Part 6

Now these philosophers may be right in holding this. It may, perhaps, be true that, in this sense, my own observations give me no reason whatever for believing that any other person ever has or will perceive anything like or unlike what I perceive. But I think it is desirable we should realise how paradoxical are the consequences which must be admitted, if this is true. It must then be admitted that the very large part of our knowledge, which we suppose to have some basis in experience, is by no means based upon experience, in the sense, and to the extent, which we suppose. We do for instance, commonly suppose that there is some basis in experience for the assertion that some people, whom we call Germans, use one set of words to express much the same meaning which we express by using a different set of words. But, if this view be correct, we must admit that no person's experience gives him any reason whatever for supposing that, when he hears certain words, any one else has ever heard or thought of the same words, or meant anything by them. The view admits, indeed, that I do know that when I hear certain words, somebody else has generally had thoughts more or less similar to those which I suppose him to have had: but it denies that my own observations could ever give me the least reason for supposing that this is so. It admits that my own observations may give me reason for supposing that _if_ anyone has ever had perceptions like mine in some respects, he will also have had other perceptions like others of mine: but it denies that they give me any reason for supposing that any one else has had a perception like one of mine. It admits that my own observations may give me reason for supposing that certain perceptions and thoughts in _one_ person (_if_ they exist) will be followed or preceded by certain other perceptions and thoughts in that person: but it denies that they give me any reason whatever for _any_ similar generalisation concerning the connection of a certain kind of perception in one person with a certain kind of perception in another. It admits that I should not have certain perceptions, which I do have, unless someone else had had certain other perceptions; but it denies that my own observations can give me any reason for saying so--for saying that I should not have had this perception, unless someone else had had that. No observations of mine, it holds, can ever render it probable that such a generalisation is true; no observation of mine can ever confirm or verify such a generalisation. If we are to say that any such generalisation whatever is based upon observation, we can only mean, what Reid means, that it is based on a series of assumptions. When I observe this particular thing, I assume that _that_ particular thing, which I do not observe, exists; when I observe another particular thing, I again assume that a second particular thing, which I do not observe, exists; when I observe a third particular thing, I again assume that a third particular thing, which I do not observe, exists. These assumed facts--the assumed fact that one observation of mine is accompanied by the existence of one particular kind of thing, and that another observation of mine is accompanied by the existence of a different particular kind of thing, will then give me a reason for different generalisations concerning the connection of different perceptions of mine with different external objects--objects which I do not perceive. But (it is maintained) nothing but a mass of such assumptions will give me a reason for any such generalisation.

Now I think it must be admitted that there is something paradoxical in such a view. I think it may be admitted that, in holding it, the philosopher of Common Sense departs from Common Sense at least as far in one direction as his opponents had done in another. But I think that there is some excuse for those who hold it: I think that, in one respect, they are more in the right than those who do not hold it--than those who hold that my own observations do give me a reason for believing in the existence of other people. For those who hold that my observations do give me a reason, have, I believe, universally supposed that the reason lies in a part of my observations, in which no such reason is to be found. This is why I have chosen to ask the question: _What_ reason do my observations give me for believing that any other person has any particular perceptions or beliefs? I wish to consider _which_ among the things which I observe will give such a reason. For this is a question to which no answer, that I have ever seen, appears to me to be correct. Those who have asked it have, so far as I know, answered it _either_ by denying that my observations give me any reason _or_ by pointing to a part of my observations, which, as it seems to me, really do give none. Those who deny are, it seems to me, right in holding that the reason given by those who affirm is no reason. And their correct opinion on this point will, I think, partly serve to explain their denial. They have supposed that if our observations give us any reason at all for asserting the existence of other people, that reason must lie where it has been supposed to lie by those who hold that they do give a reason. And then, finding that this assigned reason is no reason, they have assumed that there is no other.

I am proposing then to ask: Which among the observations, which I make, and which (as we commonly suppose) are similar in kind to those which all or almost all men make, will give a reason for supposing that the existence of any of them is generally connected with the existence of certain kinds of perception or belief in other people? And in order to answer this question, it is obvious we must first consider two others. We must consider, in the first place: Of what nature must observations be, if they are to give a reason for any generalisation asserting that the existence of one kind of thing is generally connected with that of another? And we must consider in the second place: What kinds of things do we observe?

Now to the first of these questions I am not going to attempt to give a complete answer. The question concerning the rules of Inductive Logic, which is the question at issue, is an immensely difficult and intricate question. And I am not going to attempt to say, what kind of observations are _sufficient_ to justify a generalisation. But it is comparatively easy to point out that a certain kind of observations are _necessary_ to justify a generalisation: and this is all that I propose to do. I wish to point out certain conditions which observations must satisfy, if they are to justify a generalisation; without in any way implying that all observations which do satisfy these conditions, _will_ justify a generalisation. The conditions, I shall mention, are ones which are certainly _not_ sufficient to justify a generalisation; but they are, I think, conditions, without which no generalisation can be justified. If a particular kind of observations do _not_ satisfy these conditions, we can say with certainty that those observations give us _no_ reason for believing in the existence of other people; though, with regard to observations which _do_ satisfy them, we shall only be able to say that they _may_ give a reason.

What conditions, then, must observations satisfy, if they are to justify a generalisation? Let us suppose that the generalisation to be justified is one which asserts that the existence of a kind of object, which we will call A, is generally preceded, accompanied, or followed by the existence of a kind of object, which we call B. A, for instance, might be the hearing of a certain word by one person, and B the thought of that which we call the meaning of the word, in another person; and the generalisation to be justified might be that when one person hears a word, not spoken by himself, someone else has generally thought of the meaning of that word. What must I have observed, if the generalisation that the existence of A is generally preceded by the existence of B, is to be justified by my observations? One first point, I think, is plain. I must have observed both some object, which is in some respects like A, and which I will call _α_, and also some object in some respects like B which I will call _β_: I must have observed both _α_ and _β_, and also I must have observed _β_ preceding _α._ This, at least, I must have observed. But I do not pretend to say _how_ like _α_ and _β_ must be to A and B; nor do I pretend to say how often I must have observed _β_ preceding _α_, although it is generally held that I must have observed this more than once. These are questions, which would have to be discussed if we were trying to discover what observations were _sufficient_ to justify the generalisation that the existence of A is generally preceded by that of B. But I am only trying to lay down the minimum which is _necessary_ to justify this generalisation; and therefore I am content to say that we must have observed something more or less like B preceding something more or less like A, at least once.

But there is yet another minimum condition. If my observation of _β_ preceding _α_ is to justify the generalisation that the _existence_ of A is generally preceded by the _existence_ of B, it is plain, I think, that both the _β_ and the _α,_ which I observed, must have _existed_ or been _real_; and that also the existence of _β_ must _really_ have preceded that of _α_. It is plain that if, when I observed _α_ and _β_, _α_ existed but _β_ did not, this observation could give me no reason to suppose that on another occasion when A existed, _β_ _would_ exist. Or again, if, when I observed _β_ preceding _α_, both _β_ and _α_ existed, but the existence of _β_ did not _really_ precede that of α, but, on the contrary, followed it, this observation could certainly give me no reason to suppose that, in general, the existence of A was _preceded_ by the existence of B. Indeed this condition that what is observed must have been _real_ might be said to be included in the very meaning of the word "observation." We should, in this connection, say that we had _not_ observed _β_ preceding _α,_ unless _β_ and _α_ were both real, and _β_ had really preceded _α._ If I say "I have _observed_ that, on one occasion, my hearing of the word 'moon' was followed by my imagining a luminous silvery disc," I commonly mean to include in my statement the assertion that I did, on that occasion, really hear the word "moon," and really did have a visual image of a luminous disc, and that my perception was really followed by my imagination. If it were proved to me that this had not really happened, I should admit that I had not really observed it. But though this condition that, if observation is to give reason for a generalisation, what is observed must be real, may thus be said to be implied in the very word "observation," it was necessary for me to mention the condition explicitly. It was necessary, because, as I shall presently show, we do and must also use the word "observation" in a sense in which the assertion "I observe A" by no means includes the assertion "A exists"--in a sense in which it _may_ be true that though I did observe A, yet A did _not_ exist.

But there is also, I think, a third necessary condition which is very apt to be overlooked. It may, perhaps, be allowed that observation gives some reason for the proposition that hens' eggs are generally laid by hens. I do not mean to say that any one man's observation can give a reason for this proposition: I do not assume either that it can or that it cannot. Nor do I mean to make any assumption as to what must be meant by the words "hens" and "eggs," if this proposition is to be true. I am quite willing to allow for the moment that if it is true at all, we must understand by "hens" and "eggs," objects very unlike that which we directly observe, when we see a hen in a yard, or an egg on the breakfast-table. I am willing to allow the possibility that, as some Idealists would say, the proposition "Hens lay eggs" is false, unless we mean by it: A certain kind of collection of spirits or monads sometimes has a certain intelligible relation to another kind of collection of spirits or monads. I am willing to allow the possibility that, as Reid and some scientists would say, the proposition "Hens lay eggs" is false, if we mean by it anything more than that: Certain configurations of invisible material particles sometimes have a certain spatio-temporal relation to another kind of configuration of invisible material particles. Or again I am willing to allow, with certain other philosophers, that we must, if it is to be true, interpret this proposition as meaning that certain kinds of sensations have to certain other kinds a relation which may be expressed by saying that the one kind of sensations "lay" the other kind. Or again, as other philosophers say, the proposition "Hens lay eggs" may possibly mean: Certain sensations of mine _would_, under certain conditions, have to certain other sensations of mine a relation which may be expressed by saying that the one set would "lay" the other set. But whatever the proposition "Hens' eggs are generally laid by hens" may _mean_, most philosophers would, I think, allow that, in some sense or other, this proposition was true. And they would also I think allow that we have _some_ reason for it; and that _part_ of this reason at all events lies in observation: they would allow that we should have no reason for it unless certain things had been observed, which have been observed. Few, I think, would say that the existence of an egg "intrinsically points" to that of a hen, in such a sense that, even if we had had no experience of any kind concerning the manner in which objects like eggs are connected with animals like hens, the mere inspection of an egg would justify the assertion: A hen has probably existed.

I assume, then, that objects having all the characteristics which hens' eggs have (whatever these may be) are generally laid by hens (whatever hens may be); and I assume that, if we have any reason for this generalisation at all, observation gives us some reason for it. But now, let us suppose that the only observations we had made were those which we should commonly describe by saying that we had seen a hen laying an egg. I do not say that any number of such observations, by themselves, would be _sufficient_ to justify our generalisation: I think it is plain that they would not. But let us suppose, for the moment, that we had observed nothing else which bore upon the connection between hens and eggs; and that, if therefore our generalisation was justified by any observations at all, it was justified by these. We are supposing, then, that the observations which we describe as "seeing hens lay eggs" give some reason for the generalisation that eggs of that kind are generally laid by hens. And if these observations give reason for this, obviously _in a sense_ they give reason for the generalisation that the existence of such an egg is generally preceded by that of a hen; and hence also, they give us reason to suppose that if such an egg exists, a hen has probably existed also--that unless a hen had existed, the egg would not have existed. But the point to which I wish to call attention is that it is _only_ in a limited sense that they do give reason for this. They only give us reason to suppose that, for each egg, there has existed a hen, which was at some time _near_ the place where the egg in question then was, and which existed at a time _near_ to that at which the egg began to exist. The only kind of hens, whose existence they do give us reason to suppose, are hens, of which each was at some time in spatial and temporal proximity (or, if Idealists prefer, in the relations which are the "intelligible counterparts" of these) to an egg. They give us no information at all about the existence of hens (if there are any) which never came within a thousand miles of an egg, or which were dead a thousand years before any egg existed. That is to say, they _do_ give us reason to suppose that, if a particular egg exists, there has probably existed a hen which was at some time _near_ that egg; but they give us no reason to suppose that, if a particular egg exists, there must have existed a hen which never came near that egg. They _do_ give us reason to suppose that, for each egg, there has probably existed a hen which at some time stood to the egg in question in that relation which we have observed to hold between an egg and a hen, when we observed the hen laying an egg. But they give us no reason to infer from the existence of an egg any other kind of hen: any hen which _never_ stood to the egg in the relation in which we have observed that some hens do stand to eggs.

What I wish to suggest is that this condition is a universal condition for sound inductions. If the observation of β preceding _α_ can ever give us any reason at all for supposing that the existence of A is generally preceded by that of B, it can at most only give us reason to suppose that the existence of an A is generally preceded by that of a B _which stands to our A in the same relation in which β_ has been observed to stand to _α._ It cannot give the least reason for supposing that the existence of an A must have been preceded by that of a B, which did _not_ stand to A in the observed relation, but in some quite different one. If we are to have any reason to infer from the existence of an A the existence of such a B, the reason must lie in some different observations. That this is so, in the case of hens' eggs and hens, is, I think, obvious: and, if the rule is _not_ universal, some reason should at least be given for supposing that it does apply in one case and not in another.

Having thus attempted to point out some conditions which seem to be necessary, though not _sufficient_, where observation is to give any reason for a generalisation, I may now proceed to my second preliminary question. What kinds of things do we observe?

In order to illustrate how much and how little I mean by "observation" or "direct perception," I will take as an instance a very common visual perception. Most of us are familiar with the experience which we should describe by saying that we had seen a red book and a blue book side by side upon a shelf. What exactly can we be said to observe or directly perceive when we have such an experience? We certainly observe one colour, which we call blue, and a different colour, which we call red; each of these we observe as having a particular size and shape; and we observe also these two coloured patches as having to one another the spatial relation which we express by saying they are side by side. All this we certainly see or directly perceive _now,_ whatever may have been the process by which we have come to perceive so much. But when we say, as in ordinary talk we should, that the objects we perceive are _books,_ we certainly mean to ascribe to them properties, which, in a sense which we all understand, are not actually seen by us, at the moment when we are merely looking at two books on a shelf two yards off. And all such properties I mean to exclude as not being then _observed_ or _directly perceived_ by us. When I speak of what we _observe,_ when we see two books on a shelf, I mean to limit the expression to that which is _actually seen._ And, thus understood, the expression does include colours, and the size and shape of colours, and spatial relations in three dimensions between these patches of colour, but it includes nothing else.

But I am also using observation in a sense in which we can be said actually to observe a movement. We commonly say that we can sometimes _see_ a red billiard ball moving towards a white one on a green table. And, here again, I do not mean to include in what is directly perceived or observed, all that we mean by saying that the two objects perceived are billiard-balls. But I do mean to include what (we should say) we _actually see._ We actually see a more or less round red patch moving towards a more or less round white patch; we _see_ the stretch of green between them diminishing in size. And this perception is not merely the same as a series of perceptions--first a perception of a red patch with a green stretch of one size between it and the white; then a perception of a red patch with a green stretch of a different size between it and the white; and so on. In order to perceive a movement we must have a different perception from any one of these or from the sum of them. We must _actually see_ the green stretch diminishing in size.

Now it is undoubtedly difficult, in some instances, to decide precisely what is perceived in this sense and what is not. But I hope I have said enough to show that I am using "perceive" and "observe" in a sense in which, on a given occasion, it is easy to decide that _some_ things certainly are perceived, and other things, as certainly, are not perceived. I am using it in a sense in which we do perceive such a complex object as a white patch moving towards a red one on a green field; but I am not using it in any sense in which we could be said to "perceive" or "observe" that what we saw moving was a billiard-ball. And in the same way I think we can distinguish roughly between what, on any given occasion, we perceive, as we say, "by any one of the other senses," and what we do not perceive by it. We can say with certainty that, on any given occasion, there are certain kinds of "content" which we are actually hearing, and others which we are _not_ actually hearing; though with regard to some again it is difficult to say whether we are actually hearing them or not. And similarly we can distinguish with certainty in some instances, between what we are on a given occasion, actually smelling or feeling, and what we are not actually smelling or feeling.