# An Outline of Philosophy/Chapter 2

PART I
MAN FROM WITHOUT
If our scientific knowledge were full and complete, we should understand ourselves and the world and our relation to the world. As it is, our understanding of all three is fragmentary. For the present, it is the third question, that of our relation to the world, that I wish to consider, because this brings us nearest to the problems of philosophy. We shall find that it will lead us back to the other two questions, as to the world and as to ourselves, but that we shall understand both these better if we have considered first how the world acts upon us and how we act upon the world.
There are a number of sciences which deal with Man. We may deal with him in natural history, as one among the animals, having a certain place in evolution, and related to other animals in ascertainable ways. We may deal with him in physiology, as a structure capable of performing certain functions, and reacting to the environment in ways of which some, at least, can be explained by chemistry. We may study him in sociology, as a unit in various organisms, such as the family and the state. And we may study him, in psychology, as he appears to himself. This last gives what we may call an internal view of man, as opposed to the other three, which give an external view. That is to say, in psychology we use data which can only be obtained when the observer and the observed are the same person, whereas in the other ways of studying Man all our data can be obtained by observing other people. There are different ways of interpreting this distinction, and different views of its ​importance, but there can be no doubt that there is such a distinction. We can remember our own dreams, whereas we cannot know the dreams of others unless they tell us about them. We know when we have toothache, when our food tastes too salt, when we are remembering some past occurrence, and so on. All these events in our lives other people cannot know in the same direct way. In this sense, we all have an inner life, open to our own inspection but to no one else's. This is no doubt the source of the traditional distinction of mind and body: the body was supposed to be that part of us which others could observe, and the mind that part which was private to ourselves. The importance of the distinction has been called in question in recent times, and I do not myself believe that it has any fundamental philosophical significance. But historically it has played a dominant part in determining the conceptions from which men set out when they began to philosophise, and on this account, if on no other, it deserves to be borne in mind.
Knowledge, traditionally, has been viewed from within, as something which we observe in ourselves rather than as something which we can see others displaying. When I say that it has been so viewed, I mean that this has been the practice of philosophers; in ordinary life, people have been more objective. In ordinary life, knowledge is something which can be tested by examinations, that is to say, it consists in a certain kind of response to a certain kind of stimulus. This objective way of viewing knowledge is, to my mind, much more fruitful than the way which has been customary in philosophy. I mean that, if we wish to give a definition of "knowing", we ought to define it as a manner of reacting to the environment, not as involving something (a "state of mind") which only the person who has the knowledge can observe. It is because I hold this view that I think it best to begin with Man and his environment, rather than with those matters in which the observer and the observed must be the same person. Knowing, as I view it, is a characteristic which may be displayed in our reactions ​to our environment; it is therefore necessary first of all to consider the nature of these reactions as they appear in science.
Let us take some everyday situation. Suppose you are watching a race, and at the appropriate moment you say, "They're off". This exclamation is a reaction to the environment, and is taken to show knowledge if it is made at the same time as others make it. Now let us consider what has been really happening, according to science. The complication of what has happened is almost incredible. It may conveniently be divided into four stages: first, what happened in the outside world between the runners and your eyes; secondly, what happened in your body from your eyes to your brain; thirdly, what happened in your brain; fourthly, what happened in your body from your brain to the movements of your throat and tongue which constituted your exclamation. Of these four stages, the first belongs to physics, and is dealt with in the main by the theory of light; the second and fourth belong to physiology; the third, though it should theoretically also belong to physiology, belongs in fact rather to psychology, owing to our lack of knowledge as to the brain. The third stage embodies the results of experience and learning. It is responsible for the fact that you speak, which an animal would not do, and that you speak English, which a Frenchman would not do. This immensely complicated occurrence is, nevertheless, about the simplest example of knowledge that could possibly be given.
For the moment, let us leave on one side the part of this process which happens in the outside world and belongs to physics. I shall have much to say about it later, but what has to be said is not altogether easy, and we will take less abstruse matters first. I will merely observe that the event which we are said to perceive, namely, the runners starting, is separated by a longer or shorter chain of events from the event which happens at the surface of our eyes. It is this last that is what is called the "stimulus". Thus the event that we are said to perceive when we see is not the stimulus, ​but an anterior event related to it in a way that requires investigation. The same applies to hearing and smell, but not to touch or to perception of states of our own body. In these cases, the first of the above four stages is absent. It is clear that, in the case of sight, hearing and smell, there must be a certain relation between the stimulus and the event said to be perceived, but we will not now consider what this relation must be. We will consider, rather, the second, third, and fourth stages in an act of perceptive knowledge. This is the more legitimate as these stages always exist, whereas the first is confined to certain senses.
The second stage is that which proceeds from the sense-organ to the brain. It is not necessary for our purposes to consider exactly what goes on during this journey. A purely physical event—the stimulus—happens at the boundary of the body, and has a series of effects which travel along the afferent nerves to the brain. If the stimulus is light, it must fall on the eye to produce the characteristic effects; no doubt light falling on other parts of the body has effects, but they are not those that distinguish vision. Similarly, if the stimulus is sound, it must fall on the ear. A sense-organ, like a photographic plate, is responsive to stimuli of a certain sort: light falling on the eye has effects which are different for different wave-lengths, intensities, and directions. When the events in the eye due to incident light have taken place, they are followed by events in the optic nerve, leading at last to some occurrence in the brain—an occurrence which varies with the stimulus. The occurrence in the brain must be different for different stimuli in all cases where we can perceive differences. Red and yellow, for instance, are distinguishable in perception; therefore the occurrences along the optic nerve and in the brain must have a different character when caused by red light from what they have when caused by yellow light. But when two shades of colour are so similar that they can only be distinguished by delicate instruments, not by perception, we cannot be sure that they cause occurrences of different characters in the optic nerve and brain.
​When the disturbance has reached the brain, it may or may not cause a characteristic set of events in the brain. If it does not, we shall not be what is called "conscious” of it. For to be "conscious" of seeing yellow, whatever else it may be, must certainly involve some kind of cerebral reaction to the message brought by the optic nerve. It may be assumed that the great majority of messages brought to the brain by the afferent nerves never secure any attention at all—they are like letters to a government office which remain unanswered. The things in the margin of the field of vision, unless they are in some way interesting, are usually unnoticed; if they are noticed, they are brought into the centre of the field of vision unless we make a deliberate effort to prevent this from occurring. ‘These things are visible, in the sense that we could be aware of them if we chose, without any change in our physical environment or in our sense- organs; that is to say, only a cerebral change is required to enable them to cause a reaction. But usually they do not provoke any reaction; life would be altogether too wearing if we had to be always reacting to everything in the field of vision. Where there is no reaction, the second stage completes the process, and the third and fourth stages do not arise. In that case, there has been nothing that could be called "perception" connected with the stimulus in question.
To us, however, the interesting case is that in which the process continues. In this case there is first a process in the brain, of which the nature is as yet conjectural, which travels from the centre appropriate to the sense in question to a motor centre. From there there is a process which travels along an efferent nerve, and finally results in a muscular event causing some bodily movement. In our illustration of the man hing the beginning of a race, a process travels from the part of the brain concerned with sight to the part concerned with speech; this is what we called the third stage. Then a process travels along the efferent nerves and brings about the movements which constitute saying "They're off"; this is what we called the fourth stage.
​Unless all four stages exist, there is nothing that can be called "knowledge". And even when they are all present, various further conditions must be satisfied if there is to be "knowledge". But these observations are premature, and we must return to the analysis of our third and fourth stages.
The third stage is of two sorts, according as we are concerned with a reflex or with a "learned reaction", as Dr. Watson calls it. In the case of a reflex, if it is complete at birth, a new-born infant or animal has a brain so constituted that, without the need of any previous experience, there is a connection between a certain process in the afferent nerves and a certain other process in the efferent nerves. A good example of a reflex is sneezing. A certain kind of tickling in the nose produces a fairly violent movement having a very definite character, and this connection exists already in the youngest infants. Learned reactions, on the other hand, are such as only occur because of the effect of previous occurrences in the brain. One might illustrate by an analogy which, however, would be misleading if pressed. Imagine a desert in which no rain has ever fallen, and suppose that at last a thunderstorm occurs in it; then the course taken by the water will correspond to a reflex. But if rain continues to fall frequently, it will form watercourses and river valleys; when this has occurred, the water runs away along pre-formed channels, which are attributable to the past "experience" of the region. This corresponds to "learned reactions". One of the most notable examples of learned reactions is speech: we speak because we have learned a certain language, not because our brain had originally any tendency to react in just that way. Perhaps all knowledge, certainly nearly all, is dependent upon learned reactions, i.e. upon connections in the brain which are not part of man's congenital equipment but are the result of events which have happened to him.
To distinguish between learned and unlearned responses is not always an easy task. It cannot be assumed that responses which are absent during the first weeks of life are all learned. To take the most obvious instance: sexual ​responses change their character to a greater or less extent at puberty, as a result of changes in the ductless glands, not as a result of experience. But this instance does not stand alone: as the body grows and develops, new modes of response come into play, modified, no doubt, by experience, but not wholly due to it. For example: a new-born baby cannot run, and therefore does not run away from what is terrifying, as an older child does. The older child has learned to run, but has not necessarily learned to run away; the stimulus in learning to run may have never been a terrifying object. It would therefore be a fallacy to suppose that we can distinguish between learned and unlearned responses by observing what a new-born infant does, since reflexes may come into play at a later stage. Conversely, some things which a child does at birth may have been learned, when they are such as it could have done in the womb—for example, a certain amount of kicking and stretching. The whole distinction between learned and unlearned responses, therefore, is not so definite as we could wish. At the two extremes we get clear cases, such as sneezing on the one hand and speaking on the other; but there are intermediate forms of behaviour which are more difficult to classify.
This is not denied even by those who attach most importance to the distinction between learned and unlearned responses. In Dr. Watson's Behaviourism (p. 103), there is a "Summary of Unlearned Equipment", which ends with the following paragraph:
"Other activities appear at a later stage—such as blinking, reaching, handling, handedness, crawling, standing, sitting-up, walking, running, jumping. In the great majority of these later activities it is difficult to say how much of the act as a whole is due to training or conditioning. A considerable part is unquestionably due to the growth changes in structure, and the remainder is due to training and conditioning." (Watson's italics.)
It is not possible to make a logically sharp distinction in this matter; in certain cases we have to be satisfied with ​something less exact. For example, we might say that those developments which are merely due to normal growth are to count as unlearned, while those which depend upon special circumstances in the individual biography are to count as learned. But take, say, muscular development: this will not take place normally unless the muscles are used, and if they are used they are bound to learn some of the skill which is appropriate to them. And some things which must certainly count as learned, such as focussing with the eyes, depend upon circumstances which are normal and must be present in the case of every child that is not blind. The whole distinction, therefore, is one of degree rather than of kind; nevertheless it is valuable.
The value of the distinction between learned and unlearned reactions is connected with the laws of learning, to which we shall come in the next chapter. Experience modifies behaviour according to certain laws, and we may say that a learned reaction is one in the formation of which these laws have played a part. For example: children are frightened of loud noises from birth, but are not at first frightened of dogs; after they have heard a dog barking loudly, they may become frightened of dogs, which is a learned reaction. If we knew enough about the brain, we could make the distinction precise, by saying that learned reactions are those depending upon modifications of the brain other than mere growth. But as it is, we have to judge by observations of bodily behaviour, and the accompanying modifications in the brain are assumed on a basis of theory rather than actually observed.
The essential points, for our purposes, are comparatively simple. Man or any other animal, at birth, is such as to respond to certain stimuli in certain specific ways, i.e. by certain kinds of bodily movements; as he grows, these ways of responding change, partly as the mere result of developing structure, partly in consequence of events in his biography. The latter influence proceeds according to certain laws, which we shall consider, since they have much to do with the genesis of "knowledge".
​But—the indignant reader may be exclaiming—knowing something is not a bodily movement, but a state of mind, and yet you talk to us about sneezing and such matters. I must ask the indignant reader's patience. He "knows" that he has states of mind, and that his knowing is itself a state of mind. I do not deny that he has states of mind, but I ask two questions: First, what sort of thing are they? Secondly, what evidence can he give me that he knows about them? The first question he may find very difficult; and if he wants, in his answer, to show that states of mind are something of a sort totally different from bodily movements, he will have to tell me also what bodily movements are, which will plunge him into the most abstruse parts of physics. All this I propose to consider later on, and then I hope the indignant reader will be appeased. As to the second question, namely, what evidence of his knowledge another man can give me, it is clear that he must depend upon speech or writing, i.e. in either case upon bodily movements. Therefore whatever knowledge may be to the knower, as a social phenomenon it is something displayed in bodily movements. For the present I am deliberately postponing the question of what knowledge is to the knower, and confining myself to what it is for the external observer. And for him, necessarily, it is something shown by bodily movements made in answer to stimuli—more specifically, to examination questions. What else it may be I shall consider at a later stage.
However we may subsequently add to our present account by considering how knowledge appears to the knower, that will not invalidate anything that we may arrive at by considering how knowledge appears to the external observer. And there is something which it is important to realise, namely, that we are concerned with a process in which the environment first acts upon a man, and then he reacts upon the environment. This process has to be considered as a whole if we are to discuss what knowledge is. The older view would have been that the effect of the environment upon us might constitute a certain kind of ​knowledge (perception), while our reaction to the environment constituted volition. These were, in each case, "mental" occurrences, and their connection with nerves and brain remained entirely mysterious. I think the mystery can be eliminated, and the subject removed from the realm of guesswork, by starting with the whole cycle from stimulus to bodily movement. In this way, knowing becomes something active, not something contemplative. Knowing and willing, in fact, are merely aspects of the one cycle, which must be considered in its entirety if it is to be rightly understood.
A few words must be said about the human body as a mechanism. It is an inconceivably complicated mechanism, and some men of science think that it is not explicable in terms of physics and chemistry, but is regulated by some "vital principle" which makes its laws different from those of dead matter. These men are called "vitalists". I do not myself see any reason to accept their view, but at the same time our knowledge is not sufficient to enable us to reject it definitely. What we can say is that their case is not proved, and that the opposite view is, scientifically, a more fruitful working hypothesis. It is better to look for physical and chemical explanations where we can, since we know of many processes in the human body which can be accounted for in this way, and of none which certainly cannot. To invoke a "vital principle" is to give an excuse for laziness, when perhaps more diligent research would have enabled us to do without it. I shall therefore assume, as a working hypothesis, that the human body acts according to the same laws of physics and chemistry as those which govern dead matter, and that it differs from dead matter, not by its laws, but by the extraordinary complexity of its structure.
The movements of the human body may, none the less, be divided into two classes, which we may call respectively "mechanical" and "vital". As an example of the former, I should give the movement of a man falling from a cliff into the sea. To explain this, in its broad features, it is ​not necessary to take account of the fact that the man is alive; his centre of gravity moves exactly as that of a stone would move. But when a man climbs up a cliff, he does something that dead matter of the same shape and weight would never do; this is a "vital" movement. There is in the human body a lot of stored chemical energy in more or less unstable equilibrium; a very small stimulus can release this energy, and cause a considerable amount of bodily movement. The situation is analogous to that of a large rock delicately balanced on the top of a conical mountain: a tiny shove may send it thundering down into the valley, in one direction or another according to the direction of the shove. So if you say to a man "Your house is on fire", he will start running; although the stimulus contained very little energy, his expenditure of energy may be tremendous. He increases the available energy by panting, which makes his body burn up faster and increases the energy due to combustion; this is just like opening the draught in a furnace. "Vital" movements are those that use up this energy which is in unstable equilibrium. It is they alone that concern the bio-chemist, the physiologist, and the psychologist. The others, being just like the movements of dead matter, may be ignored when we are specially concerned with the study of Man.
Vital movements have a stimulus which may be inside or outside the body, or both at once. Hunger is a stimulus inside the body, but hunger combined with the sight of good food is a double stimulus, both internal and external. The effect of a stimulus may be, in theory, according to the laws of physics and chemistry, but in most cases this is, at present, no more than a pious opinion. What we know from observation is that behaviour is modified by experience, that is to say, that if similar stimuli are repeated at intervals they produce gradually changing reactions. When a bus conductor says "Fares, please", a very young child has no reaction, an older child gradually learns to look for pennies, and, if a male, ultimately acquires the power of producing the requisite sum on demand without conscious effort. The ​way in which our reactions change with experience is a distinctive characteristic of animals; moreover it is more marked in the higher than in the lower animals, and most marked of all in Man. It is a matter intimately connected with "intelligence", and must be investigated before we can understand what constitutes knowledge from the standpoint of the external observer; we shall be concerned with it at length in the next chapter.
Speaking broadly, the actions of all living things are such as tend to biological survival, i.e. to the leaving of a numerous progeny. But when we descend to the lowest organisms, which have hardly anything that can be called individuality, and reproduce themselves by fission, it is possible to take a simpler view. Living matter, within limits, has the chemical peculiarity of being self-perpetuating, and of conferring its own chemical composition upon other matter composed of the right elements. One spore falling into a stagnant pond may produce millions of minute vegetable organisms; these, in turn, enable one small animal to have myriads of descendants living on the small plants; these, in turn, provide life for larger animals, newts, tad poles, fishes, etc. In the end there is enormously more protoplasm in that region than there was to begin with. This is no doubt explicable as a result of the chemical constitution of living matter. But this purely chemical self-preservation and collective growth is at the bottom of every thing else that characterises the behaviour of living things. Every living thing is a sort of imperialist, seeking to transform as much as possible of its environment into itself and its seed. The distinction between self and posterity is one which does not exist in a developed form in asexual uni cellular organisms; many things, even in human life, can only be completely understood by forgetting it. We may regard the whole of evolution as flowing from this "chemical imperialism" of living matter. Of this, Man is only the last example (so far). He transforms the surface of the globe by irrigation, cultivation, mining, quarrying, making canals and railways, breeding certain animals, and destroying ​others; and when we ask ourselves, from the standpoint of an outside observer, what is the end achieved by all these activities, we find that it can be summed up in one very simple formula: to transform as much as possible of the matter on the earth's surface into human bodies. Domestication of animals, agriculture, commerce, industrialism have been stages in this process. When we compare the human population of the globe with that of other large animals and also with that of former times, we see that "chemical imperialism" has been, in fact, the main end to which human intelligence has been devoted. Perhaps intelligence is reaching the point where it can conceive worthier ends, concerned with the quality rather than the quantity of human life. But as yet such intelligence is confined to minorities, and does not control the great movements of human affairs. Whether this will ever be changed I do not venture to predict. And in pursuing the simple purpose of maximising the amount of human life, we have at any rate the consolation of feeling at one with the whole movement of living things from their earliest origin on this planet.