Philosophy

by Bertrand Russell

After this excursion into the realm of desire, we can now return to “knowledge”, which, as we saw, is a term correlative to “desire”, and applicable to another feature of the same kind of activity. We may say, broadly, that a response to a stimulus of the kind involving desire in the above sense shows “knowledge” if it leads by the quickest or easiest route to the state of affairs which, in the above sense, is behaviouristically the object of desire. Knowledge is thus a matter of degree: the rat, during its progressive improvements in the maze, is gradually acquiring more and more knowledge. Its “intelligence quotient”, so far as that particular task is concerned, will be the ratio of the time it took on the first trial to the time it takes now to get out of the maze. Another point, if our definition of knowledge is accepted, is, that there is no such thing as purely contemplative knowledge: knowledge exists only in relation to the satisfaction of desire, or, as we say, in the capacity to choose the right means to achieve our ends.

But can such a definition as the above really stand? Does it represent at all the sort of thing that would commonly be called knowledge? I think it does in the main, but there is need of some discussion to make this clear.

In some cases, the definition is obviously applicable. These are the cases that are analogous to the rat in the maze, the consideration of which led us to our definition. Do you “know” the way from Trafalgar Square to St. Pancras? Yes, if you can walk it without taking any wrong turnings. In practice, you can give verbal proof of such knowledge, without actually having to walk the distance; but that depends upon the correlation of names with streets, and is part of the process of substituting words for things. There may, it is true, come doubtful cases. I was once on a bus in Whitehall, and my neighbour asked “What street is this?” I answered him, not without surprise at his ignorance. He then said, “What building is that?” and I replied “The Foreign Office”. To this he retorted, “but I thought the Foreign Office was in Downing Street”. This time, it was his knowledge that surprised me. Should we say that he knew where the Foreign Office is? The answer is yes or no according to his purpose. From the point of view of sending a letter to it, he knew; from the point of view of walking to it, he did not know. He had, in fact, been a British Consul in South America, and was in London for the first time.

But now let us come to cases less obviously within the scope of our definition. The reader “knows” that Columbus crossed the ocean in 1492. What do we mean by saying that he “knows” this? We mean, no doubt, primarily that writing down this statement is the way to pass examinations, which is just as useful to us as getting out of the maze is to the rat. But we do not mean only this. There is historical evidence of the fact, at least I suppose there is. The historical evidence consists of printed books and manuscripts. Certain rules have been developed by historians as to the conditions in which statements in books or manuscripts may be accepted as true, and the evidence in our case is (I presume) in accordance with these rules. Historical facts often have importance in the present; for example, wills, or laws not yet repealed. The rules for weighing historical evidence are such as will, in general bring out self-consistent results. Two results are self-consistent when, in relation to a desire to which both are relevant, they enjoin the same action, or actions which can form part of the one movement towards the goal. At Coton, near Cambridge, there is (or was in my time) a signpost with two arms pointing in diametrically opposite directions, and each arm said “To Cambridge”. This was a perfect example of self-contradiction, since the two arms made statements representing exactly opposite actions. And this case illustrates why self-contradiction is to be avoided. But the avoidance of self-contradiction makes great demands upon us; Hegel and Bradley imagined that we could know the nature of the universe by means of this principle alone. In this they were pretty certainly mistaken, but nevertheless a great deal of our “knowledge” depends upon this principle to a greater or less extent.

Most of our knowledge is like that in a cookery book, maxims to be followed when occasion arises, but not useful at every moment of every day. Since knowledge may be useful at any time, we get gradually, through conditioning, a general desire for knowledge. The learned man who is helpless in practical affairs is analogous to the miser, in that he has become absorbed in a means. It should be observed, also, that knowledge is neutral as among different purposes. If you know that arsenic is a poison, that enables you equally to avoid it if you wish to remain in health, and to take it if you wish to commit suicide. You cannot judge from a man’s conduct in relation to arsenic whether he knows that it is a poison or not, unless you know his desires. He may be tired of life, but avoid arsenic because he has been told that it is a good medicine; in this case, his avoidance of it is evidence of lack of knowledge.

But to return to Columbus: surely, the reader will say, Columbus really did cross the Atlantic in 1492, and that is why we call this statement “knowledge”. This is the definition of “truth” as “correspondence with fact”. I think there is an important element of correctness in this definition, but it is an element to be elicited at a later stage, after we have discussed the physical world. And it has the defect—as pragmatists have urged—that there seems no way of getting at “facts” and comparing them with our beliefs: all that we ever reach consists of other beliefs. I do not offer our present behaviouristic and pragmatic definition of “knowledge” as the only possible one, but I offer it as the one to which we are led if we wish to regard knowledge as something causally important, to be exemplified in our reactions to stimuli. This is the appropriate point of view when we are studying man from without, as we have been doing hitherto.

There is, however, within the behaviourist philosophy, one important addition to be made to our definition. We began this chapter with sensitivity, but we went on to the consideration of learned reactions, where the learning depended upon association. But there is another sort of learning—at least it is prima facie another sort—which consists of increase of sensitivity. All sensitivity in animals and human beings must count as a sort of knowledge; that is to say, if an animal behaves, in the presence of a stimulus of a certain kind, as it would not behave in the absence of that stimulus then, in an important sense, it has “knowledge” as regards the stimulus. Now it appears that practice—e.g. in music—very greatly increases sensitivity. We learn to react differently to stimuli which only differ sightly; what is more, we learn to react to differences. A violin-player can react with great precision to an interval of a fifth; if the interval is very slightly greater or less, his behaviour in tuning is influenced by the difference from a fifth. And as we have already had occasion to notice, we become, through practice, increasingly sensitive to form. All this increased sensitivity must count as increase of knowledge.

But in saying this we are not saying anything inconsistent with our earlier definition of knowledge. Sensitivity is essential to choosing the right reaction in many cases. To take the cookery-book again; when it says “take a pinch of salt”, a good cook knows how much to take, which is an instance of sensitivity. Accurate scientific observation, which is of great practical importance, depends upon sensitivity. And so do many of our practical dealings with other people: if we cannot “feel” their moods, we shall be always getting at cross purposes.

The extent to which sensitivity is improved by practice is astonishing. Town-bred people do not know whether the weather is warm or cold until they read the weather reports in the paper. An entomologist perceives vastly more beetles in the course of a country walk than other people do. The subtlety with which connoisseurs can distinguish among wines and cigars is the despair of youths who wish to become men of the world. Whether this increase of sensitivity can be accounted for by the law of association, I do not know. In many cases, probably, it can, but I think sensitiveness to form, which is the essential element in the more difficult forms of abstract thought as well as in many other matters, cannot be regarded as derivative from the law of association, but is more analogous to the development of a new sense. I should therefore include improvement in sensitivity as an independent element in the advancement of knowledge. But I do so with some hesitation.

The above discussion does not pretend to cover the whole of the ground that has to be covered in discussing the definition of “knowledge”. There are other points of view, which are also necessary to a complete consideration of the question. But these must wait until, after considering the physical world, we come to the discussion of man as viewed from within.