Part 16

However that may be, one relation, in which sensibles of all sorts do sometimes stand to our minds, is the relation constituted by the fact that we directly apprehend them: or, to speak more accurately, by the fact that events which consist in their being directly apprehended are _in_ our minds, in the sense in which to say that an event is _in_ our minds means merely that it is a mental act of _ours_--that it has to our other mental acts that relation (whatever it may be) which we mean by saying that they are all mental acts _of the same individual._ And it is clear that to say of a sensible that it is directly apprehended by me, is to say of it something quite different from what I say of a mental act of mine, when I say that this _mental act is in my mind_: for nothing is more certain than that an act of direct apprehension or belief may be in my mind, without being itself directly apprehended by me. If, therefore, by saying that a sensible is _in our minds_ or is _ours,_ we mean merely that it is directly apprehended by us, we must recognise that we are here using the phrases "in our minds" or "ours" in quite a different sense from that in which we use them when we talk of our mental acts being "in our minds" or "ours." And why I say this is because I think that these two relations are very apt to be confused. When, for instance, we say of a given entity that it is "experienced," or when the Germans say that it is "erlebt," it is sometimes meant, I think, merely that it is directly apprehended, but sometimes that it is in my mind, in the sense in which, when I entertain a belief, this act of belief is in my mind.

But (2) it seems to me to be commonly held that sensibles are often in our minds in some sense quite other than that of being directly apprehended by us or that of being thought of by us. This seems to me to be often what is meant when people say that they are "immediately experienced" or are "subjective modifications"; though, of course, both expressions are so ambiguous, that when people say that a given entity is immediately experienced or is a subjective modification, they _may_ mean merely that it is directly apprehended. And since I think this view is held, I want to explain that I see no reason whatever for thinking that sensibles ever are experienced by us in any other sense than that of being directly apprehended by us. Two kinds of argument, I think, are sometimes used to show that they are.

(_a_) It is a familiar fact that, when, for instance, we are in a room with a ticking clock, we may seem suddenly to become aware of the ticks, whereas, so far as we can tell, we had previously not heard them at all. And it may be urged that in these cases, since the same kind of stimulus was acting on our ears all the time, we must have _experienced_ the same kind of sensible sounds, although we did not directly apprehend them.

But I think most psychologists are now agreed that this argument is quite worthless. There seem to me to be two possible alternatives to the conclusion drawn. It may, I think, possibly be the case that we did directly apprehend the ticks all the time, but that we cannot afterwards remember that we did, because the degree of attention (if any) with which we heard them was so small, that in ordinary life we should say that we did not attend to them at all. But, what, I think, is much more likely is that, though the same stimulus was acting on our ears, it failed to produce any mental effect whatever, because our attention was otherwise engaged.

(_b_) It is said that sometimes when we suddenly become aware, say, of the eighth stroke of a striking clock, we can _remember_ earlier strokes, although we seem to ourselves _not_ to have directly apprehended them. I cannot say that I have ever noticed this experience in myself, but I have no doubt that it is possible. And people seem inclined to argue that, since we can remember the earlier strokes, we must have experienced them, though we did not directly apprehend them.

But here again, the argument does not seem to me at all conclusive. I should say, again, that it is possible that we did directly apprehend them, but only with a very slight degree of attention (if any). And, as an alternative, I should urge that there is no reason why we should not be able to remember a thing, which we never experienced at all.

I do not know what other arguments can be used to show that we sometimes _experience_ sensibles in a sense quite other than that of directly apprehending them. But I do not know how to show that we do not; and since people whose judgment I respect, seem to hold that we do, I think it is worth while to say something as to what this sense of "experience" can be, in case it does occur.

I have said that sometimes when people say that a given entity is "experienced" they seem to mean that it belongs to some individual, in the sense in which my acts of belief belong to me. To say that sensibles were experienced by me in this sense would, therefore, be to say that they sometimes have to my acts of belief and acts of direct apprehension the same relation which these have to one another--the relation which constitutes them _mine._ But that sensibles ever have this kind of relation to my mental acts, is a thing which I cannot believe. Those who hold that they are ever experienced at all, in some sense other than that of being directly apprehended, always hold, I think, that, whenever they are directly apprehended by us, they also, at the same time, have to us this other relation as well. And it seems to me pretty clear that when I do directly apprehend a sensible, it does _not_ have to me the same relation which my direct apprehension of it has.

If, therefore, sensibles are ever experienced by us at all, in any sense other than that of being directly apprehended by us, we must, I think, hold that they are so in an entirely new sense, quite different both from that in which to be experienced means to be directly apprehended, and from that in which to be experienced means to occur in some individual's mind. And I can only say that I see no reason to think that they ever are experienced in any such sense. If they are, the fact that they are so is presumably open to the inspection of us all; but I cannot distinguish any such fact as occurring in myself, as I can distinguish the fact that they are directly apprehended. On the other hand, I see no way of showing that they are _not_ experienced in some such sense; and perhaps somebody will be able to point it out to me. I do not wish to assume, therefore, that there _is_ no such sense; and hence, though I am inclined to think that the _only_ sense in which they are experienced is that of being directly apprehended, I shall, in what follows, use the phrase "experienced" to mean _either_ directly apprehended _or_ having to something this supposed different relation, if such a relation there be.

(3) We may now, therefore, raise the question: Do sensibles ever exist at times when they are not being experienced at all?

To this question it is usual to give a negative answer, and two different _a priori_ reasons may be urged in favour of that answer.

The first is what should be meant by Berkeley's dictum that the _esse_ of sensibles is _percipi._ This should mean, whatever else it may mean, at least this: that to suppose a sensible to exist and yet _not_ to be experienced in self-contradictory. And this at least seems to me to be clearly false. Anything which was a patch of colour would be a sensible; and to suppose that there are patches of colour which are not being experienced is clearly not self-contradictory, however false it may be.

It may, however, be urged (and this is the second argument) that, though to suppose a thing to be a sensible and _yet_ not experienced is not self-contradictory, yet we can clearly see that nothing can have the one property without having the other. And I do not see my way to deny that we may be able to know, _a priori_ that such a connection holds between two such properties. In the present case, however, I cannot see that it does hold, and therefore, so far as _a priori_ reasons go, I conclude that there is no reason why sensibles should not exist at times when they are not experienced.

It may, however, be asked: Is there any reason to suppose that they ever do? And the reason, which weighs with me most, is one which applies, I think, to a certain class of sensibles _only_; a class which I will try to define by saying that it consists of those which _would_ (under certain conditions which actually exist) be experienced in a _sensation proper, if only_ a living body, having a certain constitution, existed under those conditions in a position in which no such body does actually exist. I think it is very probable that this definition does not define at all accurately the kind of sensibles I mean; but I think that what the definition aims at will become clearer when I proceed to give my reasons for supposing that sensibles, of a kind to be defined in _some_ such way, do exist unexperienced. The reason is simply that, in Hume's phrase, I have "a strong propensity to believe" that, _e.g.,_ the visual sensibles which I directly apprehend in looking at this paper, still exist unchanged when I merely alter the position of my body by turning away my head or closing my eyes, _provided_ that the physical conditions outside my body remain unchanged. In such a case it is certainly true in some sense that I _should_ see sensibles like what I saw the moment before, _if only_ my head were still in the position it was at that moment or my eyes unclosed. But if, in such a case, there is reason to think that sensibles which I should see, if the position of my body were altered, exist in spite of the fact that I do not experience them, there is, I think, an equal reason to suppose it in other cases. We must, for instance, suppose that the sensibles which I should see now, if I were at the other end of the room, or if I were looking under the table, exist at this moment, though they are not being experienced. And similarly we must suppose that the sensibles which _you_ would see, if you were in the position in which I am now, exist at this moment, in spite of the fact that they may be more or less different from those which I see, owing to the different constitution of our bodies. All this implies of course, that a vast number of sensibles exist at any moment, which are not being experienced at all. But still it implies this only with regard to sensibles of a strictly limited class, namely sensibles which would be experienced _in a sensation proper,_ if a body, having a certain constitution, were in a position in which it is not, under the given physical conditions. It does not, for instance, imply that any _images,_ of which it may be true that I _should_ have them, under present physical conditions, if the position of my body were altered, exist now; nor does it imply that sensibles which _would_ be experienced by me now in a sensation proper, if the physical conditions external to my body were different from what they are, exist now.

I feel, of course, that I have only succeeded in defining miserably vaguely the kind of sensibles I mean; and I do not know whether the fact that I have a strong propensity to believe that sensibles of a kind to be defined in some such way, do exist unexperienced, is any good reason for supposing that they actually do. The belief may, of course, be a mere prejudice. But I do not know of any certain test by which prejudices can be distinguished from reasonable beliefs. And I cannot help thinking that there may be a class of sensibles, capable of definition in _some_ such way, which there really is reason to think exist unexperienced.

But, if I am not mistaken, there is an empirical argument which, though, even if it were sound, it would have no tendency whatever to show that _no_ sensibles exist unexperienced, would, if it were sound, show that this very class of sensibles, to which alone my argument for unexperienced existence applies, certainly do not so exist. This, it seems to me, is the most weighty argument which can be used upon the subject; and I want, therefore, to give my reasons for thinking that it is fallacious.

The argument is one which asserts that there is abundant empirical evidence in favour of the view that the existence of the sensibles which we experience at any time, always depends upon the condition of our nervous system: so that, even where it also depends upon external physical conditions, we can safely say that sensibles, which we should have experienced, if only our nervous system had been in a different condition, certainly do not exist, when it is not in that condition. And the fallacy of this argument seems to me to lie in the fact that it does not distinguish between the existence of the sensibles _which_ we experience and _the fact that we experience them._ What there _is_ evidence for is that _our experience_ of sensibles always depends upon the condition of our nervous system; that, according as the condition of the nervous system changes, different sensibles are _experienced_, even where other conditions are the same. But obviously the fact that our experience of a given sensible depends upon the condition of our nervous system does not directly show that the existence of _the sensible experienced_ always also so depends. The fact that I am now experiencing this black mark is certainly a different fact from the fact that this black mark now exists. And hence the evidence which does tend to show that the former fact would not have existed if my nervous system had been in a different condition, has no tendency to show that the latter would not have done so either. I am sure that this distinction ought to be made; and hence, though I think there may be other reasons for thinking that the very existence of the sensibles, which we experience, and not merely the fact that we experience them _does_ always depend upon the condition of our nervous systems, it seems to me certain that this particular argument constitutes no such reason.

And I think that those who suppose that it does are apt to be influenced by an assumption, for which also, so far as I can see, there is no reason. I have admitted that the only reason I can see for supposing that sensibles which we experience ever exist unexperienced, seems to lead to the conclusion that the sensibles which would be seen by a colour-blind man, if he occupied exactly the position which I, who am not colour-blind, now occupy, exist now, just as much as those which I now see. And it may be thought that this implies that the sensibles, which he would see, and which would certainly be very different from those which I see, are nevertheless at this moment in exactly the same place as those which I see. Now, for my part, I am not prepared to admit that it is impossible they should be in the same place. But the assumption against which I wish to protest, is the assumption that, if they exist at all, they _must_ be in the same place. I can see no reason whatever for this assumption. And hence any difficulties there may be in the way of supposing that they could be in the same place at the same time as the sensibles which I see, do not at all apply to my hypothesis, which is only that they exist _now, not_ that they exist _in the same place_ in which mine do.

On this question, therefore, as to whether sensibles ever exist at times when they are not experienced, I have only to say (1) that I think there is certainly no good reason whatever for asserting that _no_ sensibles do; and (2) that I think perhaps a certain amount of weight ought to be attached to our instinctive belief that certain kinds of sensibles do; and that here again any special arguments which may be brought forward to show that, whether some sensibles exist unexperienced or not, _this_ kind certainly do not, are, so far as I can see, wholly inconclusive.

(II)

I now pass to the question how sensibles are related to physical objects. And here I want to say, to begin with, that I feel extremely puzzled about the whole subject. I find it extremely difficult to distinguish clearly from one another the different considerations which ought to be distinguished; and all I can do is to raise, more or less vaguely, certain questions as to how certain _particular_ sensibles are related to certain _particular_ physical objects, and to give the reasons which seem to me to have most weight for answering these questions in one way rather than another. I feel that all that I can say is very tentative.

To begin with, I do not know how "physical object" is to be defined, and I shall not try to define it. I shall, instead, consider certain propositions, which everybody will admit to be propositions _about_ physical objects, and which I shall assume that I know to be true. And the question I shall raise is as to how these propositions are to be interpreted_--in what sense_ they are true; in considering which, we shall at the same time consider how they are related to certain sensibles.

I am looking at two coins, one of which is a half-crown, the other a florin. Both are lying on the ground; and they are situated obliquely to my line of sight, so that the visual sensibles which I directly apprehend in looking at them are visibly elliptical, and not even approximately circular. Moreover, the half-crown is so much farther from me than the florin that _its_ visual sensible is visibly smaller than that of the florin.

In these circumstances I am going to assume that I know the following propositions to be true; and no one, I think, will deny that we can know such propositions to be true, though, as we shall see, extremely different views may be taken as to what they mean. I know (_a_) that, in the ordinary sense of the word "see" I am _really seeing two coins;_ an assertion which includes, if it is not identical with, the assertion that the visual experiences, which consist in my direct apprehension of those two elliptical patches of colour, _are_ sensations proper, and are not either hallucinations nor mere experiences of "images"; (_b_) that the upper sides of the coins are _really_ approximately circular, and not merely elliptical like the visual sensibles; (_c_) that the coins _have_ another side, and an inside, though I don't see it; (_d_) that the upper side of the half-crown is really _larger_ than that of the florin, though its visual sensible is _smaller_ than the visual sensible of the upper side of the florin: (_e_) that both coins continue to exist, even when I turn away my head or shut my eyes; but in saying this, I do not, of course, mean to say that there is absolutely _no_ change in them; I daresay there must be _some_ change, and I do not know how to define exactly what I do mean. But we can, I think, say at least this: viz., that propositions (_h_), (_c_), and (_d_) will still be true, although proposition (_a_) has ceased to be true.

Now all these propositions are, I think, typical propositions of the sort which we call propositions about physical objects; and the two coins themselves _are_ physical objects, if anything is. My question is: _In what sense_ are these propositions true?

And in considering this question, there are, I think, two principles which we can lay down as certain to begin with; though they do not carry us very far.

The one is (_a_) that the upper side of the coin, which I am said to _see,_ is not simply identical with the visual sensible which I _directly apprehend_ in seeing it. That this is so might be thought to follow absolutely from each of the two facts which I have called (_b_) and (_d_); but I am not quite sure that it does follow from either of these or from both together: for it seems to me just possible that the two sensibles in question, though _not_ circular _in my private space,_ may yet be circular in _physical_ space; and similarly that though the sensible of the half-crown is smaller than that of the florin _in my private space,_ it may be larger _in physical space._ But what I think it does follow from is the fact that another person may be seeing the upper side of the coin in exactly the same sense in which I am seeing it, and yet his sensible be certainly different from mine. From this it follows absolutely that the upper side of the coin cannot be identical with _both_ sensibles, since they are _not_ identical with one another. And though it does not follow absolutely that it may not be identical with _one_ of the two, yet it does follow that we _can_ get a case in which it is not identical with _mine_ and I need only assume that the case I am taking is such a case.

From this it follows that we must distinguish that sense of the word "see" in which we can be said to "see" a physical object, from that sense of the word in which "see" means merely to directly apprehend a visual sensible. In a proposition of the form "I see A," where A is a name or description of some physical object, though, if this proposition is to be true, there must be some visual sensible, B, which I am directly apprehending, yet the proposition "I see A" is certainly not always, and probably never, identical in meaning with the proposition "I directly apprehend B." In asserting "I see A" we are asserting not only that we directly apprehend some sensible but also something else about this sensible--it may be only some proposition of the form, "and this sensible has certain other properties," or it may be some proposition of the form "and _I know_ this sensible to have certain other properties." Indeed we have not only to distinguish that sense of the word "perceive" in which it is equivalent to "directly apprehend," from _one_ sense in which we can be said to perceive a physical object; we have also to distinguish at least two different senses in which we can be said to perceive physical objects, different both from one another and from "directly apprehend." For it is obvious that though I should be said to be now seeing _the half-crown_, there is a narrower, and more proper, sense, in which I can only be said to _see_ one side of it_--not_ its lower side or its inside, and not therefore the whole half-crown.

The other principle, which we can lay down to start with is (_β_) that my knowledge of all the five propositions (_a_) to (_e_), is based, in the last resort, on experiences of mine consisting in the direct apprehension of sensibles and in the perception of relations between directly apprehended sensibles. It is _based_ on these, in at least this sense, that I should never have known any of these propositions if I had never directly apprehended any sensibles nor perceived any relations between them.

What, in view of these two principles, can be the sense in which my five propositions are true?