The Existence Of Other People

The previous considerations depend on supposing that there are other people besides ourselves.

People exist to me as they are represented by certain sense-data such as when I:

• see them or
• hear them

Only these phsyical data tell me that they exist and are not in a dream.

Thus, we cannot appeal to the testimony of other people on the existence of objects.

Thus from our own purely private experiences, we find characteristics which show that there are other experiences than our own private experiences in the world.

We can only prove the existence of things through ourselves and our experiences.

The world consists of myself, my thoughts, feelings, and sensations. Everything else is mere fancy.

In dreams, a very complicated world might be present. Yet on waking, we find it was a delusion. The sense-data in the dream do not correspond with physical objects inferred by our sense-data.

It is possible to find physical causes for the sense-data in dreams.

• A door banging, for instance, may cause us to dream of a naval engagement.
• But there is no actual naval battle that corresponds to the naval battle in our dream.

It is logical to believe that life is a dream in which we ourselves create all the objects that come before us. But there is no reason to suppose that it is true.

It is, in fact, a less simple hypothesis, viewed as a means of accounting for the facts of our own life, than the common-sense hypothesis that there really are objects independent of us, whose action on us causes our sensations.

The way in which simplicity comes in from supposing that there really are physical objects is easily seen.

If the cat appears at one moment in one part of the room, and at another in another part, it is natural to suppose that it has moved from the one to the other, passing over a series of intermediate positions.

But if it is merely a set of sense-data, it cannot have ever been in any place where I did not see it; thus we shall have to suppose that it did not exist at all while I was not looking, but suddenly sprang into being in a new place.

If the cat exists whether I see it or not, we can understand from our own experience how it gets hungry between one meal and the next; but if it does not exist when I am not seeing it, it seems odd that appetite should grow during non-existence as fast as during existence.

If the cat consists only of sense-data, it cannot be hungry, since no hunger but my own can be a sense-datum to me.

Thus the behaviour of the sense-data which represent the cat to me, though it seems quite natural when regarded as an expression of hunger, becomes utterly inexplicable when regarded as mere movements and changes of patches of colour, which are as incapable of hunger as a triangle is of playing football.

But the difficulty in the case of the cat is nothing compared to the difficulty in the case of human beings. When human beings speak—that is, when we hear certain noises which we associate with ideas, and simultaneously see certain motions of lips and expressions of face—it is very difficult to suppose that what we hear is not the expression of a thought, as we know it would be if we emitted the same sounds.

Of course similar things happen in dreams, where we are mistaken as to the existence of other people.

But dreams are more or less suggested by what we call waking life, and are capable of being more or less accounted for on scientific principles if we assume that there really is a physical world.

Thus every principle of simplicity urges us to adopt the natural view, that there really are objects other than ourselves and our sense-data which have an existence not dependent upon our perceiving them.

It is not by argument that we originally come by our belief in an independent external world. We find this belief ready in ourselves as soon as we begin to reflect: it is what may be called an instinctive belief.

We should never have been led to question this belief but for the fact that, at any rate in the case of sight, it seems as if the sense-datum itself were instinctively believed to be the independent object, whereas argument shows that the object cannot be identical with the sense-datum.

This discovery, however—which is not at all paradoxical in the case of taste and smell and sound, and only slightly so in the case of touch—leaves undiminished our instinctive belief that there are objects corresponding to our sense-data.

Since this belief does not lead to any difficulties, but on the contrary tends to simplify and systematize our account of our experiences, there seems no good reason for rejecting it.

We may therefore admit—though with a slight doubt derived from dreams—that the external world does really exist, and is not wholly dependent for its existence upon our continuing to perceive it.

All knowledge must be built up upon our instinctive beliefs. If these are rejected, nothing is left.

But among our instinctive beliefs some are much stronger than others. Many have, by habit and association, become entangled with other beliefs, not really instinctive, but falsely supposed to be part of what is believed instinctively.

Philosophy should show us the hierarchy of our instinctive beliefs, beginning with those we hold most strongly, and presenting each as much isolated and as free from irrelevant additions as possible.

It should take care to show that, in the form in which they are finally set forth, our instinctive beliefs do not clash, but form a harmonious system.

There can never be any reason for rejecting one instinctive belief except that it clashes with others.

Thus, if they are found to harmonize, the whole system becomes worthy of acceptance.

All or any of our beliefs might be mistaken. Therefore all should be held with at least some slight element of doubt.

But we cannot have reason to reject a belief except on the ground of some other belief.

Hence, by organizing our instinctive beliefs and their consequences, by considering which among them is most possible, if necessary, to modify or abandon, we can arrive, on the basis of accepting as our sole data what we instinctively believe, at an orderly systematic organization of our knowledge, in which, though the possibility of error remains, its likelihood is diminished by the interrelation of the parts and by the critical scrutiny which has preceded acquiescence.

This function, at least, philosophy can perform.

Most philosophers, rightly or wrongly, believe that philosophy can do much more than this—that it can give us knowledge, not otherwise attainable, concerning the universe as a whole, and concerning the nature of ultimate reality.

Whether this be the case or not, the more modest function we have spoken of can certainly be performed by philosophy, and certainly suffices, for those who have once begun to doubt the adequacy of common sense, to justify the arduous and difficult labours that philosophical problems involve.