# An Outline of Philosophy/Chapter 16

PART III
MAN FROM WITHIN
It will be remembered that, throughout Part I., we agreed to consider only those facts about a man which can be dis covered by external observation, and we postponed the question whether this excluded any genuine knowledge or not. The usual view is that we know many things which could not be known without self-observation, but the behaviourist holds that this view is mistaken. I might be inclined to agree wholly with the behaviourist but for the considerations which were forced upon us in Part II., when we were examining our knowledge of the physical world. We were then led to the conclusion that, assuming physics to be correct, the data for our knowledge of physics are infected with subjectivity, and it is impossible for two men to observe the same phenomenon except in a rough and approximate sense. This undermines the supposed objectivity of the behaviourist method, at least in principle; as a matter of degree, it may survive to some extent. Broadly speaking, if physics is true and if we accept a behaviourist definition of knowledge such as that of Chapter VIII., we ought, as a rule, to know more about things that happen near the brain than about things that happen far from it, and most of all about things that happen in the brain. This seemed untrue because people thought that what happens in the brain is what the physiologist sees when he examines it; but this, according to the theory of Chapter XII., happens in the brain of the physiologist. Thus the a priori objection to the view that we know best what happens in our brains ​is removed, and we are led back to self-observation as the most reliable way of obtaining knowledge. This is the thesis which is to be expanded and sustained in the present chapter.
As everyone knows, the certainty of self-observation was the basis of Descartes' system, with which modern philosophy began. Descartes, being anxious to build his metaphysic only upon what was absolutely certain, set to work, as a preliminary, to doubt anything that he could make himself doubt. He succeeded in doubting the whole external world, since there might be a malicious demon who took pleasure in presenting deceitful appearances to him. (For that matter, dreams would have supplied a sufficient argument.) But he could not manage to doubt his own existence. For, said he, I am really doubting; whatever else may be doubtful, the fact that I doubt is indubitable. And I could not doubt if I did not exist. He summed up the argument in his famous formula: I think, therefore I am. And having arrived at this certainty, he proceeded to build up the world again by successive inferences. Oddly enough, it was very like the world in which he had believed before his excursion into scepticism.
It is instructive to contrast this argument with Dr. Watson's. Dr. Watson, like Descartes, is sceptical of many things which others accept without question; and, like Descartes, he believes that there are some things so certain that they can be safely used as the basis of a startling philosophy. But the things which Dr. Watson regards as certain are just those which Descartes regarded as doubtful, and the thing which Dr. Watson most vehemently rejects is just what Descartes regarded as absolutely unquestionable. Dr. Watson maintains that there is no such thing as thinking. No doubt he believes in his own existence, but not because he thinks he can think. The things that strike him as absolutely indubitable are rats in mazes, time-measurements, physiological facts about glands and muscles, and so on. What are we to think when two able men hold such opposite views? The natural inference would be that everything is doubtful. This may be true, but there are ​degrees of doubtfulness, and we should like to know which of these two philosophers, if either, is right as to the region of minimum doubtfulness.
Let us begin by examining Descartes' view. "I think, therefore I am" is what he says, but this won't do as it stands. What, from his own point of view, he should profess to know is not "I think", but"there is thinking". He finds doubt going on, and says: There is doubt. Doubt is a form of thought, therefore there is thought. To trans late this into "I think" is to assume a great deal that a previous exercise in scepticism ought to have taught Descartes to call in question. He would say that thoughts imply a thinker. But why should they? Why should not a thinker be simply a certain series of thoughts, connected with each other by causal laws? Descartes believed in "substance", both in the mental and in the material world. He thought that there could not be motion unless something moved, nor thinking unless someone thought. No doubt most people would still hold this view; but in fact it springs from a notion—usually unconscious—that the categories of grammar are also the categories of reality. We have already seen that "matter" is merely a name for certain strings of sets of events. It follows that what we call motion of matter really means that the centre of such a set of events at one time does not have the same spatial relations to other events as the connected centre at another time has to the connected other events. It does not mean that there is a definite entity, a piece of matter, which is now in one place and now in another. Similarly, when we say, "I think first this and then that", we ought not to mean that there is a single entity "I" which "has" two successive thoughts. We ought to mean only that there are two successive thoughts which have causal relations of the kind that makes us call them parts of one biography, in the same sort of way in which successive notes may be parts of one tune; and that these thoughts are connected with the body which is speaking in the way (to be further investigated) in which thoughts and bodies are connected. All this is rather complicated, ​and cannot be admitted as part of any ultimate certainty. What Descartes really felt sure about was a certain occurrence, which he described in the words "I think". But the words were not quite an accurate representation of the occurrence; indeed, words never can escape from certain grammatical and social requirements which make them say at once more and less than we really mean. I think we ought to admit that Descartes was justified in feeling sure that there was a certain occurrence, concerning which doubt was impossible; but he was not justified in bringing in the word "I" in describing this occurrence, and it remains to be considered whether he was justified in using the word "think".
In using a general word such as "think", we are obviously going beyond the datum, from a logical point of view. We are subsuming a particular occurrence under a heading, and the heading is derived from past experience. Now all words are applicable to many occurrences; therefore all words go beyond any possible datum. In this sense, it is impossible ever to convey in words the particularity of a concrete experience; all words are more or less abstract. Such, at least, is a plausible line of argument, but I am by no means sure that it is valid. For example, the sight of a particular dog may make the general word "dog" come into your mind; you then know that it is a dog, but you may not notice what sort of dog it is. In this sense, the knowledge with which we start is abstract and general; that is to say, it consists of a learned reaction to a stimulus of a certain sort. The reactions, at any rate in so far as they are verbal, are more uniform than the stimuli. A witness might be asked "Did you see a dog?" "Yes." "What sort of dog?" "Oh just an ordinary dog; I don't remember more about it." That is to say, the witness's reaction consisted of the generalised word "dog" and no more. One is almost reminded of quantum phenomena in the atom. When light falls on a hydrogen atom, it may make the electron jump from the first orbit to the second, or to the third, or etc. Each of these is a generalised reaction to a stimulus which ​has no corresponding generality. So dogs and cats have each their individual peculiarities, but the ordinary inobservant person responds with the generalised reaction "dog" or "cat", and the particularity of the stimulus leads to no corresponding particularity in the knowledge-reaction.
To return to Descartes and his thinking: it is possible, according to what we have just said, that Descartes knew he was thinking with more certainty than he knew what he was thinking about. This possibility requires that we should ask what he meant by "thinking". And since, for him, thinking was the primitive certainty, we must not introduce any external stimulus, since he considered it possible to doubt whether anything external existed.
Descartes used the word "thinking" somewhat more widely than we should generally do nowadays. He included all perception, emotion, and volition, not only what are called "intellectual" processes. We may perhaps with advantage concentrate upon perception. Descartes would say that, when he "sees the moon", he is more certain of his visual percept than he is of the outside object. As we have seen, this attitude is rational from the standpoint of physics and physiology, because a given occurrence in the brain is capable of having a variety of causes, and where the cause is unusual common sense will be misled. It would be theoretically possible to stimulate the optic nerve artificially in just the way in which light coming from the moon stimulates it; in this case, we should have the same experience as when we "see the moon", but should be deceived as to its external source. Descartes was influenced by an argument of this sort, when he brought up the possibility of a deceitful demon. Therefore what he felt certain about was not what he had initially felt certain about, but what remained certain after an argument as to the causes of perception. This brings us to a distinction which is important, but difficult to apply: the distinction between what we in fact do not doubt, and what we should not doubt if we were completely rational. We do not in fact question the existence of the sun and moon, though perhaps we might teach ourselves to do so by a ​long course of Cartesian doubt. Even then, according to Descartes, we could not doubt that we have the experiences which we have hitherto called "seeing the sun" and "seeing the moon", although we shall need different words if we are to describe these experiences correctly.
The question arises: Why should we not doubt everything? Why should we remain convinced that we have these experiences? Might not a deceitful demon perpetually supply us with false memories? When we say "a moment ago I had the experience which I have hitherto called seeing the sun", perhaps we are deceived. In dreams we often remember things that never happened. At best, therefore, we can be sure of our present momentary experience, not of anything that happened even half a minute ago. And before we can so fix our momentary experience as to make it the basis of a philosophy, it will be past, and therefore uncertain. When Descartes said "I think", he may have had certainty; but by the time he said "therefore I am", he was relying upon memory, and may have been deceived. This line of argument leads to complete scepticism about everything. If we are to avoid such a result, we must have some new principle.
In actual fact, we start by feeling certainty about all sorts of things, and we surrender this feeling only where some definite argument has convinced us that it is liable to lead to error. When we find any class of primitive certainties which never leads to error, we retain our convictions in regard to this class. That is to say, wherever we feel initial certainty, we require an argument to make us doubt, not an argument to make us believe. We may therefore take, as the basis of our beliefs, any class of primitive certainties which cannot be shown to lead us into error. This is really what Descartes does, though he is not clear about it himself.
Moreover, when we have found an error in something of which we were previously certain, we do not as a rule abandon entirely the belief which misled us, but we seek, if we can, to modify it so that it shall no longer be demon​strably false. This is what has happened with perception. When we think we see an external object, we may be deceived by a variety of causes. There may be a mirage or a reflection; in this case, the source of the error is in the external world, and a photographic plate would be equally deceived. There may be a stimulus to the eye of the sort that makes us "see stars", or we may see little black dots owing to a disordered liver, in which case, the source of the error is in the body but not in the brain. We may have dreams in which we seem to see all sorts of things; in this case, the source of the error is in the brain. Having gradually discovered these possibilities of error, people have become somewhat wary as to the objective significance of their perceptions; but they have remained convinced that they really have the perceptions they thought they had, although the common-sense interpretation of them is sometimes at fault. Thus, while retaining the conviction that they are sure of something, they have gradually changed their view as to what it is that they are sure of. Nothing is known that tends to show error in the view that we really have the percepts we think we have, so long as we are prudent in interpreting them as signs of something external. That is the valid basis for Descartes' view that "thought" is more certain than external objects. When "thought" is taken to mean the experiences which we usually regard as percepts of objects, there are sound reasons for accepting Descartes' opinion to this extent.
Let us now take up Dr. Watson's view. We shall find, if I am not mistaken, that his position also is to a very large extent valid. That being so, we shall seek to find an intermediate opinion, accepting what seems valid and rejecting what seems doubtful in the contentions of both protagonists.
Dr. Watson's view as to what is most certain is one which is in entire accordance with common sense. All psychological matters the plain man regards as more or less open to question, but he has no doubts about his office, his morning train, the tax-collector, the weather, and the other blessings of this life. It may amuse him, in an idle hour, ​to listen to someone playing with the idea that life is a dream, or suggesting that the thoughts of the people in the train are more real than the train. But unless he is a philosophical lecturer, he does not countenance such notions in business hours. Who can imagine a clerk in an office conceiving metaphysical doubts as to the existence of his boss? Or would any railroad president regard with favour the theory that his railroad is only an idea in the minds of the shareholders? Such a view, he would say, though it is often sound as regards gold-mines, is simply silly when it comes to a railroad: anybody can see it, and can get himself run over if he wanders on the tracks under the impression that they do not exist. Belief in the unreality of matter is likely to lead to an untimely death, and that, perhaps, is the reason why this belief is so rare, since those who entertained it died out. We cannot dismiss the common-sense outlook as simply silly, since it succeeds in daily life; if we are going to reject it in part, we must be sure that we do so in favour of something equally tough as a means of coping with practical problems.
Descartes says: I think, therefore I am . Watson says: There are rats in mazes, therefore I don't think. At least, a parodist might thus sum up his philosophy. What Watson really says is more like this: (1) The most certain facts are those which are public, and can be confirmed by the testimony of a number of observers. Such facts form the basis of the physical sciences: physics, chemistry, biology, anatomy, physiology, to mention only those that are relevant to the matter in question. (2) The physical sciences are capable of affording an explanation of all the publicly observable facts about human behaviour. (3) There is no reason to suppose that there are any facts about human beings that can be known only in some other way. (4) In particular, "introspection", as a means of discovering by self-observation things that are in principle undiscoverable by observation of others, is a pernicious superstition, which must be swept away before any really sound knowledge of man becomes possible. (5) And, as a corollary, there is no reason to ​believe in the existence of "thought" as opposed to speech and other bodily behaviour.
I have numbered the above propositions, as it is important to keep them separate. On the whole, (1), (2), and (3) seem to me to be true, but (4) and (5) seem to me to be false. Behaviourists, I think, incline to the view that (4) and (5) follow from (1), (2), and (3); but this view I attribute to what I should regard as errors concerning the basis of physics. That is why it was necessary to discuss physics before coming to a decision on this question of self-observation. But let us examine each of the above propositions in turn.
(1) It is true that the facts upon which the physical sciences are based are all of them public, in the sense that many men can observe them. If a phenomenon is photographed, any number of people can inspect the photograph. If a measurement is made, not only may several people be present, but others can repeat the experiment. If the result does not confirm the first observer, the supposed fact is rejected. The publicity of physical facts is always regarded as one of the greatest assets of physics. On a common-sense basis, therefore, the first of the propositions in which we have summed up the behaviourist philosophy must be admitted.
There are, however, some very important provisos which must be mentioned. In the first place, a scientific observer is not expected to note his integral reaction to a situation, but only that part of it which experience leads him to regard as "objective", i.e. the same as the reaction of any other competent observer. This process of learning to note only "objective" features in our reaction is, as we have seen, begun in infancy; training in science only carries it further. A "good" observer does not mention what is peculiar to himself in his reaction. He does not say: "A boring speck of light danced about, causing me eye-fatigue and irritation; finally it settled at such-and-such a point." He says simply: "The reading was such-and-such". All this objectivity is a result of training and experience. One may say, in fact, ​that very few men have the "right" reaction to a scientific situation. Therefore an immense amount of theory is mixed up with what passes in science as pure observation. The nature and justification of this theory is a matter requiring investigation.
In the second place, we must not misinterpret the nature of the publicity in the case of physical phenomena. The publicity consists in the fact that a number of people make closely similar reactions at a given moment. Suppose, for example, that twelve men are told to watch a screen for the appearance of a bright light, and to say "now" when it appears. Suppose the experimenter hears them all just when he himself sees the light; then he has good reason to believe that they have each had a stimulus similar to his. But physics compels us to hold that they have had twelve separate stimuli, so that when we say they have all seen the same light we can only legitimately mean that their twelve stimuli had a common causal origin. In attributing our perceptions to a normal causal origin outside ourselves, we run a certain risk of error, since the origin may be unusual: there may be reflection or refraction on the way to the eye, there may be an unusual condition of the eye or optic nerve or brain. All these considerations give a certain very small probability that, on a given occasion, there is not such an outside cause as we suppose. If, however, a number of people concur with us, i.e. simultaneously have reactions which they attribute to an outside cause that can be identified with the one we had inferred, then the probability of error is enormously diminished. This is exactly the usual case of concurrent testimony. If twelve men, each of whom lies every other time that he speaks, independently testify that some event has occurred, the odds in favour of their all speaking the truth are 4095 to 1. The same sort of argument shows that our public senses, when confirmed by others, are probably speaking the truth, except where there are sources of collective illusion such as mirage or suggestion.
In this respect, however, there is no essential difference between matters of external observation and matters of self-​observation. Suppose, for example, that, for the first time in your life, you smell assafoetida. You say to yourself "That is a most unpleasant smell". Now unpleasantness is a matter of self-observation. It may be correlated with physiological conditions which can be observed in others, but it is certainly not identical with these, since people knew that things were pleasant and unpleasant before they knew about the physiological conditions accompanying pleasure and its opposite. Therefore when you say "That smell is unpleasant" you are noticing something that does not come into the world of physics as ordinarily understood. You are, however, a reader of psycho-analysis, and you have learned that sometimes hate is concealed love and love is concealed hate. You say to yourself, therefore: "Perhaps I really like the smell of assafoetida, but am ashamed of liking it". You therefore make your friends smell it, with the result that you soon have no friends. You then try children, and finally chimpanzees. Friends and children give verbal expression to their disgust: chimpanzees are expressive, though not verbal. All these facts lead you to state: "The smell of assafoetida is unpleasant". Although self-observation is involved, the result has the same kind of certainty, and the same kind of objective verification, as if it were one of the facts that form the empirical basis of physics.
(2) The second proposition, to the effect that the physical sciences are capable of affording an explanation of all the publicly observable facts about human behaviour, is one as to which it is possible to argue endlessly. The plain fact is that we do not yet know whether it is true or false. There is much to be said in its favour on general scientific grounds, particularly if it is put forward, not as a dogma, but as a methodological precept, a recommendation to scientific investigators as to the direction in which they are to seek for solution of their problems. But so long as much of human behaviour remains unexplained in terms of physical laws, we cannot assert dogmatically that there is no residue which is theoretically inexplicable by this method. We may say that the trend of science, so far, seems to render ​such a view improbable, but to say even so much is perhaps rash, though, for my part, I should regard it as still more rash to say that there certainly is such a residue. I propose, therefore, as a matter of argument, to admit the behaviourist position on this point, since my objections to behaviourism as an ultimate philosophy come from quite a different kind of considerations.
(3) The proposition we are now to examine may be stated as follows: "All facts that can be known about human beings are known by the same method by which the facts of physics are known". This I hold to be true, but for a reason exactly opposite to that which influences the behaviourist. I hold that the facts of physics, like those of psychology, are obtained by what is really self-observation, although common sense mistakenly supposes that it is observation of external objects. As we saw in Chapter XIII., your visual, auditory, and other percepts are all in your head, from the standpoint of physics. Therefore, when you "see the sun", it is, strictly speaking, an event in yourself that you are knowing: the inference to an external cause is more or less precarious, and is on occasion mistaken. To revert to the assafoetida: it is by a number of self-observations that you know that the smell of assafoetida is unpleasant, and it is by a number of self-observations that you know that the sun is bright and warm. There is no essential difference between the two cases. One may say that the data of psychology are those private facts which are not very directly linked with facts outside the body, while the data of physics are those private facts which have a very direct causal connection with facts outside the body. Thus physics and psychology have the same method; but this is rather what is commonly taken to be the special method of psychology than what is regarded as the method of physics. We differ from the behaviourist in assimilating physical to psychological method, rather than the opposite.
(4) Is there a source of knowledge such as is believed in by those who appeal to "introspection"? According to what we have just been saying, all knowledge rests upon ​something which might, in a sense, be called "introspection". Nevertheless, there may be some distinction to be discovered. I think myself that the only distinction of importance is in the degree of correlation with events outside the body of the observer. Suppose, for example, that a behaviourist is watching a rat in a maze, and that a friend is standing by. He says to the friend "Do you see that rat?" If the friend says yes, the behaviourist is engaged in his normal occupation of observing physical occurrences. But if the friend says no, the behaviourist exclaims, "I must give up this boot-legged whiskey". In that case, if his horror still permits him to think clearly, he will be obliged to say that in watching the imaginary rat he was engaged in introspection. There was certainly something happening, and he could still obtain knowledge by observing what was happening, provided he abstained from supposing that it had a cause outside his body. But he cannot, without outside testimony or some other extraneous information, distinguish between the "real" rat and the "imaginary" one. Thus in the case of the "real" rat also, his primary datum ought to be considered introspective, in spite of the fact that it does not seem so; for the datum in the case of the "imaginary" rat also does not seem to be merely introspective.
The real point seems to be this: some events have effects which radiate all round them, and can therefore produce reactions in a number of observers; of these, ordinary speech is an illustration. But other events produce effects which travel linearly, not spherically; of these, speech into a telephone from a sound-proof telephone box may serve as an illustration. This can be heard by only one person beside the speaker; if instead of a speaker we had an instrument at the mouthpiece, only one person could hear the sound, namely the person at the other end of the telephone. Events which happen inside a human body are like the noise in the telephone: they have effects, in the main, which travel along nerves to the brain, instead of spreading out in all directions equally. Consequently, a man can ​know a great deal about his own body which another man can only know indirectly. Another man can see the hole in my tooth, but he cannot feel my toothache. If he infers that I feel toothache, he still does not have the very same knowledge that I have; he may use the same words, but the stimulus to his use of them is different from the stimulus to mine, and I can be acutely aware of the pain which is the stimulus to my words. In all these ways a man has knowledge concerning his own body which is obtained differently from the way in which he obtains know ledge of other bodies. This peculiar knowledge is, in one sense, "introspective", though not quite in the sense that Dr. Watson denies.
(5) We come now to the real crux of the whole matter, namely to the question: Do we think? This question is very ambiguous, so long as "thinking" has not been clearly defined. Perhaps we may state the matter thus: Do we know events in us which would not be included in an absolutely complete knowledge of physics? I mean by a complete knowledge of physics a knowledge not only of physical laws, but also of what we may call geography, i.e. the distribution of energy throughout space-time. If the question is put in this way, I think it is quite clear that we do know things not included in physics. A blind man could know the whole of physics, but he could not know what things look like to people who can see, nor what is the difference between red and blue as seen. He could know all about wave-lengths, but people knew the difference between red and blue as seen before they knew anything about wave-lengths. The person who knows physics and can see knows that a certain wave-length will give him a sensation of red, but this knowledge is not part of physics. Again, we know what we mean by "pleasant" and "unpleasant", and we do not know this any better when we have discovered that pleasant things have one kind of physio logical effect and unpleasant things have another. If we did not already know what things are pleasant and what unpleasant, we could never have discovered this correlation. ​But the knowledge that certain things are pleasant and certain others unpleasant is no part of physics.
Finally, we come to imaginations, hallucinations, and dreams. In all these cases, we may suppose that there is an external stimulus, but the cerebral part of the causal chain is unusual, so that there is not in the outside world something connected with what we are imagining in the same way as in normal perception. Yet in such cases we can quite clearly know what is happening to us; we can for example, often remember our dreams. I think dreams must count as "thought", in the sense that they lie outside physics. They may be accompanied by movements, but knowledge of them is not knowledge of these movements. Indeed all knowledge as to movements of matter is inferential, and the knowledge which a scientific man should take as constituting his primary data is more like our knowledge of dreams than like our knowledge of the movements of rats or heavenly bodies. To this extent, I should say, Descartes is in the right as against Watson. Watson's position seems to rest upon naïve realism as regards the physical world, but naive realism is destroyed by what physics itself has to say concerning physical causation and the antecedents of our perceptions. On these grounds, I hold that self-observation can and does give us knowledge which is not part of physics, and that there is no reason to deny the reality of "thought".