment out of the many... this particular mnemic stimulus at once

overbalances its simultaneously roused predecessors and

successors, and we perceive the face in question with concrete

definiteness in that particular situation." A little later he

says: "The result is--at least in man, but probably also in the

higher animals--the development of a sort of PHYSIOLOGICAL

abstraction. Mnemic homophony gives us, without the addition of

other processes of thought, a picture of our friend X which is in

a certain sense abstract, not the concrete in any one situation,

but X cut loose from any particular point of time. If the circle

of ekphored engrams is drawn even more widely, abstract pictures

of a higher order appear: for instance, a white man or a negro.

In my opinion, the first form of abstract concepts in general is

based upon such abstract pictures. The physiological abstraction

which takes place in the above described manner is a predecessor

of purely logical abstraction. It is by no means a monopoly of

the human race, but shows itself in various ways also among the

more highly organized animals." The same subject is treated in

more detail in Chapter xvi of "Die mnemischen Empfindungen," but

what is said there adds nothing vital to what is contained in the

above quotations.

It is necessary, however, to distinguish between the vague and

the general. So long as we are content with Semon's composite

image, we MAY get no farther than the vague. The question whether

this image takes us to the general or not depends, I think, upon

the question whether, in addition to the generalized image, we

have also particular images of some of the instances out of which

it is compounded. Suppose, for example, that on a number of

occasions you had seen one negro, and that you did not know

whether this one was the same or different on the different

occasions. Suppose that in the end you had an abstract

memory-image of the different appearances presented by the negro

on different occasions, but no memory-image of any one of the

single appearances. In that case your image would be vague. If,

on the other hand, you have, in addition to the generalized

image, particular images of the several appearances, sufficiently

clear to be recognized as different, and as instances of the

generalized picture, you will then not feel the generalized

picture to be adequate to any one particular appearance, and you

will be able to make it function as a general idea rather than a

vague idea. If this view is correct, no new general content needs

to be added to the generalized image. What needs to be added is

particular images compared and contrasted with the generalized

image. So far as I can judge by introspection, this does occur in

practice. Take for example Semon's instance of a friend's face.

Unless we make some special effort of recollection, the face is

likely to come before us with an average expression, very blurred

and vague, but we can at will recall how our friend looked on

some special occasion when he was pleased or angry or unhappy,

and this enables us to realize the generalized character of the

vague image.

There is, however, another way of distinguishing between the

vague, the particular and the general, and this is not by their

content, but by the reaction which they produce. A word, for

example, may be said to be vague when it is applicable to a

number of different individuals, but to each as individuals; the

name Smith, for example, is vague: it is always meant to apply to

one man, but there are many men to each of whom it applies.* The

word "man," on the other hand, is general. We say, "This is

Smith," but we do not say "This is man," but "This is a man."

Thus we may say that a word embodies a vague idea when its

effects are appropriate to an individual, but are the same for

various similar individuals, while a word embodies a general idea

when its effects are different from those appropriate to

individuals. In what this difference consists it is, however, not

easy to say. I am inclined to think that it consists merely in

the knowledge that no one individual is represented, so that what

distinguishes a general idea from a vague idea is merely the

presence of a certain accompanying belief. If this view is

correct, a general idea differs from a vague one in a way

analogous to that in which a memory-image differs from an

imagination-image. There also we found that the difference

consists merely of the fact that a memory-image is accompanied by

a belief, in this case as to the past.

* "Smith" would only be a quite satisfactory representation of

vague words if we failed to discriminate between different people

called Smith.

It should also be said that our images even of quite particular

occurrences have always a greater or a less degree of vagueness.

That is to say, the occurrence might have varied within certain

limits without causing our image to vary recognizably. To arrive

at the general it is necessary that we should be able to contrast

it with a number of relatively precise images or words for

particular occurrences; so long as all our images and words are

vague, we cannot arrive at the contrast by which the general is

defined. This is the justification for the view which I quoted on

p. 184 from Ribot (op. cit., p. 32), viz. that intelligence

progresses from the indefinite to the definite, and that the

vague appears earlier than either the particular or the general.

I think the view which I have been advocating, to the effect that

a general idea is distinguished from a vague one by the presence

of a judgment, is also that intended by Ribot when he says (op.

cit., p. 92): "The generic image is never, the concept is always,

a judgment. We know that for logicians (formerly at any rate) the

concept is the simple and primitive element; next comes the

judgment, uniting two or several concepts; then ratiocination,

combining two or several judgments. For the psychologists, on the

contrary, affirmation is the fundamental act; the concept is the

result of judgment (explicit or implicit), of similarities with

exclusion of differences."

A great deal of work professing to be experimental has been done

in recent years on the psychology of thought. A good summary of

such work up to the year agog is contained in Titchener's

"Lectures on the Experimental Psychology of the Thought

Processes" (1909). Three articles in the "Archiv fur die gesammte

Psychologie" by Watt,* Messer** and Buhler*** contain a great

deal of the material amassed by the methods which Titchener calls


* Henry J. Watt, "Experimentelle Beitrage zu einer Theorie des

Denkens," vol. iv (1905) pp. 289-436.

** August Messer, "Experimentell-psychologische Untersuchu gen

uber das Denken," vol. iii (1906), pp. 1-224.

*** Karl Buhler, "Uber Gedanken," vol. ix (1907), pp. 297-365.

For my part I am unable to attach as much importance to this work

as many psychologists do. The method employed appears to me

hardly to fulfil the conditions of scientific experiment. Broadly

speaking, what is done is, that a set of questions are asked of

various people, their answers are recorded, and likewise their

own accounts, based upon introspection, of the processes of

thought which led them to give those answers. Much too much

reliance seems to me to be placed upon the correctness of their

introspection. On introspection as a method I have spoken earlier

(Lecture VI). I am not prepared, like Professor Watson, to reject

it wholly, but I do consider that it is exceedingly fallible and

quite peculiarly liable to falsification in accordance with

preconceived theory. It is like depending upon the report of a

shortsighted person as to whom he sees coming along the road at a

moment when he is firmly convinced that Jones is sure to come. If

everybody were shortsighted and obsessed with beliefs as to what

was going to be visible, we might have to make the best of such

testimony, but we should need to correct its errors by taking

care to collect the simultaneous evidence of people with the most

divergent expectations. There is no evidence that this was done

in the experiments in question, nor indeed that the influence of

theory in falsifying the introspection was at all adequately

recognized. I feel convinced that if Professor Watson had been

one of the subjects of the questionnaires, he would have given

answers totally different from those recorded in the articles in

question. Titchener quotes an opinion of Wundt on these

investigations, which appears to me thoroughly justified. "These

experiments," he says, "are not experiments at all in the sense

of a scientific methodology; they are counterfeit experiments,

that seem methodical simply because they are ordinarily performed

in a psychological laboratory, and involve the co-operation of

two persons, who purport to be experimenter and observer. In

reality, they are as unmethodical as possible; they possess none

of the special features by which we distinguish the

introspections of experimental psychology from the casual

introspections of everyday life."* Titchener, of course, dissents

from this opinion, but I cannot see that his reasons for dissent

are adequate. My doubts are only increased by the fact that

Buhler at any rate used trained psychologists as his subjects. A

trained psychologist is, of course, supposed to have acquired the

habit of observation, but he is at least equally likely to have

acquired a habit of seeing what his theories require. We may take

Buhler's "Uber Gedanken" to illustrate the kind of results

arrived at by such methods. Buhler says (p. 303): "We ask

ourselves the general question: 'WHAT DO WE EXPERIENCE WHEN WE

THINK?' Then we do not at all attempt a preliminary determination

of the concept 'thought,' but choose for analysis only such

processes as everyone would describe as processes of thought."

The most important thing in thinking, he says, is "awareness

that..." (Bewusstheit dass), which he calls a thought. It is, he

says, thoughts in this sense that are essential to thinking.

Thinking, he maintains, does not need language or sensuous

presentations. "I assert rather that in principle every object

can be thought (meant) distinctly, without any help from sensuous

presentation (Anschauungshilfen). Every individual shade of blue

colour on the picture that hangs in my room I can think with

complete distinctness unsensuously (unanschaulich), provided it

is possible that the object should be given to me in another

manner than by the help of sensations. How that is possible we

shall see later." What he calls a thought (Gedanke) cannot be

reduced, according to him, to other psychic occurrences. He

maintains that thoughts consist for the most part of known rules

(p. 342). It is clearly essential to the interest of this theory

that the thought or rule alluded to by Buhler should not need to

be expressed in words, for if it is expressed in words it is

immediately capable of being dealt with on the lines with which

the behaviourists have familiarized us. It is clear also that the

supposed absence of words rests solely upon the introspective

testimony of the persons experimented upon. I cannot think that

there is sufficient certainty of their reliability in this

negative observation to make us accept a difficult and

revolutionary view of thought, merely because they have failed to

observe the presence of words or their equivalent in their

thinking. I think it far more likely, especially in view of the

fact that the persons concerned were highly educated, that we are

concerned with telescoped processes, in which habit has caused a

great many intermediate terms to be elided or to be passed over

so quickly as to escape observation.

* Titchener, op. cit., p. 79.

I am inclined to think that similar remarks apply to the general

idea of "imageless thinking," concerning which there has been

much controversy. The advocates of imageless thinking are not

contending merely that there can be thinking which is purely

verbal; they are contending that there can be thinking which

proceeds neither in words nor in images. My own feeling is that

they have rashly assumed the presence of thinking in cases where

habit has rendered thinking unnecessary. When Thorndike

experimented with animals in cages, he found that the

associations established were between a sensory stimulus and a

bodily movement (not the idea of it), without the need of

supposing any non-physiological intermediary (op. cit., p. 100

ff.). The same thing, it seems to me, applies to ourselves. A

certain sensory situation produces in us a certain bodily

movement. Sometimes this movement consists in uttering words.

Prejudice leads us to suppose that between the sensory stimulus

and the utterance of the words a process of thought must have

intervened, but there seems no good reason for such a

supposition. Any habitual action, such as eating or dressing, may

be performed on the appropriate occasion, without any need of

thought, and the same seems to be true of a painfully large

proportion of our talk. What applies to uttered speech applies of

course equally to the internal speech which is not uttered. I

remain, therefore, entirely unconvinced that there is any such

phenomenon as thinking which consists neither of images nor of

words, or that "ideas" have to be added to sensations and images

as part of the material out of which mental phenomena are built.

The question of the nature of our consciousness of the universal

is much affected by our view as to the general nature of the

relation of consciousness to its object. If we adopt the view of

Brentano, according to which all mental content has essential

reference to an object, it is then natural to suppose that there

is some peculiar kind of mental content of which the object is a

universal, as oppose to a particular. According to this view, a

particular cat can be PERceived or imagined, while the universal

"cat" is CONceived. But this whole manner of viewing our dealings

with universals has to be abandoned when the relation of a mental

occurrence to its "object" is regarded as merely indirect and

causal, which is the view that we have adopted. The mental

content is, of course, always particular, and the question as to

what it "means" (in case it means anything) is one which cannot

be settled by merely examining the intrinsic character of the

mental content, but only by knowing its causal connections in the

case of the person concerned. To say that a certain thought

"means" a universal as opposed to either a vague or a particular,

is to say something exceedingly complex. A horse will behave in a

certain manner whenever he smells a bear, even if the smell is

derived from a bearskin. That is to say, any environment

containing an instance of the universal "smell of a bear"

produces closely similar behaviour in the horse, but we do not

say that the horse is conscious of this universal. There is

equally little reason to regard a man as conscious of the same

universal, because under the same circumstances he can react by

saying, "I smell a bear." This reaction, like that of the horse,

is merely closely similar on different occasions where the

environment affords instances of the same universal. Words of

which the logical meaning is universal can therefore be employed

correctly, without anything that could be called consciousness of

universals. Such consciousness in the only sense in which it can

be said to exist is a matter of reflective judgment consisting in

the observation of similarities and differences. A universal

never appears before the mind as a single object in the sort of

way in which something perceived appears. I THINK a logical

argument could be produced to show that universals are part of

the structure of the world, but they are an inferred part, not a

part of our data. What exists in us consists of various factors,

some open to external observation, others only visible to

introspection. The factors open to external observation are

primarily habits, having the peculiarity that very similar

reactions are produced by stimuli which are in many respects very

different from each other. Of this the reaction of the horse to

the smell of the bear is an instance, and so is the reaction of

the man who says "bear" under the same circumstances. The verbal

reaction is, of course, the most important from the point of view

of what may be called knowledge of universals. A man who can

always use the word "dog" when he sees a dog may be said, in a

certain sense, to know the meaning of the word "dog," and IN THAT

SENSE to have knowledge of the universal "dog." But there is, of

course, a further stage reached by the logician in which he not

merely reacts with the word "dog," but sets to work to discover

what it is in the environment that causes in him this almost

identical reaction on different occasions. This further stage

consists in knowledge of similarities and differences:

similarities which are necessary to the applicability of the word

"dog," and differences which are compatible with it. Our

knowledge of these similarities and differences is never

exhaustive, and therefore our knowledge of the meaning of a

universal is never complete.

In addition to external observable habits (including the habit of

words), there is also the generic image produced by the

superposition, or, in Semon's phrase, homophony, of a number of

similar perceptions. This image is vague so long as the

multiplicity of its prototypes is not recognized, but becomes

universal when it exists alongside of the more specific images of

its instances, and is knowingly contrasted with them. In this

case we find again, as we found when we were discussing words in

general in the preceding lecture, that images are not logically

necessary in order to account for observable behaviour, i.e. in

this case intelligent speech. Intelligent speech could exist as a

motor habit, without any accompaniment of images, and this

conclusion applies to words of which the meaning is universal,

just as much as to words of which the meaning is relatively

particular. If this conclusion is valid, it follows that

behaviourist psychology, which eschews introspective data, is

capable of being an independent science, and of accounting for

all that part of the behaviour of other people which is commonly

regarded as evidence that they think. It must be admitted that

this conclusion considerably weakens the reliance which can be

placed upon introspective data. They must be accepted simply on

account of the fact that we seem to perceive them, not on account

of their supposed necessity for explaining the data of external


This, at any rate, is the conclusion to which. we are forced, so

long as, with the behaviourists, we accept common-sense views of

the physical world. But if, as I have urged, the physical world

itself, as known, is infected through and through with

subjectivity, if, as the theory of relativity suggests, the

physical universe contains the diversity of points of view which

we have been accustomed to regard as distinctively psychological,

then we are brought back by this different road to the necessity

for trusting observations which are in an important sense

private. And it is the privacy of introspective data which causes

much of the behaviourists' objection to them.

This is an example of the difficulty of constructing an adequate

philosophy of any one science without taking account of other

sciences. The behaviourist philosophy of psychology, though in

many respects admirable from the point of view of method, appears

to me to fail in the last analysis because it is based upon an

inadequate philosophy of physics. In spite, therefore, of the

fact that the evidence for images, whether generic or particular,

is merely introspective, I cannot admit that images should be

rejected, or that we should minimize their function in our

knowledge of what is remote in time or space.


Belief, which is our subject to-day, is the central problem in

the analysis of mind. Believing seems the most "mental" thing we

do, the thing most remote from what is done by mere matter. The

whole intellectual life consists of beliefs, and of the passage

from one belief to another by what is called "reasoning." Beliefs

give knowledge and error; they are the vehicles of truth and

falsehood. Psychology, theory of knowledge and metaphysics

revolve about belief, and on the view we take of belief our

philosophical outlook largely depends.

Before embarking upon the detailed analysis of belief, we shall

do well to note certain requisites which any theory must fulfil.

(1) Just as words are characterized by meaning, so beliefs are

characterized by truth or falsehood. And just as meaning consists

in relation to the object meant, so truth and falsehood consist

in relation to something that lies outside the belief. You may

believe that such-and-such a horse will win the Derby. The time

comes, and your horse wins or does not win; according to the

outcome, your belief was true or false. You may believe that six

times nine is fifty-six; in this case also there is a fact which

makes your belief false. You may believe that America was

discovered in 1492, or that it was discovered in 1066. In the one

case your belief is true, in the other false; in either case its

truth or falsehood depends upon the actions of Columbus, not upon

anything present or under your control. What makes a belief true

or false I call a "fact." The particular fact that makes a given

belief true or false I call its "objective,"* and the relation of

the belief to its objective I call the "reference" or the

"objective reference" of the belief. Thus, if I believe that

Columbus crossed the Atlantic in 1492, the "objective" of my

belief is Columbus's actual voyage, and the "reference" of my

belief is the relation between my belief and the voyage--that

relation, namely, in virtue of which the voyage makes my belief

true (or, in another case, false). "Reference" of beliefs differs

from "meaning" of words in various ways, but especially in the

fact that it is of two kinds, "true" reference and "false"

reference. The truth or falsehood of a belief does not depend

upon anything intrinsic to the belief, but upon the nature of its

relation to its objective. The intrinsic nature of belief can be

treated without reference to what makes it true or false. In the

remainder of the present lecture I shall ignore truth and

falsehood, which will be the subject of Lecture XIII. It is the

intrinsic nature of belief that will concern us to-day.

* This terminology is suggested by Meinong, but is not exactly

the same as his.

(2) We must distinguish between believing and what is believed. I

may believe that Columbus crossed the Atlantic, that all Cretans

are liars, that two and two are four, or that nine times six is

fifty-six; in all these cases the believing is just the same, and

only the contents believed are different. I may remember my

breakfast this morning, my lecture last week, or my first sight

of New York. In all these cases the feeling of memory-belief is

just the same, and only what is remembered differs. Exactly

similar remarks apply to expectations. Bare assent, memory and

expectation are forms of belief; all three are different from

what is believed, and each has a constant character which is

independent of what is believed.

In Lecture I we criticized the analysis of a presentation into

act, content and object. But our analysis of belief contains

three very similar elements, namely the believing, what is

believed and the objective. The objections to the act (in the

case of presentations) are not valid against the believing in the

case of beliefs, because the believing is an actual experienced

feeling, not something postulated, like the act. But it is

necessary first to complete our preliminary requisites, and then

to examine the content of a belief. After that, we shall be in a

position to return to the question as to what constitutes


(3) What is believed, and the believing, must both consist of

present occurrences in the believer, no matter what may be the

objective of the belief. Suppose I believe, for example, "that

Caesar crossed the Rubicon." The objective of my belief is an

event which happened long ago, which I never saw and do not

remember. This event itself is not in my mind when I believe that

it happened. It is not correct to say that I am believing the

actual event; what I am believing is something now in my mind,

something related to the event (in a way which we shall

investigate in Lecture XIII), but obviously not to be confounded

with the event, since the event is not occurring now but the

believing is. What a man is believing at a given moment is wholly

determinate if we know the contents of his mind at that moment;

but Caesar's crossing of the Rubicon was an historical physical

event, which is distinct from the present contents of every

present mind. What is believed, however true it may be, is not

the actual fact that makes the belief true, but a present event

related to the fact. This present event, which is what is

believed, I shall call the "content" of the belief. We have

already had occasion to notice the distinction between content

and objective in the case of memory-beliefs, where the content is

"this occurred" and the objective is the past event.

(4) Between content and objective there is sometimes a very wide

gulf, for example in the case of "Caesar crossed the Rubicon."

This gulf may, when it is first perceived, give us a feeling that

we cannot really " know " anything about the outer world. All we

can "know," it may be said, is what is now in our thoughts. If

Caesar and the Rubicon cannot be bodily in our thoughts, it might

seem as though we must remain cut off from knowledge of them. I

shall not now deal at length with this feeling, since it is

necessary first to define "knowing," which cannot be done yet.

But I will say, as a preliminary answer, that the feeling assumes

an ideal of knowing which I believe to be quite mistaken. ~ it

assumes, if it is thought out, something like the mystic unity of

knower and known. These two are often said to be combined into a

unity by the fact of cognition; hence when this unity is plainly

absent, it may seem as if there were no genuine cognition. For my

part, I think such theories and feelings wholly mistaken: I

believe knowing to be a very external and complicated relation,

incapable of exact definition, dependent upon causal laws, and

involving no more unity than there is between a signpost and the

town to which it points. I shall return to this question on a

later occasion; for the moment these provisional remarks must


(5) The objective reference of a belief is connected with the

fact that all or some of the constituents of its content have

meaning. If I say "Caesar conquered Gaul," a person who knows the

meaning of the three words composing my statement knows as much

as can be known about the nature of the objective which would

make my statement true. It is clear that the objective reference

of a belief is, in general, in some way derivative from the

meanings of the words or images that occur in its content. There

are, however, certain complications which must be borne in mind.

In the first place, it might be contended that a memory-image

acquires meaning only through the memory-belief, which would

seem, at least in the case of memory, to make belief more

primitive than the meaning of images. In the second place, it is

a very singular thing that meaning, which is single, should

generate objective reference, which is dual, namely true and

false. This is one of the facts which any theory of belief must

explain if it is to be satisfactory.

It is now time to leave these preliminary requisites, and attempt

the analysis of the contents of beliefs.

The first thing to notice about what is believed, i.e. about the

content of a belief, is that it is always complex: We believe

that a certain thing has a certain property, or a certain

relation to something else, or that it occurred or will occur (in

the sense discussed at the end of Lecture IX); or we may believe

that all the members of a certain class have a certain property,

or that a certain property sometimes occurs among the members of

a class; or we may believe that if one thing happens, another

will happen (for example, "if it rains I shall bring my

umbrella"), or we may believe that something does not happen, or

did not or will not happen (for example, "it won't rain"); or

that one of two things must happen (for example, "either you

withdraw your accusation, or I shall bring a libel action"). The

catalogue of the sorts of things we may believe is infinite, but

all of them are complex.

Language sometimes conceals the complexity of a belief. We say

that a person believes in God, and it might seem as if God formed

the whole content of the belief. But what is really believed is

that God exists, which is very far from being simple. Similarly,

when a person has a memory-image with a memory-belief, the belief

is "this occurred," in the sense explained in Lecture IX; and

"this occurred" is not simple. In like manner all cases where the

content of a belief seems simple at first sight will be found, on

examination, to confirm the view that the content is always


The content of a belief involves not merely a plurality of

constituents, but definite relations between them; it is not

determinate when its constituents alone are given. For example,

"Plato preceded Aristotle" and "Aristotle preceded Plato" are

both contents which may be believed, but, although they consist

of exactly the same constituents, they are different, and even


The content of a belief may consist of words only, or of images

only, or of a mixture of the two, or of either or both together

with one or more sensations. It must contain at least one

constituent which is a word or an image, and it may or may not

contain one or more sensations as constituents. Some examples

will make these various possibilities clear.

We may take first recognition, in either of the forms "this is of

such-and-such a kind" or "this has occurred before." In either

case, present sensation is a constituent. For example, you hear a

noise, and you say to yourself "tram." Here the noise and the

word "tram" are both constituents of your belief; there is also a

relation between them, expressed by "is" in the proposition "that

is a tram." As soon as your act of recognition is completed by

the occurrence of the word "tram," your actions are affected: you

hurry if you want the tram, or cease to hurry if you want a bus.

In this case the content of your belief is a sensation (the

noise) and a word ("tram") related in a way which may be called


The same noise may bring into your mind the visual image of a

tram, instead of the word "tram." In this case your belief

consists of a sensation and an image suitable related. Beliefs of

this class are what are called "judgments of perception." As we

saw in Lecture VIII, the images associated with a sensation often

come with such spontaneity and force that the unsophisticated do

not distinguish them from the sensation; it is only the

psychologist or the skilled observer who is aware of the large

mnemic element that is added to sensation to make perception. It

may be objected that what is added consists merely of images

without belief. This is no doubt sometimes the case, but is

certainly sometimes not the case. That belief always occurs in

perception as opposed to sensation it is not necessary for us to

maintain; it is enough for our purposes to note that it sometimes

occurs, and that when it does, the content of our belief consists

of a sensation and an image suitably related.

In a PURE memory-belief only images occur. But a mixture of words

and images is very common in memory. You have an image of the

past occurrence, and you say to yourself: "Yes, that's how it

was." Here the image and the words together make up the content

of the belief. And when the remembering of an incident has become

a habit, it may be purely verbal, and the memory-belief may

consist of words alone.

The more complicated forms of belief tend to consist only of

words. Often images of various kinds accompany them, but they are

apt to be irrelevant, and to form no part of what is actually

believed. For example, in thinking of the Solar System, you are

likely to have vague images of pictures you have seen of the

earth surrounded by clouds, Saturn and his rings, the sun during

an eclipse, and so on; but none of these form part of your belief

that the planets revolve round the sun in elliptical orbits. The

only images that form an actual part of such beliefs are, as a

rule, images of words. And images of words, for the reasons

considered in Lecture VIII, cannot be distinguished with any

certainty from sensations, when, as is often, if not usually, the

case, they are kinaesthetic images of pronouncing the words.

It is impossible for a belief to consist of sensations alone,

except when, as in the case of words, the sensations have

associations which make them signs possessed of meaning. The

reason is that objective reference is of the essence of belief,

and objective reference is derived from meaning. When I speak of

a belief consisting partly of sensations and partly of words, I

do not mean to deny that the words, when they are not mere

images, are sensational, but that they occur as signs, not (so to

speak) in their own right. To revert to the noise of the tram,

when you hear it and say "tram," the noise and the word are both

sensations (if you actually pronounce the word), but the noise is

part of the fact which makes your belief true, whereas the word

is not part of this fact. It is the MEANING of the word "tram,"

not the actual word, that forms part of the fact which is the

objective of your belief. Thus the word occurs in the belief as a

symbol, in virtue of its meaning, whereas the noise enters into

both the belief and its objective. It is this that distinguishes

the occurrence of words as symbols from the occurrence of

sensations in their own right: the objective contains the

sensations that occur in their own right, but contains only the

meanings of the words that occur as symbols.

For the sake of simplicity, we may ignore the cases in which

sensations in their own right form part of the content of a

belief, and confine ourselves to images and words. We may also

omit the cases in which both images and words occur in the

content of a belief. Thus we become confined to two cases: (a)

when the content consists wholly of images, (b) when it consists

wholly of words. The case of mixed images and words has no

special importance, and its omission will do no harm.

Let us take in illustration a case of memory. Suppose you are

thinking of some familiar room. You may call up an image of it,

and in your image the window may be to the left of the door.

Without any intrusion of words, you may believe in the

correctness of your image. You then have a belief, consisting

wholly of images, which becomes, when put into words, "the window

is to the left of the door." You may yourself use these words and

proceed to believe them. You thus pass from an image-content to

the corresponding word-content. The content is different in the

two cases, but its objective reference is the same. This shows

the relation of image-beliefs to word-beliefs in a very simple

case. In more elaborate cases the relation becomes much less


It may be said that even in this very simple case the objective

reference of the word-content is not quite the same as that of

the image-content, that images have a wealth of concrete features

which are lost when words are substituted, that the window in the

image is not a mere window in the abstract, but a window of a

certain shape and size, not merely to the left of the door, but a

certain distance to the left, and so on. In reply, it may be

admitted at once that there is, as a rule, a certain amount of

truth in the objection. But two points may be urged to minimize

its force. First, images do not, as a rule, have that wealth of

concrete detail that would make it IMPOSSIBLE to express them

fully in words. They are vague and fragmentary: a finite number

of words, though perhaps a large number, would exhaust at least

their SIGNIFICANT features. For--and this is our second

point--images enter into the content of a belief through the fact

that they are capable of meaning, and their meaning does not, as

a rule, have as much complexity as they have: some of their

characteristics are usually devoid of meaning. Thus it may well

be possible to extract in words all that has meaning in an

image-content; in that case the word-content and the

image-content will have exactly the same objective reference.

The content of a belief, when expressed in words, is the same

thing (or very nearly the same thing) as what in logic is called

a "proposition." A proposition is a series of words (or sometimes

a single word) expressing the kind of thing that can be asserted

or denied. "That all men are mortal," "that Columbus discovered

America," "that Charles I died in his bed," "that all

philosophers are wise," are propositions. Not any series of words

is a proposition, but only such series of words as have

"meaning," or, in our phraseology, "objective reference." Given

the meanings of separate words, and the rules of syntax, the

meaning of a proposition is determinate. This is the reason why

we can understand a sentence we never heard before. You probably

never heard before the proposition "that the inhabitants of the

Andaman Islands habitually eat stewed hippopotamus for dinner,"

but there is no difficulty in understanding the proposition. The

question of the relation between the meaning of a sentence and

the meanings of the separate words is difficult, and I shall not

pursue it now; I brought it up solely as being illustrative of

the nature of propositions.

We may extend the term "proposition" so as to cover the

image-contents of beliefs consisting of images. Thus, in the case

of remembering a room in which the window is to the left of the

door, when we believe the image-content the proposition will

consist of the image of the window on the left together with the

image of the door on the right. We will distinguish propositions

of this kind as "image-propositions" and propositions in words as

"word-propositions." We may identify propositions in general with

the contents of actual and possible beliefs, and we may say that

it is propositions that are true or false. In logic we are

concerned with propositions rather than beliefs, since logic is

not interested in what people do in fact believe, but only in the

conditions which determine the truth or falsehood of possible

beliefs. Whenever possible, except when actual beliefs are in

question, it is generally a simplification to deal with


It would seem that image-propositions are more primitive than

word-propositions, and may well ante-date language. There is no

reason why memory-images, accompanied by that very simple

belief-feeling which we decided to be the essence of memory,

should not have occurred before language arose; indeed, it would

be rash to assert positively that memory of this sort does not

occur among the higher animals. Our more elementary beliefs,

notably those that are added to sensation to make perception,

often remain at the level of images. For example, most of the

visual objects in our neighbourhood rouse tactile images: we have

a different feeling in looking at a sofa from what we have in

looking at a block of marble, and the difference consists chiefly

in different stimulation of our tactile imagination. It may be

said that the tactile images are merely present, without any

accompanying belief; but I think this view, though sometimes

correct, derives its plausibility as a general proposition from

our thinking of explicit conscious belief only. Most of our

beliefs, like most of our wishes, are "unconscious," in the sense

that we have never told ourselves that we have them. Such beliefs

display themselves when the expectations that they arouse fail in

any way. For example, if someone puts tea (without milk) into a

glass, and you drink it under the impression that it is going to

be beer; or if you walk on what appears to be a tiled floor, and

it turns out to be a soft carpet made to look like tiles. The

shock of surprise on an occasion of this kind makes us aware of

the expectations that habitually enter into our perceptions; and

such expectations must be classed as beliefs, in spite of the

fact that we do not normally take note of them or put them into

words. I remember once watching a cock pigeon running over and

over again to the edge of a looking-glass to try to wreak

vengeance on the particularly obnoxious bird whom he expected to

find there, judging by what he saw in the glass. He must have

experienced each time the sort of surprise on finding nothing,

which is calculated to lead in time to the adoption of Berkeley's

theory that objects of sense are only in the mind. His

expectation, though not expressed in words, deserved, I think, to

be called a belief.

I come now to the question what constitutes believing, as opposed

to the content believed.

To begin with, there are various different attitudes that may be

taken towards the same content. Let us suppose, for the sake of

argument, that you have a visual image of your breakfast-table.

You may expect it while you are dressing in the morning; remember

it as you go to your work; feel doubt as to its correctness when

questioned as to your powers of visualizing; merely entertain the

image, without connecting it with anything external, when you are

going to sleep; desire it if you are hungry, or feel aversion for

it if you are ill. Suppose, for the sake of definiteness, that

the content is "an egg for breakfast." Then you have the

following attitudes "I expect there will be an egg for

breakfast"; "I remember there was an egg for breakfast"; "Was

there an egg for breakfast?" "An egg for breakfast: well, what of

it?" "I hope there will be an egg for breakfast"; "I am afraid

there will be an egg for breakfast and it is sure to be bad." I

do not suggest that this is a list of all possible attitudes on

the subject; I say only that they are different attitudes, all

concerned with the one content "an egg for breakfast."

These attitudes are not all equally ultimate. Those that involve

desire and aversion have occupied us in Lecture III. For the

present, we are only concerned with such as are cognitive. In

speaking of memory, we distinguished three kinds of belief

directed towards the same content, namely memory, expectation and

bare assent without any time-determination in the belief-feeling.

But before developing this view, we must examine two other

theories which might be held concerning belief, and which, in

some ways, would be more in harmony with a behaviourist outlook

than the theory I wish to advocate.

(1) The first theory to be examined is the view that the

differentia of belief consists in its causal efficacy I do not

wish to make any author responsible for this theory: I wish

merely to develop it hypothetically so that we may judge of its


We defined the meaning of an image or word by causal efficacy,

namely by associations: an image or word acquires meaning, we

said, through having the same associations as what it means.

We propose hypothetically to define "belief" by a different kind

of causal efficacy, namely efficacy in causing voluntary

movements. (Voluntary movements are defined as those vital

movements which are distinguished from reflex movements as

involving the higher nervous centres. I do not like to

distinguish them by means of such notions as "consciousness" or

"will," because I do not think these notions, in any definable

sense, are always applicable. Moreover, the purpose of the theory

we are examining is to be, as far as possible, physiological and

behaviourist, and this purpose is not achieved if we introduce

such a conception as "consciousness" or "will." Nevertheless, it

is necessary for our purpose to find some way of distinguishing

between voluntary and reflex movements, since the results would

be too paradoxical, if we were to say that reflex movements also

involve beliefs.) According to this definition, a content is said

to be "believed" when it causes us to move. The images aroused

are the same if you say to me, "Suppose there were an escaped

tiger coming along the street," and if you say to me, "There is

an escaped tiger coming along the street." But my actions will be

very different in the two cases: in the first, I shall remain

calm; in the second, it is possible that I may not. It is

suggested, by the theory we are considering, that this difference

of effects constitutes what is meant by saying that in the second

case I believe the proposition suggested, while in the first case

I do not. According to this view, images or words are "believed"

when they cause bodily movements.

I do not think this theory is adequate, but I think it is

suggestive of truth, and not so easily refutable as it might

appear to be at first sight.

It might be objected to the theory that many things which we

certainly believe do not call for any bodily movements. I believe

that Great Britain is an island, that whales are mammals, that

Charles I was executed, and so on; and at first sight it seems

obvious that such beliefs, as a rule, do not call for any action

on my part. But when we investigate the matter more closely, it

becomes more doubtful. To begin with, we must distinguish belief

as a mere DISPOSITION from actual active belief. We speak as if

we always believed that Charles I was executed, but that only

means that we are always ready to believe it when the subject

comes up. The phenomenon we are concerned to analyse is the

active belief, not the permanent disposition. Now, what are the

occasions when, we actively believe that Charles I was executed?

Primarily: examinations, when we perform the bodily movement of

writing it down; conversation, when we assert it to display our

historical erudition; and political discourses, when we are

engaged in showing what Soviet government leads to. In all these

cases bodily movements (writing or speaking) result from our


But there remains the belief which merely occurs in "thinking."

One may set to work to recall some piece of history one has been

reading, and what one recalls is believed, although it probably

does not cause any bodily movement whatever. It is true that what

we believe always MAY influence action. Suppose I am invited to

become King of Georgia: I find the prospect attractive, and go to

Cook's to buy a third-class ticket to my new realm. At the last

moment I remember Charles I and all the other monarchs who have

come to a bad end; I change my mind, and walk out without

completing the transaction. But such incidents are rare, and

cannot constitute the whole of my belief that Charles I was

executed. The conclusion seems to be that, although a belief

always MAY influence action if it becomes relevant to a practical

issue, it often exists actively (not as a mere disposition)

without producing any voluntary movement whatever. If this is

true, we cannot define belief by the effect on voluntary


There is another, more theoretical, ground for rejecting the view

we are examining. It is clear that a proposition can be either

believed or merely considered, and that the content is the same

in both cases. We can expect an egg for breakfast, or merely

entertain the supposition that there may be an egg for breakfast.

A moment ago I considered the possibility of being invited to

become King of Georgia, but I do not believe that this will

happen. Now, it seems clear that, since believing and considering

have different effects if one produces bodily movements while the

other does not, there must be some intrinsic difference between

believing and considering*; for if they were precisely similar,

their effects also would be precisely similar. We have seen that

the difference between believing a given proposition and merely

considering it does not lie in the content; therefore there must

be, in one case or in both, something additional to the content

which distinguishes the occurrence of a belief from the

occurrence of a mere consideration of the same content. So far as

the theoretical argument goes, this additional element may exist

only in belief, or only in consideration, or there may be one

sort of additional element in the case of belief, and another in

the case of consideration. This brings us to the second view

which we have to examine.

* Cf. Brentano, "Psychologie vom empirischen Standpunkte," p. 268

(criticizing Bain, "The Emotions and the Will").

(1) The theory which we have now to consider regards belief as

belonging to every idea which is entertained, except in so far as

some positive counteracting force interferes. In this view belief

is not a positive phenomenon, though doubt and disbelief are so.

What we call belief, according to this hypothesis, involves only

the appropriate content, which will have the effects

characteristic of belief unless something else operating

simultaneously inhibits them. James (Psychology, vol. ii, p. 288)

quotes with approval, though inaccurately, a passage from Spinoza

embodying this view:

"Let us conceive a boy imagining to himself a horse, and taking

note of nothing else. As this imagination involves the existence


EXISTENCE [James's italics], he will necessarily contemplate the

horse as present, nor will he be able to doubt of its existence,

however little certain of it he may be. I deny that a man in so

far as he imagines [percipit] affirms nothing. For what is it to

imagine a winged horse but to affirm that the horse [that horse,

namely] has wings? For if the mind had nothing before it but the

winged horse, it would contemplate the same as present, would

have no cause to doubt of its existence, nor any power of

dissenting from its existence, unless the imagination of the

winged horse were joined to an idea which contradicted [tollit]

its existence" ("Ethics," vol. ii, p. 49, Scholium).

To this doctrine James entirely assents, adding in italics:



If this view is correct, it follows (though James does not draw

the inference) that there is no need of any specific feeling

called "belief," and that the mere existence of images yields all

that is required. The state of mind in which we merely consider a

proposition, without believing or disbelieving it, will then

appear as a sophisticated product, the result of some rival force

adding to the image-proposition a positive feeling which may be

called suspense or non-belief--a feeling which may be compared to

that of a man about to run a race waiting for the signal. Such a

man, though not moving, is in a very different condition from

that of a man quietly at rest And so the man who is considering a

proposition without believing it will be in a state of tension,

restraining the natural tendency to act upon the proposition

which he would display if nothing interfered. In this view belief

primarily consists merely in the existence of the appropriate

images without any counteracting forces.

There is a great deal to be said in favour of this view, and I

have some hesitation in regarding it as inadequate. It fits

admirably with the phenomena of dreams and hallucinatory images,

and it is recommended by the way in which it accords with mental

development. Doubt, suspense of judgment and disbelief all seem

later and more complex than a wholly unreflecting assent. Belief

as a positive phenomenon, if it exists, may be regarded, in this

view, as a product of doubt, a decision after debate, an

acceptance, not merely of THIS, but of THIS-RATHER-THAN-THAT. It

is not difficult to suppose that a dog has images (possible

olfactory) of his absent master, or of the rabbit that he dreams

of hunting. But it is very difficult to suppose that he can

entertain mere imagination-images to which no assent is given.

I think it must be conceded that a mere image, without the

addition of any positive feeling that could be called "belief,"

is apt to have a certain dynamic power, and in this sense an

uncombated image has the force of a belief. But although this may

be true, it accounts only for some of the simplest phenomena in

the region of belief. It will not, for example, explain memory.

Nor can it explain beliefs which do not issue in any proximate

action, such as those of mathematics. I conclude, therefore, that

there must be belief-feelings of the same order as those of doubt

or disbelief, although phenomena closely analogous to those of

belief can be produced by mere uncontradicted images.

(3) I come now to the view of belief which I wish to advocate. It

seems to me that there are at least three kinds of belief, namely

memory, expectation and bare assent. Each of these I regard as

constituted by a certain feeling or complex of sensations,

attached to the content believed. We may illustrate by an

example. Suppose I am believing, by means of images, not words,

that it will rain. We have here two interrelated elements, namely

the content and the expectation. The content consists of images

of (say) the visual appearance of rain, the feeling of wetness,

the patter of drops, interrelated, roughly, as the sensations

would be if it were raining. Thus the content is a complex fact

composed of images. Exactly the same content may enter into the

memory "it was raining" or the assent "rain occurs." The

difference of these cases from each other and from expectation

does not lie in the content. The difference lies in the nature of

the belief-feeling. I, personally, do not profess to be able to

analyse the sensations constituting respectively memory,

expectation and assent; but I am not prepared to say that they

cannot be analysed. There may be other belief-feelings, for

example in disjunction and implication; also a disbelief-feeling.

It is not enough that the content and the belief-feeling should

coexist: it is necessary that there should be a specific relation

between them, of the sort expressed by saying that the content is

what is believed. If this were not obvious, it could be made

plain by an argument. If the mere co-existence of the content and

the belief-feeling sufficed, whenever we were having (say) a

memory-feeling we should be remembering any proposition which

came into our minds at the same time. But this is not the case,

since we may simultaneously remember one proposition and merely

consider another.

We may sum up our analysis, in the case of bare assent to a

proposition not expressed in words, as follows: (a) We have a

proposition, consisting of interrelated images, and possibly

partly of sensations; (b) we have the feeling of assent, which is

presumably a complex sensation demanding analysis; (c) we have a

relation, actually subsisting, between the assent and the

proposition, such as is expressed by saying that the proposition

in question is what is assented to. For other forms of

belief-feeling or of content, we have only to make the necessary

substitutions in this analysis.

If we are right in our analysis of belief, the use of words in

expressing beliefs is apt to be misleading. There is no way of

distinguishing, in words, between a memory and an assent to a

proposition about the past: "I ate my breakfast" and "Caesar

conquered Gaul" have the same verbal form, though (assuming that

I remember my breakfast) they express occurrences which are

psychologically very different. In the one case, what happens is

that I remember the content "eating my breakfast"; in the other

case, I assent to the content "Caesar's conquest of Gaul

occurred." In the latter case, but not in the former, the

pastness is part of the content believed. Exactly similar remarks

apply to the difference between expectation, such as we have when

waiting for the thunder after a flash of lightning, and assent to

a proposition about the future, such as we have in all the usual

cases of inferential knowledge as to what will occur. I think

this difficulty in the verbal expression of the temporal aspects

of beliefs is one among the causes which have hampered philosophy

in the consideration of time.

The view of belief which I have been advocating contains little

that is novel except the distinction of kinds of belief-feeling~

such as memory and expectation. Thus James says: "Everyone knows

the difference between imagining a thing and believing in its

existence, between supposing a proposition and acquiescing in its



ELSE" ("Psychology," vol. ii, p. 283. James's italics). He

proceeds to point out that drunkenness, and, still more, nitrous-

oxide intoxication, will heighten the sense of belief: in the

latter case, he says, a man's very soul may sweat with

conviction, and he be all the time utterly unable to say what he

is convinced of. It would seem that, in such cases, the feeling

of belief exists unattached, without its usual relation to a

content believed, just as the feeling of familiarity may

sometimes occur without being related to any definite familiar

object. The feeling of belief, when it occurs in this separated

heightened form, generally leads us to look for a content to

which to attach it. Much of what passes for revelation or mystic

insight probably comes in this way: the belief-feeling, in

abnormal strength, attaches itself, more or less accidentally, to

some content which we happen to think of at the appropriate

moment. But this is only a speculation, upon which I do not wish

to lay too much stress.


The definition of truth and falsehood, which is our topic to-day,

lies strictly outside our general subject, namely the analysis of

mind. From the psychological standpoint, there may be different

kinds of belief, and different degrees of certainty, but there

cannot be any purely psychological means of distinguishing

between true and false beliefs. A belief is rendered true or

false by relation to a fact, which may lie outside the experience

of the person entertaining the belief. Truth and falsehood,

except in the case of beliefs about our own minds, depend upon

the relations of mental occurrences to outside things, and thus

take us beyond the analysis of mental occurrences as they are in

themselves. Nevertheless, we can hardly avoid the consideration

of truth and falsehood. We wish to believe that our beliefs,

sometimes at least, yield KNOWLEDGE, and a belief does not yield

knowledge unless it is true. The question whether our minds are

instruments of knowledge, and, if so, in what sense, is so vital

that any suggested analysis of mind must be examined in relation

to this question. To ignore this question would be like

describing a chronometer without regard to its accuracy as a

time-keeper, or a thermometer without mentioning the fact that it

measures temperature.

Many difficult questions arise in connection with knowledge. It

is difficult to define knowledge, difficult to decide whether we

have any knowledge, and difficult, even if it is conceded that we

sometimes have knowledge to discover whether we can ever know

that we have knowledge in this or that particular case. I shall

divide the discussion into four parts:

I. We may regard knowledge, from a behaviourist standpoint, as

exhibited in a certain kind of response to the environment. This

response must have some characteristics which it shares with

those of scientific instruments, but must also have others that

are peculiar to knowledge. We shall find that this point of view

is important, but not exhaustive of the nature of knowledge.

II. We may hold that the beliefs that constitute knowledge are

distinguished from such as are erroneous or uncertain by

properties which are intrinsic either to single beliefs or to

systems of beliefs, being in either case discoverable without

reference to outside fact. Views of this kind have been widely

held among philosophers, but we shall find no reason to accept


III. We believe that some beliefs are true, and some false. This

raises the problem of VERIFIABILITY: are there any circumstances

which can justifiably give us an unusual degree of certainty that

such and such a belief is true? It is obvious that there are

circumstances which in fact cause a certainty of this sort, and

we wish to learn what we can from examining these circumstances.

IV. Finally, there is the formal problem of defining truth and

falsehood, and deriving the objective reference of a proposition

from the meanings of its component words.

We will consider these four problems in succession.

I. We may regard a human being as an instrument, which makes

various responses to various stimuli. If we observe these

responses from outside, we shall regard them as showing knowledge

when they display two characteristics, ACCURACY and

APPROPRIATENESS. These two are quite distinct, and even sometimes

incompatible. If I am being pursued by a tiger, accuracy is

furthered by turning round to look at him, but appropriateness by

running away without making any search for further knowledge of

the beast. I shall return to the question of appropriateness

later; for the present it is accuracy that I wish to consider.

When we are viewing a man from the outside, it is not his

beliefs, but his bodily movements, that we can observe. His

knowledge must be inferred from his bodily movements, and

especially from what he says and writes. For the present we may

ignore beliefs, and regard a man's knowledge as actually

consisting in what he says and does. That is to say, we will

construct, as far as possible, a purely behaviouristic account of

truth and falsehood.

If you ask a boy "What is twice two?" and the boy says "four,"

you take that as prima facie evidence that the boy knows what

twice two is. But if you go on to ask what is twice three, twice

four, twice five, and so on, and the boy always answers "four,"

you come to the conclusion that he knows nothing about it.

Exactly similar remarks apply to scientific instruments. I know a

certain weather-cock which has the pessimistic habit of always

pointing to the north-east. If you were to see it first on a cold

March day, you would think it an excellent weather-cock; but with

the first warm day of spring your confidence would be shaken. The

boy and the weather-cock have the same defect: they do not vary

their response when the stimulus is varied. A good instrument, or

a person with much knowledge, will give different responses to

stimuli which differ in relevant ways. This is the first point in

defining accuracy of response.

We will now assume another boy, who also, when you first question

him, asserts that twice two is four. But with this boy, instead

of asking him different questions, you make a practice of asking

him the same question every day at breakfast. You find that he

says five, or six, or seven, or any other number at random, and

you conclude that he also does not know what twice two is, though

by good luck he answered right the first time. This boy is like a

weather-cock which, instead of being stuck fast, is always going

round and round, changing without any change of wind. This boy

and weather-cock have the opposite defect to that of the previous

pair: they give different responses to stimuli which do not

differ in any relevant way.

In connection with vagueness in memory, we already had occasion

to consider the definition of accuracy. Omitting some of the

niceties of our previous discussion, we may say that an

instrument is ACCURATE when it avoids the defects of the two boys

and weather-cocks, that is to say, when--

(a) It gives different responses to stimuli which differ in

relevant ways;

(b) It gives the same response to stimuli which do not differ in

relevant ways.

What are relevant ways depends upon the nature and purpose of the

instrument. In the case of a weather-cock, the direction of the

wind is relevant, but not its strength; in the case of the boy,

the meaning of the words of your question is relevant, but not

the loudness of your voice, or whether you are his father or his

schoolmaster If, however, you were a boy of his own age, that

would be relevant, and the appropriate response would be


It is clear that knowledge is displayed by accuracy of response

to certain kinds of stimuli, e.g. examinations. Can we say,

conversely, that it consists wholly of such accuracy of response?

I do not think we can; but we can go a certain distance in this

direction. For this purpose we must define more carefully the

kind of accuracy and the kind of response that may be expected

where there is knowledge.

From our present point of view, it is difficult to exclude

perception from knowledge; at any rate, knowledge is displayed by

actions based upon perception. A bird flying among trees avoids

bumping into their branches; its avoidance is a response to

visual sensations. This response has the characteristic of

accuracy, in the main, and leads us to say that the bird "knows,"

by sight, what objects are in its neighbourhood. For a

behaviourist, this must certainly count as knowledge, however it

may be viewed by analytic psychology. In this case, what is

known, roughly, is the stimulus; but in more advanced knowledge

the stimulus and what is known become different. For example, you

look in your calendar and find that Easter will be early next

year. Here the stimulus is the calendar, whereas the response

concerns the future. Even this can be paralleled among

instruments: the behaviour of the barometer has a present

stimulus but foretells the future, so that the barometer might be

said, in a sense, to know the future. However that may be, the

point I am emphasizing as regards knowledge is that what is known

may be quite different from the stimulus, and no part of the

cause of the knowledge-response. It is only in sense-knowledge

that the stimulus and what is known are, with qualifications,

identifiable. In knowledge of the future, it is obvious that they

are totally distinct, since otherwise the response would precede

the stimulus. In abstract knowledge also they are distinct, since

abstract facts have no date. In knowledge of the past there are

complications, which we must briefly examine.

Every form of memory will be, from our present point of view, in

one sense a delayed response. But this phrase does not quite

clearly express what is meant. If you light a fuse and connect it

with a heap of dynamite, the explosion of the dynamite may be

spoken of, in a sense, as a delayed response to your lighting of

the fuse. But that only means that it is a somewhat late portion

of a continuous process of which the earlier parts have less

emotional interest. This is not the case with habit. A display of

habit has two sorts of causes: (a) the past occurrences which

generated the habit, (b) the present occurrence which brings it

into play. When you drop a weight on your toe, and say what you

do say, the habit has been caused by imitation of your

undesirable associates, whereas it is brought into play by the

dropping of the weight. The great bulk of our knowledge is a

habit in this sense: whenever I am asked when I was born, I reply

correctly by mere habit. It would hardly be correct to say that

getting born was the stimulus, and that my reply is a delayed

response But in cases of memory this way of speaking would have

an element of truth. In an habitual memory, the event remembered

was clearly an essential part of the stimulus to the formation of

the habit. The present stimulus which brings the habit into play

produces a different response from that which it would produce if

the habit did not exist. Therefore the habit enters into the

causation of the response, and so do, at one remove, the causes

of the habit. It follows that an event remembered is an essential

part of the causes of our remembering.

In spite, however, of the fact that what is known is SOMETIMES an

indispensable part of the cause of the knowledge, this

circumstance is, I think, irrelevant to the general question with

which we are concerned, namely What sort of response to what sort

of stimulus can be regarded as displaying knowledge? There is one

characteristic which the response must have, namely, it must

consist of voluntary movements. The need of this characteristic

is connected with the characteristic of APPROPRIATENESS, which I

do not wish to consider as yet. For the present I wish only to

obtain a clearer idea of the sort of ACCURACY that a

knowledge-response must have. It is clear from many instances

that accuracy, in other cases, may be purely mechanical. The most

complete form of accuracy consists in giving correct answers to

questions, an achievement in which calculating machines far

surpass human beings. In asking a question of a calculating

machine, you must use its language: you must not address it in

English, any more than you would address an Englishman in

Chinese. But if you address it in the language it understands. it

will tell you what is 34521 times 19987, without a moment's

hesitation or a hint of inaccuracy. We do not say the machine

KNOWS the answer, because it has no purpose of its own in giving

the answer: it does not wish to impress you with its cleverness,

or feel proud of being such a good machine. But as far as mere

accuracy goes, the machine leaves nothing to be desired.

Accuracy of response is a perfectly clear notion in the case of

answers to questions, but in other cases it is much more obscure.

We may say generally that an object whether animate or inanimate,

is "sensitive" to a certain feature of the environment if it

behaves differently according to the presence or absence of that

feature. Thus iron is sensitive to anything magnetic. But

sensitiveness does not constitute knowledge, and knowledge of a

fact which is not sensible is not sensitiveness to that fact, as

we have seen in distinguishing the fact known from the stimulus.

As soon as we pass beyond the simple case of question and answer,

the definition of knowledge by means of behaviour demands the

consideration of purpose. A carrier pigeon flies home, and so we

say it "knows" the way. But if it merely flew to some place at

random, we should not say that it "knew" the way to that place,

any more than a stone rolling down hill knows the way to the


On the features which distinguish knowledge from accuracy of

response in general, not much can be said from a behaviourist

point of view without referring to purpose. But the necessity of

SOMETHING besides accuracy of response may be brought out by the

following consideration: Suppose two persons, of whom one

believed whatever the other disbelieved, and disbelieved whatever

the other believed. So far as accuracy and sensitiveness of

response alone are concerned, there would be nothing to choose

between these two persons. A thermometer which went down for warm

weather and up for cold might be just as accurate as the usual

kind; and a person who always believes falsely is just as

sensitive an instrument as a person who always believes truly.

The observable and practical difference between them would be

that the one who always believed falsely would quickly come to a

bad end. This illustrates once more that accuracy of response to

stimulus does not alone show knowledge, but must be reinforced by

appropriateness, i.e. suitability for realizing one's purpose.

This applies even in the apparently simple case of answering

questions: if the purpose of the answers is to deceive, their

falsehood, not their truth, will be evidence of knowledge. The

proportion of the combination of appropriateness with accuracy in

the definition of knowledge is difficult; it seems that both

enter in, but that appropriateness is only required as regards

the general type of response, not as regards each individual


II. I have so far assumed as unquestionable the view that the

truth or falsehood of a belief consists in a relation to a

certain fact, namely the objective of the belief. This view has,

however, been often questioned. Philosophers have sought some

intrinsic criterion by which true and false beliefs could be

distinguished.* I am afraid their chief reason for this search

has been the wish to feel more certainty than seems otherwise

possible as to what is true and what is false. If we could

discover the truth of a belief by examining its intrinsic

characteristics, or those of some collection of beliefs of which

it forms part, the pursuit of truth, it is thought, would be a

less arduous business than it otherwise appears to be. But the

attempts which have been made in this direction are not

encouraging. I will take two criteria which have been suggested,

namely, (1) self-evidence, (2) mutual coherence. If we can show

that these are inadequate, we may feel fairly certain that no

intrinsic criterion hitherto suggested will suffice to

distinguish true from false beliefs.

* The view that such a criterion exists is generally held by

those whose views are in any degree derived from Hegel. It may be

illustrated by the following passage from Lossky, "The Intuitive

Basis of Knowledge" (Macmillan, 1919), p. 268: "Strictly

speaking, a false judgment is not a judgment at all. The

predicate does not follow from the subject S alone, but from the

subject plus a certain addition C, WHICH IN NO SENSE BELONGS TO

THE CONTENT OF THE JUDGMENT. What takes place may be a process of

association of ideas, of imagining, or the like, but is not a

process of judging. An experienced psychologist will be able by

careful observation to detect that in this process there is

wanting just the specific element of the objective dependence of

the predicate upon the subject which is characteristic of a

judgment. It must be admitted, however, that an exceptional power

of observation is needed in order to distinguish, by means of

introspection, mere combination of ideas from judgments."

(1) Self-evidence.--Some of our beliefs seem to be peculiarly

indubitable. One might instance the belief that two and two are

four, that two things cannot be in the same place at the same

time, nor one thing in two places, or that a particular buttercup

that we are seeing is yellow. The suggestion we are to examine is

that such: beliefs have some recognizable quality which secures

their truth, and the truth of whatever is deduced from them

according to self-evident principles of inference. This theory is

set forth, for example, by Meinong in his book, "Ueber die

Erfahrungsgrundlagen unseres Wissens."

If this theory is to be logically tenable, self-evidence must not

consist merely in the fact that we believe a proposition. We

believe that our beliefs are sometimes erroneous, and we wish to

be able to select a certain class of beliefs which are never

erroneous. If we are to do this, it must be by some mark which

belongs only to certain beliefs, not to all; and among those to

which it belongs there must be none that are mutually

inconsistent. If, for example, two propositions p and q were

self-evident, and it were also self-evident that p and q could

not both be true, that would condemn self-evidence as a guarantee

of truth. Again, self-evidence must not be the same thing as the

absence of doubt or the presence of complete certainty. If we are

completely certain of a proposition, we do not seek a ground to

support our belief. If self-evidence is alleged as a ground of

belief, that implies that doubt has crept in, and that our

self-evident proposition has not wholly resisted the assaults of

scepticism. To say that any given person believes some things so

firmly that he cannot be made to doubt them is no doubt true.

Such beliefs he will be willing to use as premisses in reasoning,

and to him personally they will seem to have as much evidence as

any belief can need. But among the propositions which one man

finds indubitable there will be some that another man finds it

quite possible to doubt. It used to seem self-evident that there

could not be men at the Antipodes, because they would fall off,

or at best grow giddy from standing on their heads. But New

Zealanders find the falsehood of this proposition self-evident.

Therefore, if self-evidence is a guarantee of truth, our

ancestors must have been mistaken in thinking their beliefs about

the Antipodes self-evident. Meinong meets this difficulty by

saying that some beliefs are falsely thought to be self-evident,

but in the case of others it is self-evident that they are

self-evident, and these are wholly reliable. Even this, however,

does not remove the practical risk of error, since we may

mistakenly believe it self-evident that a certain belief is

self-evident. To remove all risk of error, we shall need an

endless series of more and more complicated self-evident beliefs,

which cannot possibly be realized in practice. It would seem,

therefore, that self-evidence is useless as a practical criterion

for insuring truth.

The same result follows from examining instances. If we take the

four instances mentioned at the beginning of this discussion, we

shall find that three of them are logical, while the fourth is a

judgment of perception. The proposition that two and two are four

follows by purely logical deduction from definitions: that means

that its truth results, not from the properties of objects, but

from the meanings of symbols. Now symbols, in mathematics, mean

what we choose; thus the feeling of self-evidence, in this case,

seems explicable by the fact that the whole matter is within our

control. I do not wish to assert that this is the whole truth

about mathematical propositions, for the question is complicated,

and I do not know what the whole truth is. But I do wish to

suggest that the feeling of self-evidence in mathematical

propositions has to do with the fact that they are concerned with

the meanings of symbols, not with properties of the world such as

external observation might reveal.

Similar considerations apply to the impossibility of a thing

being in two places at once, or of two things being in one place

at the same time. These impossibilities result logically, if I am

not mistaken, from the definitions of one thing and one place.

That is to say, they are not laws of physics, but only part of

the intellectual apparatus which we have manufactured for

manipulating physics. Their self-evidence, if this is so, lies

merely in the fact that they represent our decision as to the use

of words, not a property of physical objects.

Judgments of perception, such as "this buttercup is yellow," are

in a quite different position from judgments of logic, and their

self-evidence must have a different explanation. In order to

arrive at the nucleus of such a judgment, we will eliminate, as

far as possible, the use of words which take us beyond the

present fact, such as "buttercup" and "yellow." The simplest kind

of judgment underlying the perception that a buttercup is yellow

would seem to be the perception of similarity in two colours seen

simultaneously. Suppose we are seeing two buttercups, and we

perceive that their colours are similar. This similarity is a

physical fact, not a matter of symbols or words; and it certainly

seems to be indubitable in a way that many judgments are not.

The first thing to observe, in regard to such judgments, is that

as they stand they are vague. The word "similar" is a vague word,

since there are degrees of similarity, and no one can say where

similarity ends and dissimilarity begins. It is unlikely that our

two buttercups have EXACTLY the same colour, and if we judged

that they had we should have passed altogether outside the region

of self-evidence. To make our proposition more precise, let us

suppose that we are also seeing a red rose at the same time. Then

we may judge that the colours of the buttercups are more similar

to each other than to the colour of the rose. This judgment seems

more complicated, but has certainly gained in precision. Even

now, however, it falls short of complete precision, since

similarity is not prima facie measurable, and it would require

much discussion to decide what we mean by greater or less

similarity. To this process of the pursuit of precision there is

strictly no limit.

The next thing to observe (although I do not personally doubt

that most of our judgments of perception are true) is that it is

very difficult to define any class of such judgments which can be

known, by its intrinsic quality, to be always exempt from error.

Most of our judgments of perception involve correlations, as when

we judge that a certain noise is that of a passing cart. Such

judgments are all obviously liable to error, since there is no

correlation of which we have a right to be certain that it is

invariable. Other judgments of perception are derived from

recognition, as when we say "this is a buttercup," or even merely

"this is yellow." All such judgments entail some risk of error,

though sometimes perhaps a very small one; some flowers that look

like buttercups are marigolds, and colours that some would call

yellow others might call orange. Our subjective certainty is

usually a result of habit, and may lead us astray in

circumstances which are unusual in ways of which we are unaware.

For such reasons, no form of self-evidence seems to afford an

absolute criterion of truth. Nevertheless, it is perhaps true

that judgments having a high degree of subjective certainty are

more apt to be true than other judgments. But if this be the

case, it is a result to be demonstrated, not a premiss from which

to start in defining truth and falsehood. As an initial

guarantee, therefore, neither self-evidence nor subjective

certainty can be accepted as adequate.

(2) Coherence.--Coherence as the definition of truth is advocated

by idealists, particularly by those who in the main follow Hegel.

It is set forth ably in Mr. Joachim's book, "The Nature of Truth"

(Oxford, 1906). According to this view, any set of propositions

other than the whole of truth can be condemned on purely logical

grounds, as internally inconsistent; a single proposition, if it

is what we should ordinarily call false, contradicts itself

irremediably, while if it is what we should ordinarily call true,

it has implications which compel us to admit other propositions,

which in turn lead to others, and so on, until we find ourselves

committed to the whole of truth. One might illustrate by a very

simple example: if I say "so-and-so is a married man," that is

not a self-subsistent proposition. We cannot logically conceive

of a universe in which this proposition constituted the whole of

truth. There must be also someone who is a married woman, and who

is married to the particular man in question. The view we are

considering regards everything that can be said about any one

object as relative in the same sort of way as "so-and-so is a

married man." But everything, according to this view, is

relative, not to one or two other things, but to all other

things, so that from one bit of truth the whole can be inferred.

The fundamental objection to this view is logical, and consists

in a criticism of its doctrine as to relations. I shall omit this

line of argument, which I have developed elsewhere.* For the

moment I will content myself with saying that the powers of logic

seem to me very much less than this theory supposes. If it were

taken seriously, its advocates ought to profess that any one

truth is logically inferable from any other, and that, for

example, the fact that Caesar conquered Gaul, if adequately

considered, would enable us to discover what the weather will be

to-morrow. No such claim is put forward in practice, and the

necessity of empirical observation is not denied; but according

to the theory it ought to be.

* In the article on "The Monistic Theory of Truth" in

"Philosophical Essays" (Longmans, 1910), reprinted from the

"Proceedings of the Aristotelian Society," 1906-7.

Another objection is that no endeavour is made to show that we

cannot form a consistent whole composed partly or wholly of false

propositions, as in a novel. Leibniz's conception of many

possible worlds seems to accord much better with modern logic and

with the practical empiricism which is now universal. The attempt

to deduce the world by pure thought is attractive, and in former

times was largely supposed capable of success. But nowadays most

men admit that beliefs must be tested by observation, and not

merely by the fact that they harmonize with other beliefs. A

consistent fair-ytale is a different thing from truth, however

elaborate it may be. But to pursue this topic would lead us into

difficult technicalities; I shall therefore assume, without

further argument, that coherence is not sufficient as a

definition of truth.

III. Many difficult problems arise as regards the verifiability

of beliefs. We believe various things, and while we believe them

we think we know them. But it sometimes turns out that we were

mistaken, or at any rate we come to think we were. We must be

mistaken either in our previous opinion or in our subsequent

recantation; therefore our beliefs are not all correct, and there

are cases of belief which are not cases of knowledge. The

question of verifiability is in essence this: can we discover any

set of beliefs which are never mistaken or any test which, when

applicable, will always enable us to discriminate between true

and false beliefs? Put thus broadly and abstractly, the answer

must be negative. There is no way hitherto discovered of wholly

eliminating the risk of error, and no infallible criterion. If we

believe we have found a criterion, this belief itself may be

mistaken; we should be begging the question if we tried to test

the criterion by applying the criterion to itself.

But although the notion of an absolute criterion is chimerical,

there may be relative criteria, which increase the probability of

truth. Common sense and science hold that there are. Let us see

what they have to say.

One of the plainest cases of verification, perhaps ultimately the

only case, consists in the happening of something expected. You

go to the station believing that there will be a train at a

certain time; you find the train, you get into it, and it starts

at the expected time This constitutes verification, and is a

perfectly definite experience. It is, in a sense, the converse of

memory instead of having first sensations and then images

accompanied by belief, we have first images accompanied by belief

and then sensations. Apart from differences as to the time-order

and the accompanying feelings, the relation between image and

sensation is closely similar in the two cases of memory and

expectation; it is a relation of similarity, with difference as

to causal efficacy--broadly, the image has the psychological but

not the physical effects that the sensation would have. When an

image accompanied by an expectation-belief is thus succeeded by a

sensation which is the "meaning" of the image, we say that the

expectation-belief has been verified. The experience of

verification in this sense is exceedingly familiar; it happens

every time that accustomed activities have results that are not

surprising, in eating and walking and talking and all our daily


But although the experience in question is common, it is not

wholly easy to give a theoretical account of it. How do we know

that the sensation resembles the previous image? Does the image

persist in presence of the sensation, so that we can compare the

two? And even if SOME image does persist, how do we know that it

is the previous image unchanged? It does not seem as if this line

of inquiry offered much hope of a successful issue. It is better,

I think, to take a more external and causal view of the relation

of expectation to expected occurrence. If the occurrence, when it

comes, gives us the feeling of expectedness, and if the

expectation, beforehand, enabled us to act in a way which proves

appropriate to the occurrence, that must be held to constitute

the maximum of verification. We have first an expectation, then a

sensation with the feeling of expectedness related to memory of

the expectation. This whole experience, when it occurs, may be

defined as verification, and as constituting the truth of the

expectation. Appropriate action, during the period of

expectation, may be regarded as additional verification, but is

not essential. The whole process may be illustrated by looking up

a familiar quotation, finding it in the expected words, and in

the expected part of the book. In this case we can strengthen the

verification by writing down beforehand the words which we expect

to find.

I think all verification is ultimately of the above sort. We

verify a scientific hypothesis indirectly, by deducing

consequences as to the future, which subsequent experience

confirms. If somebody were to doubt whether Caesar had crossed

the Rubicon, verification could only be obtained from the future.

We could proceed to display manuscripts to our historical

sceptic, in which it was said that Caesar had behaved in this

way. We could advance arguments, verifiable by future experience,

to prove the antiquity of the manuscript from its texture,

colour, etc. We could find inscriptions agreeing with the

historian on other points, and tending to show his general

accuracy. The causal laws which our arguments would assume could

be verified by the future occurrence of events inferred by means

of them. The existence and persistence of causal laws, it is

true, must be regarded as a fortunate accident, and how long it

will continue we cannot tell. Meanwhile verification remains

often practically possible. And since it is sometimes possible,

we can gradually discover what kinds of beliefs tend to be

verified by experience, and what kinds tend to be falsified; to

the former kinds we give an increased degree of assent, to the

latter kinds a diminished degree. The process is not absolute or

infallible, but it has been found capable of sifting beliefs and

building up science. It affords no theoretical refutation of the

sceptic, whose position must remain logically unassailable; but

if complete scepticism is rejected, it gives the practical method

by which the system of our beliefs grows gradually towards the

unattainable ideal of impeccable knowledge.

IV. I come now to the purely formal definition of the truth or

falsehood of a belief. For this definition it is necessary first

of all to consider the derivation of the objective reference of a

proposition from the meanings of its component words or images.

Just as a word has meaning, so a proposition has an objective

reference. The objective reference of a proposition is a function

(in the mathematical sense) of the meanings of its component

words. But the objective reference differs from the meaning of a

word through the duality of truth and falsehood. You may believe

the proposition "to-day is Tuesday" both when, in fact, to-day is

Tuesday, and when to-day is not Tuesday. If to-day is not

Tuesday, this fact is the objective of your belief that to-day is

Tuesday. But obviously the relation of your belief to the fact is

different in this case from what it is in the case when to-day is

Tuesday. We may say, metaphorically, that when to-day is Tuesday,

your belief that it is Tuesday points TOWARDS the fact, whereas

when to-day is not Tuesday your belief points AWAY FROM the fact.

Thus the objective reference of a belief is not determined by the

fact alone, but by the direction of the belief towards or away

from the fact.* If, on a Tuesday, one man believes that it is

Tuesday while another believes that it is not Tuesday, their

beliefs have the same objective, namely the fact that it is

Tuesday but the true belief points towards the fact while the

false one points away from it. Thus, in order to define the

reference of a proposition we have to take account not only of

the objective, but also of the direction of pointing, towards the

objective in the case of a true proposition and away from it in

the case of a false one.

* I owe this way of looking at the matter to my friend Ludwig


This mode of stating the nature of the objective reference of a

proposition is necessitated by the circumstance that there are

true and false propositions, but not true and false facts. If

to-day is Tuesday, there is not a false objective "to-day is not

Tuesday," which could be the objective of the false belief

"to-day is not Tuesday." This is the reason why two beliefs which

are each other's contradictories have the same objective. There

is, however, a practical inconvenience, namely that we cannot

determine the objective reference of a proposition, according to

this definition, unless we know whether the proposition is true

or false. To avoid this inconvenience, it is better to adopt a

slightly different phraseology, and say: The "meaning" of the

proposition "to-day is Tuesday" consists in pointing to the fact

"to-day is Tuesday" if that is a fact, or away from the fact

"to-day is not Tuesday" if that is a fact. The "meaning" of the

proposition "to-day is not Tuesday" will be exactly the opposite.

By this hypothetical form we are able to speak of the meaning of

a proposition without knowing whether it is true or false.

According to this definition, we know the meaning of a

proposition when we know what would make it true and what would

make it false, even if we do not know whether it is in fact true

or false.

The meaning of a proposition is derivative from the meanings of

its constituent words. Propositions occur in pairs, distinguished

(in simple cases) by the absence or presence of the word "not."

Two such propositions have the same objective, but opposite

meanings: when one is true, the other is false, and when one is

false, the other is true.

The purely formal definition of truth and falsehood offers little

difficulty. What is required is a formal expression of the fact

that a proposition is true when it points towards its objective,

and false when it points away from it, In very simple cases we

can give a very simple account of this: we can say that true

propositions actually resemble their objectives in a way in which

false propositions do not. But for this purpose it is necessary

to revert to image-propositions instead of word-propositions. Let

us take again the illustration of a memory-image of a familiar

room, and let us suppose that in the image the window is to the

left of the door. If in fact the window is to the left of the

door, there is a correspondence between the image and the

objective; there is the same relation between the window and the

door as between the images of them. The image-memory consists of

the image of the window to the left of the image of the door.

When this is true, the very same relation relates the terms of

the objective (namely the window and the door) as relates the

images which mean them. In this case the correspondence which

constitutes truth is very simple.

In the case we have just been considering the objective consists

of two parts with a certain relation (that of left-to-right), and

the proposition consists of images of these parts with the very

same relation. The same proposition, if it were false, would have

a less simple formal relation to its objective. If the

image-proposition consists of an image of the window to the left

of an image of the door, while in fact the window is not to the

left of the door, the proposition does not result from the

objective by the mere substitution of images for their

prototypes. Thus in this unusually simple case we can say that a

true proposition "corresponds" to its objective in a formal sense

in which a false proposition does not. Perhaps it may be possible

to modify this notion of formal correspondence in such a way as

to be more widely applicable, but if so, the modifications

required will be by no means slight. The reasons for this must

now be considered.

To begin with, the simple type of correspondence we have been

exhibiting can hardly occur when words are substituted for

images, because, in word-propositions, relations are usually

expressed by words, which are not themselves relations. Take such

a proposition as "Socrates precedes Plato." Here the word

"precedes" is just as solid as the words "Socrates" and "Plato";

it MEANS a relation, but is not a relation. Thus the objective

which makes our proposition true consists of TWO terms with a

relation between them, whereas our proposition consists of THREE

terms with a relation of order between them. Of course, it would

be perfectly possible, theoretically, to indicate a few chosen

relations, not by words, but by relations between the other

words. "Socrates-Plato" might be used to mean "Socrates precedes

Plato"; "PlaSocrates-to" might be used to mean "Plato was born

before Socrates and died after him"; and so on. But the

possibilities of such a method would be very limited. For aught I

know, there may be languages that use it, but they are not among

the languages with which I am acquainted. And in any case, in

view of the multiplicity of relations that we wish to express, no

language could advance far without words for relations. But as

soon as we have words for relations, word-propositions have

necessarily more terms than the facts to which they refer, and

cannot therefore correspond so simply with their objectives as

some image-propositions can.

The consideration of negative propositions and negative facts

introduces further complications. An image-proposition is

necessarily positive: we can image the window to the left of the

door, or to the right of the door, but we can form no image of

the bare negative "the window not to the left of the door." We

can DISBELIEVE the image-proposition expressed by "the window to

the left of the door," and our disbelief will be true if the

window is not to the left of the door. But we can form no image

of the fact that the window is not to the left of the door.

Attempts have often been made to deny such negative facts, but,

for reasons which I have given elsewhere,* I believe these

attempts to be mistaken, and I shall assume that there are

negative facts.

* "Monist," January, 1919, p. 42 ff.

Word-propositions, like image-propositions, are always positive

facts. The fact that Socrates precedes Plato is symbolized in

English by the fact that the word "precedes" occurs between the

words "Socrates" and "Plato." But we cannot symbolize the fact

that Plato does not precede Socrates by not putting the word

"precedes" between "Plato" and "Socrates." A negative fact is not

sensible, and language, being intended for communication, has to

be sensible. Therefore we symbolize the fact that Plato does not

precede Socrates by putting the words "does not precede" between

"Plato" and "Socrates." We thus obtain a series of words which is

just as positive a fact as the series "Socrates precedes Plato."

The propositions asserting negative facts are themselves positive

facts; they are merely different positive facts from those

asserting positive facts.

We have thus, as regards the opposition of positive and negative,

three different sorts of duality, according as we are dealing

with facts, image-propositions, or word-propositions. We have,


(1) Positive and negative facts;

(2) Image-propositions, which may be believed or disbelieved, but

do not allow any duality of content corresponding to positive and

negative facts;

(3) Word-propositions, which are always positive facts, but are

of two kinds: one verified by a positive objective, the other by

a negative objective.

Owing to these complications, the simplest type of correspondence

is impossible when either negative facts or negative propositions

are involved.

Even when we confine ourselves to relations between two terms

which are both imaged, it may be impossible to form an

image-proposition in which the relation of the terms is

represented by the same relation of the images. Suppose we say

"Caesar was 2,000 years before Foch," we express a certain

temporal relation between Caesar and Foch; but we cannot allow

2,000 years to elapse between our image of Caesar and our image

of Foch. This is perhaps not a fair example, since "2,000 years

before" is not a direct relation. But take a case where the

relation is direct, say, "the sun is brighter than the moon." We

can form visual images of sunshine and moonshine, and it may

happen that our image of the sunshine is the brighter of the two,

but this is by no means either necessary or sufficient. The act

of comparison, implied in our judgment, is something more than

the mere coexistence of two images, one of which is in fact

brighter than the other. It would take us too far from our main

topic if we were to go into the question what actually occurs

when we make this judgment. Enough has been said to show that the

correspondence between the belief and its objective is more

complicated in this case than in that of the window to the left

of the door, and this was all that had to be proved.

In spite of these complications, the general nature of the formal

correspondence which makes truth is clear from our instances. In

the case of the simpler kind of propositions, namely those that I

call "atomic" propositions, where there is only one word

expressing a relation, the objective which would verify our

proposition, assuming that the word "not" is absent, is obtained

by replacing each word by what it means, the word meaning a

relation being replaced by this relation among the meanings of

the other words. For example, if the proposition is "Socrates

precedes Plato," the objective which verifies it results from

replacing the word "Socrates" by Socrates, the word "Plato" by

Plato, and the word "precedes" by the relation of preceding

between Socrates and Plato. If the result of this process is a

fact, the proposition is true; if not, it is false. When our

proposition is "Socrates does not precede Plato," the conditions

of truth and falsehood are exactly reversed. More complicated

propositions can be dealt with on the same lines. In fact, the

purely formal question, which has occupied us in this last

section, offers no very formidable difficulties.

I do not believe that the above formal theory is untrue, but I do

believe that it is inadequate. It does not, for example, throw

any light upon our preference for true beliefs rather than false

ones. This preference is only explicable by taking account of the

causal efficacy of beliefs, and of the greater appropriateness of

the responses resulting from true beliefs. But appropriateness

depends upon purpose, and purpose thus becomes a vital part of

theory of knowledge.


On the two subjects of the present lecture I have nothing

original to say, and I am treating them only in order to complete

the discussion of my main thesis, namely that all psychic

phenomena are built up out of sensations and images alone.

Emotions are traditionally regarded by psychologists as a

separate class of mental occurrences: I am, of course, not

concerned to deny the obvious fact that they have characteristics

which make a special investigation of them necessary. What I am

concerned with is the analysis of emotions. It is clear that an

emotion is essentially complex, and we have to inquire whether it

ever contains any non-physiological material not reducible to

sensations and images and their relations.

Although what specially concerns us is the analysis of emotions,

we shall find that the more important topic is the physiological

causation of emotions. This is a subject upon which much valuable

and exceedingly interesting work has been done, whereas the bare

analysis of emotions has proved somewhat barren. In view of the

fact that we have defined perceptions, sensations, and images by

their physiological causation, it is evident that our problem of

the analysis of the emotions is bound up with the problem of

their physiological causation.

Modern views on the causation of emotions begin with what is

called the James-Lange theory. James states this view in the

following terms ("Psychology," vol. ii, p. 449):

"Our natural way of thinking about these coarser emotions, grief,

fear, rage, love, is that the mental perception of some fact

excites the mental affection called the emotion, and that this

latter state of mind gives rise to the bodily expression. My

theory, on the contrary, is that THE BODILY CHANGES FOLLOW



(James's italics). Common sense says: we lose our fortune, are

sorry and weep; we meet a bear, are frightened and run; we are

insulted by a rival, are angry and strike. The hypothesis here to

be defended says that this order of sequence is incorrect, that

the one mental state is not immediately induced by the other,

that the bodily manifestations must first be interposed between,

and that the more rational statement is that we feel sorry

because we cry, angry because we strike, afraid because we

tremble, and not that we cry, strike, or tremble, because we are

sorry, angry, or fearful, as the case may be. Without the bodily

states following on the perception, the latter would be purely

cognitive in form, pale, colourless, destitute of emotional


Round this hypothesis a very voluminous literature has grown up.

The history of its victory over earlier criticism, and its

difficulties with the modern experimental work of Sherrington and

Cannon, is well told by James R. Angell in an article called "A

Reconsideration of James's Theory of Emotion in the Light of

Recent Criticisms."* In this article Angell defends James's

theory and to me--though I speak with diffidence on a question as

to which I have little competence--it appears that his defence is

on the whole successful.

* "Psychological Review," 1916.

Sherrington, by experiments on dogs, showed that many of the

usual marks of emotion were present in their behaviour even when,

by severing the spinal cord in the lower cervical region, the

viscera were cut off from all communication with the brain,

except that existing through certain cranial nerves. He mentions

the various signs which "contributed to indicate the existence of

an emotion as lively as the animal had ever shown us before the

spinal operation had been made."* He infers that the

physiological condition of the viscera cannot be the cause of the

emotion displayed under such circumstances, and concludes: "We

are forced back toward the likelihood that the visceral

expression of emotion is SECONDARY to the cerebral action

occurring with the psychical state.... We may with James accept

visceral and organic sensations and the memories and associations

of them as contributory to primitive emotion, but we must regard

them as re-enforcing rather than as initiating the psychosis."*

* Quoted by Angell, loc. cit.

Angell suggests that the display of emotion in such cases may be

due to past experience, generating habits which would require

only the stimulation of cerebral reflex arcs. Rage and some forms

of fear, however, may, he thinks, gain expression without the

brain. Rage and fear have been especially studied by Cannon,

whose work is of the greatest importance. His results are given

in his book, "Bodily Changes in Pain, Hunger, Fear and Rage" (D.

Appleton and Co., 1916).

The most interesting part of Cannon's book consists in the

investigation of the effects produced by secretion of adrenin.

Adrenin is a substance secreted into the blood by the adrenal

glands. These are among the ductless glands, the functions of

which, both in physiology and in connection with the emotions,

have only come to be known during recent years. Cannon found that

pain, fear and rage occurred in circumstances which affected the

supply of adrenin, and that an artificial injection of adrenin

could, for example, produce all the symptoms of fear. He studied

the effects of adrenin on various parts of the body; he found

that it causes the pupils to dilate, hairs to stand erect, blood

vessels to be constricted, and so on. These effects were still

produced if the parts in question were removed from the body and

kept alive artificially.*

* Cannon's work is not unconnected with that of Mosso, who

maintains, as the result of much experimental work, that "the

seat of the emotions lies in the sympathetic nervous system." An

account of the work of both these men will be found in Goddard's

"Psychology of the Normal and Sub-normal" (Kegan Paul, 1919),

chap. vii and Appendix.

Cannon's chief argument against James is, if I understand him

rightly, that similar affections of the viscera may accompany

dissimilar emotions, especially fear and rage. Various different

emotions make us cry, and therefore it cannot be true to say, as

James does, that we "feel sorry because we cry," since sometimes

we cry when we feel glad. This argument, however, is by no means

conclusive against James, because it cannot be shown that there

are no visceral differences for different emotions, and indeed it

is unlikely that this is the case.

As Angell says (loc. cit.): "Fear and joy may both cause cardiac

palpitation, but in one case we find high tonus of the skeletal

muscles, in the other case relaxation and the general sense of


Angell's conclusion, after discussing the experiments of

Sherrington and Cannon, is: "I would therefore submit that, so

far as concerns the critical suggestions by these two

psychologists, James's essential contentions are not materially

affected." If it were necessary for me to take sides on this

question, I should agree with this conclusion; but I think my

thesis as to the analysis of emotion can be maintained without

coming to. a probably premature conclusion upon the doubtful

parts of the physiological problem.

According to our definitions, if James is right, an emotion may

be regarded as involving a confused perception of the viscera

concerned in its causation, while if Cannon and Sherrington are

right, an emotion involves a confused perception of its external

stimulus. This follows from what was said in Lecture VII. We

there defined a perception as an appearance, however irregular,

of one or more objects external to the brain. And in order to be

an appearance of one or more objects, it is only necessary that

the occurrence in question should be connected with them by a

continuous chain, and should vary when they are varied

sufficiently. Thus the question whether a mental occurrence can

be called a perception turns upon the question whether anything

can be inferred from it as to its causes outside the brain: if

such inference is possible, the occurrence in question will come

within our definition of a perception. And in that case,

according to the definition in Lecture VIII, its non-mnemic

elements will be sensations. Accordingly, whether emotions are

caused by changes in the viscera or by sensible objects, they

contain elements which are sensations according to our


An emotion in its entirety is, of course, something much more

complex than a perception. An emotion is essentially a process,

and it will be only what one may call a cross-section of the

emotion that will be a perception, of a bodily condition

according to James, or (in certain cases) of an external object

according to his opponents. An emotion in its entirety contains

dynamic elements, such as motor impulses, desires, pleasures and

pains. Desires and pleasures and pains, according to the theory

adopted in Lecture III, are characteristics of processes, not

separate ingredients. An emotion--rage, for example--will be a

certain kind of process, consisting of perceptions and (in

general) bodily movements. The desires and pleasures and pains

involved are properties of this process, not separate items in

the stuff of which the emotion is composed. The dynamic elements

in an emotion, if we are right in our analysis, contain, from our

point of view, no ingredients beyond those contained in the

processes considered in Lecture III. The ingredients of an

emotion are only sensations and images and bodily movements

succeeding each other according to a certain pattern. With this

conclusion we may leave the emotions and pass to the

consideration of the will.

The first thing to be defined when we are dealing with Will is a

VOLUNTARY MOVEMENT. We have already defined vital movements, and

we have maintained that, from a behaviourist standpoint, it is

impossible to distinguish which among such movements are reflex

and which voluntary. Nevertheless, there certainly is a

distinction. When we decide in the morning that it is time to get

up, our consequent movement is voluntary. The beating of the

heart, on the other hand, is involuntary: we can neither cause it

nor prevent it by any decision of our own, except indirectly, as

e.g. by drugs. Breathing is intermediate between the two: we

normally breathe without the help of the will, but we can alter

or stop our breathing if we choose.

James ("Psychology," chap. xxvi) maintains that the only

distinctive characteristic of a voluntary act is that it involves

an idea of the movement to be performed, made up of memory-images

of the kinaesthetic sensations which we had when the same

movement occurred on some former occasion. He points out that, on

this view, no movement can be made voluntarily unless it has

previously occurred involuntarily.*

* "Psychology," Vol. ii, pp. 492-3.

I see no reason to doubt the correctness of this view. We shall

say, then, that movements which are accompanied by kinaesthetic

sensations tend to be caused by the images of those sensations,

and when so caused are called VOLUNTARY.

Volition, in the emphatic sense, involves something more than

voluntary movement. The sort of case I am thinking of is decision

after deliberation. Voluntary movements are a part of this, but

not the whole. There is, in addition to them, a judgment: "This

is what I shall do"; there is also a sensation of tension during

doubt, followed by a different sensation at the moment of

deciding. I see no reason whatever to suppose that there is any

specifically new ingredient; sensations and images, with their

relations and causal laws, yield all that seems to be wanted for

the analysis of the will, together with the fact that

kinaesthetic images tend to cause the movements with which they

are connected. Conflict of desires is of course essential in the

causation of the emphatic kind of will: there will be for a time

kinaesthetic images of incompatible movements, followed by the

exclusive image of the movement which is said to be willed. Thus

will seems to add no new irreducible ingredient to the analysis

of the mind.


At the end of our journey it is time to return to the question

from which we set out, namely: What is it that characterizes mind

as opposed to matter? Or, to state the same question in other

terms: How is psychology to be distinguished from physics? The

answer provisionally suggested at the outset of our inquiry was

that psychology and physics are distinguished by the nature of

their causal laws, not by their subject matter. At the same time

we held that there is a certain subject matter, namely images, to

which only psychological causal laws are applicable; this subject

matter, therefore, we assigned exclusively to psychology. But we

found no way of defining images except through their causation;

in their intrinsic character they appeared to have no universal

mark by which they could be distinguished from sensations.

In this last lecture I propose to pass in review various

suggested methods of distinguishing mind from matter. I shall

then briefly sketch the nature of that fundamental science which

I believe to be the true metaphysic, in which mind and matter

alike are seen to be constructed out of a neutral stuff, whose

causal laws have no such duality as that of psychology, but form

the basis upon which both physics and psychology are built.

In search for the definition of "mental phenomena," let us begin

with "consciousness," which is often thought to be the essence of

mind. In the first lecture I gave various arguments against the

view that consciousness is fundamental, but I did not attempt to

say what consciousness is. We must find a definition of it, if we

are to feel secure in deciding that it is not fundamental. It is

for the sake of the proof that it is not fundamental that we must

now endeavour to decide what it is.

"Consciousness," by those who regard it as fundamental, is taken

to be a character diffused throughout our mental life, distinct

from sensations and images, memories, beliefs and desires, but

present in all of them.* Dr. Henry Head, in an article which I

quoted in Lecture III, distinguishing sensations from purely

physiological occurrences, says: "Sensation, in the strict sense

of the term, demands the existence of consciousness." This

statement, at first sight, is one to which we feel inclined to

assent, but I believe we are mistaken if we do so. Sensation is

the sort of thing of which we MAY be conscious, but not a thing

of which we MUST be conscious. We have been led, in the course of

our inquiry, to admit unconscious beliefs and unconscious

desires. There is, so far as I can see, no class of mental or

other occurrences of which we are always conscious whenever they


* Cf. Lecture VI.

The first thing to notice is that consciousness must be of

something. In view of this, I should define "consciousness" in

terms of that relation of an image of a word to an object which

we defined, in Lecture XI, as "meaning." When a sensation is

followed by an image which is a "copy" of it, I think it may be

said that the existence of the image constitutes consciousness of

the sensation, provided it is accompanied by that sort of belief

which, when we reflect upon it, makes us feel that the image is a

"sign" of something other than itself. This is the sort of belief

which, in the case of memory, we expressed in the words "this

occurred"; or which, in the case of a judgment of perception,

makes us believe in qualities correlated with present sensations,

as e.g., tactile and visual qualities are correlated. The

addition of some element of belief seems required, since mere

imagination does not involve consciousness of anything, and there

can be no consciousness which is not of something. If images

alone constituted consciousness of their prototypes, such

imagination-images as in fact have prototypes would involve

consciousness of them; since this is not the case, an element of

belief must be added to the images in defining consciousness. The

belief must be of that sort that constitutes objective reference,

past or present. An image, together with a belief of this sort

concerning it, constitutes, according to our definition,

consciousness of the prototype of the image.

But when we pass from consciousness of sensations to

consciousness of objects of perception, certain further points

arise which demand an addition to our definition. A judgment of

perception, we may say, consists of a core of sensation, together

with associated images, with belief in the present existence of

an object to which sensation and images are referred in a way

which is difficult to analyse. Perhaps we might say that the

belief is not fundamentally in any PRESENT existence, but is of

the nature of an expectation: for example. when we see an object,

we expect certain sensations to result if we proceed to touch it.

Perception, then, will consist of a present sensation together

with expectations of future sensations. (This, of course, is a

reflective analysis, not an account of the way perception appears

to unchecked introspection.) But all such expectations are liable

to be erroneous, since they are based upon correlations which are

usual but not invariable. Any such correlation may mislead us in

a particular case, for example, if we try to touch a reflection

in a looking-glass under the impression that it is "real." Since

memory is fallible, a similar difficulty arises as regards

consciousness of past objects. It would seem odd to say that we

can be "conscious" of a thing which does not or did not exist.

The only way to avoid this awkwardness is to add to our

definition the proviso that the beliefs involved in consciousness

must be TRUE.

In the second place, the question arises as to whether we can be

conscious of images. If we apply our definition to this case, it

seems to demand images of images. In order, for example, to be

conscious of an image of a cat, we shall require, according to

the letter of the definition, an image which is a copy of our

image of the cat, and has this image for its prototype. Now, it

hardly seems probable, as a matter of observation, that there are

images of images, as opposed to images of sensations. We may meet

this difficulty in two ways, either by boldly denying

consciousness of images, or by finding a sense in which, by means

of a different accompanying belief, an image, instead of meaning

its prototype, can mean another image of the same prototype.

The first alternative, which denies consciousness of images, has

already been discussed when we were dealing with Introspection in

Lecture VI. We then decided that there must be, in some sense,

consciousness of images. We are therefore left with the second

suggested way of dealing with knowledge of images. According to

this second hypothesis, there may be two images of the same

prototype, such that one of them means the other, instead of

meaning the prototype. It will be remembered that we defined

meaning by association a word or image means an object, we said,

when it has the same associations as the object. But this

definition must not be interpreted too absolutely: a word or

image will not have ALL the same associations as the object which

it means. The word "cat" may be associated with the word "mat,"

but it would not happen except by accident that a cat would be

associated with a mat. And in like manner an image may have

certain associations which its prototype will not have, e.g. an

association with the word "image." When these associations are

active, an image means an image, instead of meaning its

prototype. If I have had images of a given prototype many times,

I can mean one of these, as opposed to the rest, by recollecting

the time and place or any other distinctive association of that

one occasion. This happens, for example, when a place recalls to

us some thought we previously had in that place, so that we

remember a thought as opposed to the occurrence to which it

referred. Thus we may say that we think of an image A when we

have a similar image B associated with recollections of

circumstances connected with A, but not with its prototype or

with other images of the same prototype. In this way we become

aware of images without the need of any new store of mental

contents, merely by the help of new associations. This theory, so

far as I can see, solves the problems of introspective knowledge,

without requiring heroic measures such as those proposed by

Knight Dunlap, whose views we discussed in Lecture VI.

According to what we have been saying, sensation itself is not an

instance of consciousness, though the immediate memory by which

it is apt to be succeeded is so. A sensation which is remembered

becomes an object of consciousness as soon as it begins to be

remembered, which will normally be almost immediately after its

occurrence (if at all); but while it exists it is not an object

of consciousness. If, however, it is part of a perception, say of

some familiar person, we may say that the person perceived is an

object of consciousness. For in this case the sensation is a SIGN

of the perceived object in much the same way in which a

memory-image is a sign of a remembered object. The essential

practical function of "consciousness" and "thought" is that they

enable us to act with reference to what is distant in time or

space, even though it is not at present stimulating our senses.

This reference to absent objects is possible through association

and habit. Actual sensations, in themselves, are not cases of

consciousness, because they do not bring in this reference to

what is absent. But their connection with consciousness is very

close, both through immediate memory, and through the

correlations which turn sensations into perceptions.

Enough has, I hope, been said to show that consciousness is far

too complex and accidental to be taken as the fundamental

characteristic of mind. We have seen that belief and images both

enter into it. Belief itself, as we saw in an earlier lecture, is

complex. Therefore, if any definition of mind is suggested by our

analysis of consciousness, images are what would naturally

suggest themselves. But since we found that images can only be

defined causally, we cannot deal with this suggestion, except in

connection with the difference between physical and psychological

causal laws.

I come next to those characteristics of mental phenomena which

arise out of mnemic causation. The possibility of action with

reference to what is not sensibly present is one of the things

that might be held to characterize mind. Let us take first a very

elementary example. Suppose you are in a familiar room at night,

and suddenly the light goes out. You will be able to find your

way to the door without much difficulty by means of the picture

of the room which you have in your mind. In this case visual

images serve, somewhat imperfectly it is true, the purpose which

visual sensations would otherwise serve. The stimulus to the

production of visual images is the desire to get out of the room,

which, according to what we found in Lecture III, consists

essentially of present sensations and motor impulses caused by

them. Again, words heard or read enable you to act with reference

to the matters about which they give information; here, again, a

present sensible stimulus, in virtue of habits formed in the

past, enables you to act in a manner appropriate to an object

which is not sensibly present. The whole essence of the practical

efficiency of "thought" consists in sensitiveness to signs: the

sensible presence of A, which is a sign of the present or future

existence of B, enables us to act in a manner appropriate to B.

Of this, words are the supreme example, since their effects as

signs are prodigious, while their intrinsic interest as sensible

occurrences on their own account is usually very slight. The

operation of signs may or may not be accompanied by

consciousness. If a sensible stimulus A calls up an image of B,

and we then act with reference to B, we have what may be called

consciousness of B. But habit may enable us to act in a manner

appropriate to B as soon as A appears, without ever having an

image of B. In that case, although A operates as a sign, it

operates without the help of consciousness. Broadly speaking, a

very familiar sign tends to operate directly in this manner, and

the intervention of consciousness marks an imperfectly

established habit.

The power of acquiring experience, which characterizes men and

animals, is an example of the general law that, in mnemic

causation, the causal unit is not one event at one time, but two

or more events at two or more times.& A burnt child fears the

fire, that is to say, the neighbourhood of fire has a different

effect upon a child which has had the sensations of burning than

upon one which has not. More correctly, the observed effect, when

a child which has been burnt is put near a fire, has for its

cause, not merely the neighbourhood of the fire, but this

together with the previous burning. The general formula, when an

animal has acquired experience through some event A, is that,

when B occurs at some future time, the animal to which A has

happened acts differently from an animal which A has not

happened. Thus A and B together, not either separately, must be

regarded as the cause of the animal's behaviour, unless we take

account of the effect which A has had in altering the animal's

nervous tissue, which is a matter not patent to external

observation except under very special circumstances. With this

possibility, we are brought back to causal laws,and to the

suggestion that many things which seem essentially mental are

really neural. Perhaps it is the nerves that acquire experience

rather than the mind. If so, the possibility of acquiring

experience cannot be used to define mind.*

* Cf. Lecture IV.

Very similar considerations apply to memory, if taken as the

essence of mind. A recollection is aroused by something which is

happening now, but is different from the effect which the present

occurrence would have produced if the recollected event had not

occurred. This may be accounted for by the physical effect of the

past event on the brain, making it a different instrument from

that which would have resulted from a different experience. The

causal peculiarities of memory may, therefore, have a

physiological explanation. With every special class of mental

phenomena this possibility meets us afresh. If psychology is to

be a separate science at all, we must seek a wider ground for its

separateness than any that we have been considering hitherto.

We have found that "consciousness" is too narrow to characterize

mental phenomena, and that mnemic causation is too wide. I come

now to a characteristic which, though difficult to define, comes

much nearer to what we require, namely subjectivity.

Subjectivity, as a characteristic of mental phenomena, was

considered in Lecture VII, in connection with the definition of

perception. We there decided that those particulars which

constitute the physical world can be collected into sets in two

ways, one of which makes a bundle of all those particulars that

are appearances of a given thing from different places, while the

other makes a bundle of all those particulars which are

appearances of different things from a given place. A bundle of

this latter sort, at a given time, is called a "perspective";

taken throughout a period of time, it is called a "biography."

Subjectivity is the characteristic of perspectives and

biographies, the characteristic of giving the view of the world

from a certain place. We saw in Lecture VII that this

characteristic involves none of the other characteristics that

are commonly associated with mental phenomena, such as

consciousness, experience and memory. We found in fact that it is

exhibited by a photographic plate, and, strictly speaking, by any

particular taken in conjunction with those which have the same

"passive" place in the sense defined in Lecture VII. The

particulars forming one perspective are connected together

primarily by simultaneity; those forming one biography, primarily

by the existence of direct time-relations between them. To these

are to be added relations derivable from the laws of perspective.

In all this we are clearly not in the region of psychology, as

commonly understood; yet we are also hardly in the region of

physics. And the definition of perspectives and biographies,

though it does not yet yield anything that would be commonly

called "mental," is presupposed in mental phenomena, for example

in mnemic causation: the causal unit in mnemic causation, which

gives rise to Semon's engram, is the whole of one perspective--

not of any perspective, but of a perspective in a place where

there is nervous tissue, or at any rate living tissue of some

sort. Perception also, as we saw, can only be defined in terms of

perspectives. Thus the conception of subjectivity, i.e. of the

"passive" place of a particular, though not alone sufficient to

define mind, is clearly an essential element in the definition.

I have maintained throughout these lectures that the data of

psychology do not differ in, their intrinsic character from the

data of physics. I have maintained that sensations are data for

psychology and physics equally, while images, which may be in

some sense exclusively psychological data, can only be

distinguished from sensations by their correlations, not by what

they are in themselves. It is now necessary, however, to examine

the notion of a "datum," and to obtain, if possible, a definition

of this notion.

The notion of "data" is familiar throughout science, and is

usually treated by men of science as though it were perfectly

clear. Psychologists, on the other hand, find great difficulty in

the conception. "Data" are naturally defined in terms of theory

of knowledge: they are those propositions of which the truth is

known without demonstration, so that they may be used as

premisses in proving other propositions. Further, when a

proposition which is a datum asserts the existence of something,

we say that the something is a datum, as well as the proposition

asserting its existence. Thus those objects of whose existence we

become certain through perception are said to be data.

There is some difficulty in connecting this epistemological

definition of "data" with our psychological analysis of

knowledge; but until such a connection has been effected, we have

no right to use the conception "data."

It is clear, in the first place, that there can be no datum apart

from a belief. A sensation which merely comes and goes is not a

datum; it only becomes a datum when it is remembered. Similarly,

in perception, we do not have a datum unless we have a JUDGMENT

of perception. In the sense in which objects (as opposed to

propositions) are data, it would seem natural to say that those

objects of which we are conscious are data. But consciousness, as

we have seen, is a complex notion, involving beliefs, as well as

mnemic phenomena such as are required for perception and memory.

It follows that no datum is theoretically indubitable, since no

belief is infallible; it follows also that every datum has a

greater or less degree of vagueness, since there is always some

vagueness in memory and the meaning of images.

Data are not those things of which our consciousness is earliest

in time. At every period of life, after we have become capable of

thought, some of our beliefs are obtained by inference, while

others are not. A belief may pass from either of these classes

into the other, and may therefore become, or cease to be, a

belief giving a datum. When, in what follows, I speak of data, I

do not mean the things of which we feel sure before scientific

study begins, but the things which, when a science is well

advanced, appear as affording grounds for other parts of the

science, without themselves being believed on any ground except

observation. I assume, that is to say, a trained observer, with

an analytic attention, knowing the sort of thing to look for, and

the sort of thing that will be important. What he observes is, at

the stage of science which he has reached, a datum for his

science. It is just as sophisticated and elaborate as the

theories which he bases upon it, since only trained habits and

much practice enable a man to make the kind of observation that

will be scientifically illuminating. Nevertheless, when once it

has been observed, belief in it is not based on inference and

reasoning, but merely upon its having been seen. In this way its

logical status differs from that of the theories which are proved

by its means.

In any science other than psychology the datum is primarily a

perception, in which only the sensational core is ultimately and

theoretically a datum, though some such accretions as turn the

sensation into a perception are practically unavoidable. But if

we postulate an ideal observer, he will be able to isolate the

sensation, and treat this alone as datum. There is, therefore, an

important sense in which we may say that, if we analyse as much

as we ought, our data, outside psychology, consist of sensations,

which include within themselves certain spatial and temporal


Applying this remark to physiology, we see that the nerves and

brain as physical objects are not truly data; they are to be

replaced, in the ideal structure of science, by the sensations

through which the physiologist is said to perceive them. The

passage from these sensations to nerves and brain as physical

objects belongs really to the initial stage in the theory of

physics, and ought to be placed in the reasoned part, not in the

part supposed to be observed. To say we see the nerves is like

saying we hear the nightingale; both are convenient but

inaccurate expressions. We hear a sound which we believe to be

causally connected with the nightingale, and we see a sight which

we believe to be causally connected with a nerve. But in each

case it is only the sensation that ought, in strictness, to be

called a datum. Now, sensations are certainly among the data of

psychology. Therefore all the data of the physical sciences are

also psychological data. It remains to inquire whether all the

data of psychology are also data of physical science, and

especially of physiology.

If we have been right in our analysis of mind, the ultimate data

of psychology are only sensations and images and their relations.

Beliefs, desires, volitions, and so on, appeared to us to be

complex phenomena consisting of sensations and images variously

interrelated. Thus (apart from certain relations) the occurrences

which seem most distinctively mental, and furthest removed from

physics, are, like physical objects, constructed or inferred, not

part of the original stock of data in the perfected science. From

both ends, therefore, the difference between physical and

psychological data is diminished. Is there ultimately no

difference, or do images remain as irreducibly and exclusively

psychological? In view of the causal definition of the difference

between images and sensations, this brings us to a new question,

namely: Are the causal laws of psychology different from those of

any other science, or are they really physiological?

Certain ambiguities must be removed before this question can be

adequately discussed.

First, there is the distinction between rough approximate laws

and such as appear to be precise and general. I shall return to

the former presently; it is the latter that I wish to discuss


Matter, as defined at the end of Lecture V, is a logical fiction,

invented because it gives a convenient way of stating causal

laws. Except in cases of perfect regularity in appearances (of

which we can have no experience), the actual appearances of a

piece of matter are not members of that ideal system of regular

appearances which is defined as being the matter in question. But

the matter is. after all, inferred from its appearances, which

are used to VERIFY physical laws. Thus, in so far as physics is

an empirical and verifiable science, it must assume or prove that

the inference from appearances to matter is, in general,

legitimate, and it must be able to tell us, more or less, what

appearances to expect. It is through this question of

verifiability and empirical applicability to experience that we

are led to a theory of matter such as I advocate. From the

consideration of this question it results that physics, in so far

as it is an empirical science, not a logical phantasy, is

concerned with particulars of just the same sort as those which

psychology considers under the name of sensations. The causal

laws of physics, so interpreted, differ from those of psychology

only by the fact that they connect a particular with other

appearances in the same piece of matter, rather than with other

appearances in the same perspective. That is to say, they group

together particulars having the same "active" place, while

psychology groups together those having the same "passive" place.

Some particulars, such as images, have no "active" place, and

therefore belong exclusively to psychology.

We can now understand the distinction between physics and

psychology. The nerves and brain are matter: our visual

sensations when we look at them may be, and I think are, members

of the system constituting irregular appearances of this matter,

but are not the whole of the system. Psychology is concerned,

inter alia, with our sensations when we see a piece of matter, as

opposed to the matter which we see. Assuming, as we must, that

our sensations have physical causes, their causal laws are

nevertheless radically different from the laws of physics, since

the consideration of a single sensation requires the breaking up

of the group of which it is a member. When a sensation is used to

verify physics, it is used merely as a sign of a certain material

phenomenon, i.e. of a group of particulars of which it is a

member. But when it is studied by psychology, it is taken away

from that group and put into quite a different context, where it

causes images or voluntary movements. It is primarily this

different grouping that is characteristic of psychology as

opposed to all the physical sciences, including physiology; a

secondary difference is that images, which belong to psychology,

are not easily to be included among the aspects which constitute

a physical thing or piece of matter.

There remains, however, an important question, namely: Are mental

events causally dependent upon physical events in a sense in

which the converse dependence does not hold? Before we can

discuss the answer to this question, we must first be clear as to

what our question means.

When, given A, it is possible to infer B, but given B, it is not

possible to infer A, we say that B is dependent upon A in a sense

in which A is not dependent upon B. Stated in logical terms, this

amounts to saying that, when we know a many-one relation of A to

B, B is dependent upon A in respect of this relation. If the

relation is a causal law, we say that B is causally dependent

upon A. The illustration that chiefly concerns us is the system

of appearances of a physical object. We can, broadly speaking,

infer distant appearances from near ones, but not vice versa. All

men look alike when they are a mile away, hence when we see a man

a mile off we cannot tell what he will look like when he is only

a yard away. But when we see him a yard away, we can tell what he

will look like a mile away. Thus the nearer view gives us more

valuable information, and the distant view is causally dependent

upon it in a sense in which it is not causally dependent upon the

distant view.

It is this greater causal potency of the near appearance that

leads physics to state its causal laws in terms of that system of

regular appearances to which the nearest appearances increasingly

approximate, and that makes it value information derived from the

microscope or telescope. It is clear that our sensations,

considered as irregular appearances of physical objects, share

the causal dependence belonging to comparatively distant

appearances; therefore in our sensational life we are in causal

dependence upon physical laws.

This, however, is not the most important or interesting part of

our question. It is the causation of images that is the vital

problem. We have seen that they are subject to mnenic causation,

and that mnenic causation may be reducible to ordinary physical

causation in nervous tissue. This is the question upon which our

attitude must turn towards what may be called materialism. One

sense of materialism is the view that all mental phenomena are

causally dependent upon physical phenomena in the above-defined

sense of causal dependence. Whether this is the case or not, I do

not profess to know. The question seems to me the same as the

question whether mnemic causation is ultimate, which we

considered without deciding in Lecture IV. But I think the bulk

of the evidence points to the materialistic answer as the more


In considering the causal laws of psychology, the distinction

between rough generalizations and exact laws is important. There

are many rough generalizations in psychology, not only of the

sort by which we govern our ordinary behaviour to each other, but

also of a more nearly scientific kind. Habit and association

belong among such laws. I will give an illustration of the kind

of law that can be obtained. Suppose a person has frequently

experienced A and B in close temporal contiguity, an association

will be established, so that A, or an image of A, tends to cause

an image of B. The question arises: will the association work in

either direction, or only from the one which has occurred earlier

to the one which has occurred later? In an article by Mr.

Wohlgemuth, called "The Direction of Associations" ("British

Journal of Psychology," vol. v, part iv, March, 1913), it is

claimed to be proved by experiment that, in so far as motor

memory (i.e. memory of movements) is concerned, association works

only from earlier to later, while in visual and auditory memory

this is not the case, but the later of two neighbouring

experiences may recall the earlier as well as the earlier the

later. It is suggested that motor memory is physiological, while

visual and auditory memory are more truly psychological. But that

is not the point which concerns us in the illustration. The point

which concerns us is that a law of association, established by

purely psychological observation, is a purely psychological law,

and may serve as a sample of what is possible in the way of

discovering such laws. It is, however, still no more than a rough

generalization, a statistical average. It cannot tell us what

will result from a given cause on a given occasion. It is a law

of tendency, not a precise and invariable law such as those of

physics aim at being.

If we wish to pass from the law of habit, stated as a tendency or

average, to something more precise and invariable, we seem driven

to the nervous system. We can more or less guess how an

occurrence produces a change in the brain, and how its repetition

gradually produces something analogous to the channel of a river,

along which currents flow more easily than in neighbouring paths.

We can perceive that in this way, if we had more knowledge, the

tendency to habit through repetition might be replaced by a

precise account of the effect of each occurrence in bringing

about a modification of the sort from which habit would

ultimately result. It is such considerations that make students

of psychophysiology materialistic in their methods, whatever they

may be in their metaphysics. There are, of course, exceptions,

such as Professor J. S. Haldane,* who maintains that it is

theoretically impossible to obtain physiological explanations of

psychical phenomena, or physical explanations of physiological

phenomena. But I think the bulk of expert opinion, in practice,

is on the other side.

*See his book, "The New Physiology and Other Addresses" (Charles

Griffin & Co., 1919).

The question whether it is possible to obtain precise causal laws

in which the causes are psychological, not material, is one of

detailed investigation. I have done what I could to make clear

the nature of the question, but I do not believe that it is

possible as yet to answer it with any confidence. It seems to be

by no means an insoluble question, and we may hope that science

will be able to produce sufficient grounds for regarding one

answer as much more probable than the other. But for the moment I

do not see how we can come to a decision.

I think, however, on grounds of the theory of matter explained in

Lectures V and VII, that an ultimate scientific account of what

goes on in the world, if it were ascertainable, would resemble

psychology rather than physics in what we found to be the

decisive difference between them. I think, that is to say, that

such an account would not be content to speak, even formally, as

though matter, which is a logical fiction, were the ultimate

reality. I think that, if our scientific knowledge were adequate

to the task, which it neither is nor is likely to become, it

would exhibit the laws of correlation of the particulars

constituting a momentary condition of a material unit, and would

state the causal laws* of the world in terms of these

particulars, not in terms of matter. Causal laws so stated would,

I believe, be applicable to psychology and physics equally; the

science in which they were stated would succeed in achieving what

metaphysics has vainly attempted, namely a unified account of

what really happens, wholly true even if not the whole of truth,

and free from all convenient fictions or unwarrantable

assumptions of metaphysical entities. A causal law applicable to

particulars would count as a law of physics if it could be stated

in terms of those fictitious systems of regular appearances which

are matter; if this were not the case, it would count as a law of

psychology if one of the particulars were a sensation or an

image, i.e. were subject to mnemic causation. I believe that the

realization of the complexity of a material unit, and its

analysis into constituents analogous to sensations, is of the

utmost importance to philosophy, and vital for any understanding

of the relations between mind and matter, between our perceptions

and the world which they perceive. It is in this direction, I am

convinced, that we must look for the solution of many ancient


* In a perfected science, causal laws will take the form of

differential equations--or of finite-difference equations, if the

theory of quanta should prove correct.

It is probable that the whole science of mental occurrences,

especially where its initial definitions are concerned, could be

simplified by the development of the fundamental unifying science

in which the causal laws of particulars are sought, rather than

the causal laws of those systems of particulars that constitute

the material units of physics. This fundamental science would

cause physics to become derivative, in the sort of way in which

theories of the constitution of the atom make chemistry

derivative from physics; it would also cause psychology to appear

less singular and isolated among sciences. If we are right in

this, it is a wrong philosophy of matter which has caused many of

the difficulties in the philosophy of mind--difficulties which a

right philosophy of matter would cause to disappear.

The conclusions at which we have arrived may be summed up as


I. Physics and psychology are not distinguished by their

material. Mind and matter alike are logical constructions; the

particulars out of which they are constructed, or from which they

are inferred, have various relations, some of which are studied

by physics, others by psychology. Broadly speaking, physics group

particulars by their active places, psychology by their passive


II. The two most essential characteristics of the causal laws

which would naturally be called psychological are SUBJECTIVITY

and MNEMIC CAUSATION; these are not unconnected, since the causal

unit in mnemic causation is the group of particulars having a

given passive place at a given time, and it is by this manner of

grouping that subjectivity is defined.

III. Habit, memory and thought are all developments of mnemic

causation. It is probable, though not certain, that mnemic

causation is derivative from ordinary physical causation in

nervous (and other) tissue.

IV. Consciousness is a complex and far from universal

characteristic of mental phenomena.

V. Mind is a matter of degree, chiefly exemplified in number and

complexity of habits.

VI. All our data, both in physics and psychology, are subject to

psychological causal laws; but physical causal laws, at least in

traditional physics, can only be stated in terms of matter, which

is both inferred and constructed, never a datum. In this respect

psychology is nearer to what actually exists.

End of the Project Gutenberg Etext of The Analysis of Mind by Bertrand


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