When you see a table, you not only see a colored surface, but realize that it is hard.

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.

"Thought" in the narrower sense is that form of consciousness which consists in "Ideas" as opposed to impressions or mere memories.

BELIEF, by which I mean that way of being conscious which may be either true or false. It is the form which gives "Knowledge" in the strict sense, and also Error.

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.

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.

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.

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.

when it comes to ourselves, we feel convinced that we can actually perceive our own thinking.

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.

it might well be maintained that desiring is what is really most characteristic of Mind.

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.

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).

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.

The essential point of the definition, from our point of view, is that an instinctive movement is in dependent of prior experience.

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.

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.

The process of learning, which consists in the acquisition of Habits,

Learning is only possible when instinct supplies the driving-force.

But for these random movements, they would never acquire the experience which afterwards enables them to produce the right movement.

It is clear that the original making of random sounds, without which speech would never be learnt, is instinctive.

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.

The essence of "experience" is the modification of behaviour produced by what is experienced. I (Russell) think it is this characteristic, more than any other, that distinguishes sciences dealing with living organisms from physics.

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.

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.

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.

Habit is a characteristic of the body at least as much as of the mind.

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.

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.

Cause and effect, therefore, will have to be temporally contiguous processes.

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.

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.

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.

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.

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.

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.

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.

Images, though they USUALLY have certain characteristics, especially lack of vividness, that distinguish them from Sensations, are not INVARIABLY so distinguished,

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.

I think that some of the things we observe cannot, even theoretically, be observed by any one else.

observation shows us nothing that is not composed of sensations and images, and that images differ from sensations in their causal laws, not intrinsically.

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.

The whole distinction of privacy and publicity, however, so long as we confine ourselves to sensations, is one of degree, not of kind.

Two people looking at the same table do not get the same sensation, because of perspective and the way the light falls.

Privacy, therefore does not by itself make a datum unamenable to scientific treatment. On this point, the argument against introspection must be rejected.

But it would seem that "knowing" is really various Relations, all of them complex.

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.

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.

But from the standpoint of theoretical logic it must be regarded as a prejudice, not as a well-grounded theory.

All actual perception is confused to a greater or less extent.

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.

With this definition, we can define a sensation as the non-mnemic elements in a perception.

we should similarly discover how much of what we think we see is really inference.

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.

It might seem natural to regard a sensation as itself a cognition, and until lately I did so regard it.

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.

The functions that they appear to perform can always be performed by classes or Series or other logical constructions, consisting of less dubious entities.

the possibility of distinguishing the sensation from the sense-datum vanishes;

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.

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.

Sensations are what is common to the mental and physical worlds; they may be defined as the intersection of Mind and Matter.

The essence of sensation, according to the view I am advocating, is its independence of past Experience.

I think the only ingredients required in addition to sensations are images.

By the fact that their causes and effects are different from those of sensations.

But so far we have seen no reason to think that the difference between sensations and images is only one of degree.

I think the more reliable distinction is by their causes.

Sensations come through sense-organs, while images do not.

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.

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.

The point is important, because what is called "thought" consists mainly (though I think not wholly) of inner speech.

as education advances, images tend to be more and more replaced by Words.

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,

there can be no doubt that memory forms an indispensable part of our Knowledge of the past.

define "memory" as that way of knowing about the past which has no analogue in our knowledge of the future;

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.

Whether knowledge itself is reducible to Habit is a question to which I shall return in a later lecture;

Arguments in favour of (for example) memory in plants are only arguments in favour of Habit-memory, not of knowledge-memory.

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 past.

It differs from the sense of familiarity by being cognitive; it is a belief or judgment, which the sense of familiarity is not.

I merely wish to emphasize the fact that recognition, in our second sense, consists in a Belief,

It is sometimes suggested, by those who favor 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.

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.

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.

The specious present includes elements at all stages on the journey from sensation to image.

At the beginning of a stimulus we have a sensation; then a gradual transition; and at the end an image.

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.

All thinking is vague to some extent, and complete accuracy is a theoretical ideal not practically attainable.

It follows from what has been said that a vague thought has more likelihood of being true than a precise one.

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.*

in the crude use of the word, which is what concerns us, memory-images would not be said to occur;

"real" things would be those that can cause sensations, those that have correlations of the sort that constitute physical objects.

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.

Memory demands (a) an Image, (b) a Belief in past existence. The belief may be expressed in the words "this existed."

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.

Thus an instance of walking differs from an instance of man solely by the fact that it has a shorter life.

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.

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.

Thus the problem of the Meaning of words is brought into connection with the problem of the meaning of images.

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.

The more familiar we are with words, the more our "thinking" goes on in words instead of images.

George Berkeley and David 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.

Generality and particularity are a matter of degree.

this sets a bound to the particularity of meaning.

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.

Almost all higher intellectual activity is a matter of words, to the nearly total exclusion of everything else.

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.

what distinguishes a general idea from a vague idea is merely the presence of a certain accompanying Belief.

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.

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 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.

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.

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(Bertrand Russell) to fail in the last analysis because it is based upon an inadequate philosophy of physics.

Belief, which is our subject to-day, is the central problem in the analysis of Mind.

Beliefs give Knowledge and Error; they are the vehicles of Truth and falsehood.

just as Meaning consists in relation to the object meant, so truth and falsehood consist in relation to something that lies outside the belief.

It assumes, if it is thought out, something like the mystic unity of knower and known.

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.

The content of a belief involves not merely a plurality of constituents, but definite Relations between them; 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.

In a PURE memory-belief only images occur. But a mixture of Words and Images is very common in memory.

The more complicated forms of belief tend to consist only 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.

The reason is that objective reference is of the essence of belief, and objective reference is derived from meaning.

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.

Not any series of words is a proposition, but only such series of words as have "Meaning," or, in our phraseology, "objective reference."

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.

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.

Most of our beliefs, like most of our wishes, are "Unconscious," in the sense that we have never told ourselves that we have them.


Doubt, suspense of judgment and disbelief all seem later and more complex than a wholly unreflecting assent.

It will not, for example, explain memory.

We wish to believe that our beliefs, sometimes at least, yield KNOWLEDGE, and a belief does not yield knowledge unless it is true.

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.

we shall find no reason to accept them.

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.

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.

The fundamental objection to this view is logical, and consists in a criticism of its doctrine as to relations.

I will content myself with saying that the powers of logic seem to me very much less than this theory supposes.

Another objection is that no endeavour is made to show that we cannot form a consistent whole composed partly or wholly of false propositions,

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.

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.

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 propositions asserting negative facts are themselves positive facts; they are merely different positive facts from those asserting positive facts.

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.

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.

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.

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.* Very similar considerations apply to Memory, if taken as the essence of mind.

Matter, as defined at the end of Lecture V, is a logical fiction, invented because it gives a convenient way of stating causal laws.

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.

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.

Broadly speaking, physics group particulars by their active places, psychology by their passive places.