Philosophical Studies · G. E. Moore
SOME JUDGMENTS OF PERCEPTION
I can, in fact, imagine that some of those who would call this thing a sensation would deny that my judgment is _about_ it at all. It would sometimes be spoken of as the sensation which mediates my perception of this inkstand in this instance. And I can imagine that some of those who would so speak of it might be inclined to say that when I judge "This is an inkstand," my judgment is about this inkstand which I perceive, and not, in any sense at all, about the sensation which mediates my perception of it. They may perhaps imagine that the sensation mediates my perception of the inkstand only in the sense that it brings the inkstand before my mind in such a way that, once it is before my mind, I can make a judgment about it, which is _not_ a judgment about the mediating sensation at all; and that such a judgment is the one I am actually expressing when I say "This is an inkstand." Such a view, if it is held, seems to me to be quite certainly false, and is what I have intended to deny.
And perhaps I can put most clearly the reason why it seems to me false, by saying that, if (which may be doubted) there is anything which is this inkstand, that thing is certainly not given to me independently of this sense-datum, in such a sense that I can possibly make a judgment about it which is _not_ a judgment about this sense-datum. I am not, of course, denying that I do perceive this inkstand, and that my judgment is, in a sense, a judgment about it. Both these things seem to me to be quite obviously true. I am only maintaining that my judgment is _also,_ in another sense, a judgment about this sense-datum which mediates my perception of the inkstand. Those who say that this sense-datum does mediate my perception of the inkstand, would, of course, admit that my perception of the inkstand is, in a sense, dependent upon the sense-datum; that it is dependent is implied in the mere statement that it is mediated by it. But it might be maintained that it is dependent on it only in the sense in which, when the idea of one object is called up in my mind, through association, by the idea of another, the idea which is called up is dependent on the idea which calls it up.
What I wish to maintain, and what seems to me to be quite certainly true, is that my perception of this inkstand is dependent on this sense-datum, in a quite different and far more intimate sense than this. It is dependent on it in the sense that, if there is anything which is this inkstand, then, in perceiving that thing, I am knowing it _only_ as _the_ thing which stands in a certain relation to this sense-datum. When the idea of one object is called up in my mind by the idea of another, I do not know the second object _only_ as _the_ thing which has a certain relation to the first: on the contrary, I can make a judgment about the second object, which is not a judgment about the first. And similarly in the case of two sense-data which are presented to me simultaneously, I do not know the one _only_ as a thing which has a certain relation to the other. But in the case of this sense-datum and this inkstand the case seems to me to be plainly quite different. If there be a thing which is this inkstand at all, it is certainly _only_ known to me as _the_ thing which stands in a certain relation to this sense-datum.
It is not given to me, in the sense in which this sense-datum is given. If there be such a thing at all, it is quite certainly only known to me by description, in the sense in which Mr. Russell uses that phrase; and the description by which it is known is that of being _the_ thing which stands to this sense-datum in a certain relation. That is to say, when I make such a judgment as "This inkstand is a good big one"; what I am really judging is: "There is a thing which stands to _this_ in a certain relation, and which is an inkstand, and that thing is a good big one"--where "_this_" stands for this presented object. I am referring to or identifying the thing which is this inkstand, if there be such a thing at all, only as the thing which stands to this sense-datum in a certain relation; and hence my judgment, though in one sense it may be said to be a judgment about the inkstand, is quite certainly also, in another sense, a judgment about this sense-datum. This seems to me so clear, that I wonder how anyone can deny it; and perhaps nobody would.
But I cannot help thinking that it is not clear to everybody; partly because, so far as I can make out, nobody before Mr. Russell had pointed out the extreme difference there is between a judgment about a thing known only by description to the individual who makes the judgment, and a judgment about a thing not known to him only in this way; and partly because so many people seem still utterly to have failed to understand what the distinction is which he expresses in this way. I will try to make the point clear, in a slightly different way. Suppose I am seeing two coins, lying side by side, and am not perceiving them in any other way except by sight. It will be plain to everybody, I think, that, when I identify the one as "This one" and the other as "That one," I identify them only by reference to the two visual presented objects, which correspond respectively to the one and to the other.
But what may not, I think, be realised, is that the sense in which I identify them by reference to the corresponding sense-data, is one which involves that every judgment which I make about the one is a judgment about the sense-datum which corresponds to it, and every judgment I make about the other, a judgment about the sense-datum which corresponds to _it_: I simply cannot make a judgment about either, which is not a judgment about the corresponding sense-datum. But if the two coins were given to me, in the sense in which the two sense-data are, this would certainly not be the case. I can identify and distinguish the two sense-data _directly,_ this as this one, and that as that one: I do not need to identify either as _the_ thing which has this relation to this other thing. But I certainly cannot thus directly identify the two coins. I have not four things presented to me (1) _this_ sense-datum, (2) _that_ sense-datum, (3) _this_ coin, and (4) _that_ coin, but two only_--this_ sense-datum and _that_ sense-datum. When, therefore, I judge "_This_ is a coin," my judgment is certainly a judgment about the one sense-datum, and when I judge "And _that_ is also a coin," it is certainly a judgment about the other. Only, in spite of what my language might seem to imply, I am certainly not judging either of the one sense-datum that it is a whole coin, nor yet of the other that it is one.
This, then, seems to me fundamentally certain about judgments of this kind. Whenever we make such a judgment we can easily pick out an object (whether we call it a sensation or a sense-datum, or not), which is, in an easily intelligible sense, _the_ object which is the real or ultimate subject of our judgment; and yet, in many cases at all events, what we are judging with regard to this object is certainly not that it is an object of the kind, for which the term which appears to express the predicate of our judgment is a name. But if this be so, what is it that I am judging, in all such cases, about the presented object, which is the real or ultimate subject of my judgment? It is at this point that we come to questions which seem to me to be really uncertain and difficult to answer.
To begin with, there is one answer which is naturally suggested by the reason I have given for saying that, in this case, it is quite obvious that I am not judging, with regard to this presented object, that _it_ is an inkstand, whereas it is not in the same way, quite obvious that, in making such a judgment as "This is a soap-bubble" or "This is a drop of water," I may not be judging, of the object about which my judgment is, that that very object really is a soap-bubble or a drop of water. The reason I gave is that it is quite obvious that I do not take this presented object to be a _whole_ inkstand: that, at most, I only take it to be part of the surface of an inkstand. And this reason naturally suggests that the true answer to our question may be that what I am judging of the presented object is just that it is a part of the surface of an inkstand. This answer seems to me to be obviously on quite a different level from the suggestion that I am judging it really to be an inkstand. It is not childishly obvious that I am not judging it to be part of the surface of an inkstand, as it is that I am not judging it to be an inkstand--a whole one.
On this view, when I say such things as "That is an inkstand," "That is a door," "This is a coin," these expressions would really only be a loose way of saying "That is part of the surface of an inkstand," "That is part of the surface of a door," "This is part of the surface of a coin." And there would, I think, plainly be nothing surprising in the fact that we should use language thus loosely. What, at first sight, appears to be a paradox, namely that, whereas I appear to be asserting of a given thing that it is of a certain kind, I am not really asserting of the thing in question that it is of that kind at all, would be susceptible of an easy explanation. And moreover, if this view were true, it would offer an excellent illustration of the difference between a thing known only by description and a thing not so known, and would show how entirely free from mystery that distinction is. On this view, when I judge "That inkstand is a good big one" I shall in effect be judging: "There is one and only one inkstand of which _this_ is part of the surface, and the inkstand of which this is true is a good big one." It would be quite clear that the part of the surface of the inkstand was given to me in a sense in which the whole was not, just as it is in fact clear that I do now _"see"_ this part of the surface of this inkstand, in a sense in which I do _not_ "see" the whole; and that my judgment, while it is, in fact, _about_ both the whole inkstand, and also _about_ one particular part of its surface, is _about_ them in two entirely different senses.
This view is one, which it is at first sight, I think, very natural to suppose to be true. But before giving the reasons, why, nevertheless, it seems to me extremely doubtful, I think it is desirable to try to explain more precisely what I mean by it. The word "part" is one which is often used extremely vaguely in philosophy; and I can imagine that some people would be willing to assent to the proposition that this sense-datum really is, in some sense or other, a "part" of this inkstand, and that what I am judging with regard to it, when I judge "This is an inkstand," is, in effect, "There is an inkstand, of which _this_ is a part," who would be far from allowing that this can possibly be what I am judging, when once they understand what the sense is in which I am here using the word "part." What this sense is, I am quite unable to define; but I hope I may be able to make my meaning sufficiently clear, by giving instances of things which are undoubtedly "parts" of other things in the sense in question.
There is, it seems to me, a sense of the word "part," in which we all constantly use the word with perfect precision, and, which, therefore, we all understand very well, however little we may be able to define it. It is the sense in which the trunk of any tree is undoubtedly a part of that tree; in which this finger of mine is undoubtedly a part of my hand, and my hand a part of my body. This is a sense in which every part of a material thing or physical object is itself a material thing or physical object; and it is, so far as I can see, the only proper sense in which a material thing can be said to have parts. The view which I wish to discuss is the view that I am judging this presented object to be a part of an inkstand, in this sense. And the nature of the view can perhaps be brought out more clearly, by mentioning one important corollary which would follow from it. I am, of course, at this moment, seeing many parts of the surface of this inkstand. But all these parts, except one, are, in fact, themselves parts of that one.
That one is the one of which we should naturally speak as "_the_ part of the surface that I am now seeing" or as "_this_ part of the surface of this inkstand." There is only one part of the surface of this inkstand, which does thus contain, as parts, all the other parts that I am now seeing. And, if it were true that I am judging this presented object to be a part of the surface of an inkstand at all, in the sense I mean, it would follow that this presented object must, if my judgment "This is an inkstand" be true (as it certainly is), be identical with this part, which contains all the other parts which I am seeing; since there is plainly no other part with which it could possibly be identified. That is to say, if I am really judging of this presented object that it is part of the surface of an inkstand, in the sense I mean, it must be the case that everything which is true of what I should call "this part of the surface of this inkstand" is, in fact, true of this presented object.
This view, therefore, that what we are judging of the ultimate subject of our judgment, when we judge "This is a so-and-so," is, in general, merely that the subject in question is a _part_ of a thing of the kind in question, can, I think, be most clearly discussed, by asking whether, in this case, this presented object can really be identical with this part of the surface of this inkstand. If it can't, then most certainly I am not judging of it that it is a part of the surface of an inkstand at all. For my judgment, whatever it is, is true. And yet, if this presented object is not identical with this part of the surface of this inkstand, it certainly is not a part of an inkstand at all; since there is no other part, either of this inkstand or of any other, with which it could possibly be supposed to be identical. Can we, then, hold that this sense-datum really is identical with this part of the surface of this inkstand? That everything which is true of the one is true of the other?
An enormous number of very familiar arguments have been used by various philosophers, which, if they were sound, would show that we can not. Some of these arguments seem to me to be quite clearly not sound--all, for instance, which rest either on the assumption that this sense-datum can only exist so long as it is perceived, or on the assumption that it can only exist so long as it is perceived _by me._ Of others I suspect that they may have some force, though I am quite unable to see that they have any. Such, for instance, are all those which assume either that this sense-datum is a sensation or feeling of mine, in a sense which includes the assertion that it is dependent on my mind in the very same sense in which my perception of it obviously is so; or that it is causally dependent on my body in the sense in which my perception of it admittedly is so. But others do seem to me to have great force. I will, however, confine myself to trying to state one, which seems to me to have as much as any. It will be found that this one involves an assumption, which does seem to me to have great force, but which yet seems to me to be doubtful. So far as I know, all good arguments against the view that this sense-datum really is identical with this part of the surface of the inkstand, do involve this same assumption, and have no more force than it has. But in this, of course, I may be wrong. Perhaps some one will be able to point out an argument, which is obviously quite independent of it, and which yet has force.
The argument I mean involves considerations which are exceedingly familiar, so familiar that I am afraid every one may be sick of hearing them alluded to. But, in spite of this fact, it seems to me not quite easy to put it quite precisely, in a way which will distinguish it clearly from other arguments involving the same familiar considerations, but which do not seem to me to be equally cogent. I want, therefore, to try to put it with a degree of precision, which will prevent irrelevant objections from being made to it--objections which would, I think, be relevant against some of these other arguments, but are not, I think, relevant against it. The fact is that we all, exceedingly commonly, when, at each of two times, separated by a longer or shorter interval, we see a part of the surface of a material thing, in the sense in which I am now seeing this part of the surface of this inkstand, or when at one time we see such a surface and at another perceive one by touch, make, on the second occasion, the judgment "_This_ part of a surface is the _same_ part of the surface of the same thing, as that which I was seeing (or perceiving by touch) just now." How commonly we all do this can scarcely be exaggerated. I look at this inkstand, and then I look again, and on the second occasion I judge "This part of the surface of this inkstand is the same as, or at least contains a part which is the same as a part of, the part of its surface which I was seeing just now." Or I look at this finger and then I touch it, and I judge, on the second occasion, "This part of the surface of this finger is the same as one of those I was seeing just now." We all thus constantly identify a part of a surface of a material thing which we are perceiving at one time with a part which we _were_ perceiving at another.
Now, when we do this--when we judge "This is the _same_ part of the same thing as I was seeing or touching just now," we, of course, do not mean to exclude the possibility that the part in question may have changed during the interval; that it is really different, on the second occasion, either in shape or size or quality, or in all three, from what it was on the first. That is to say, the sense of sameness which we are here concerned with is one which clearly does not exclude change. We may even be prepared to assert, on general grounds, in all such cases, that the surface in question certainly must have changed. But nevertheless there is a great difference in one respect, between two kinds of such cases, both of which occur exceedingly commonly. If I watch somebody blowing air into a child's balloon, it constantly happens, at certain stages in the process, that I judge with regard to the part of the surface which I am seeing at that stage, not only that it _is_ larger than it was at an earlier stage, but that it is _perceptibly_ larger.
Or, if I pull the face of an india-rubber doll, I may judge at a certain stage in the process that the patch of red colour on its cheek not only is different in shape from what it was at the beginning, but is _perceptibly_ so; it may, for instance, be a perceptibly flatter ellipse than it was to start with. Or, if I watch a person blushing, I may judge at a certain stage that a certain part of the surface of his face not only is different in colour from what it was, when I saw it before he began to blush, but is _perceptibly_ so--perceptibly redder. In enormous numbers of cases we do thus judge of a surface seen at a given time that it is thus _perceptibly_ different in size, or in shape, or in colour, from what it was when we saw it before.
But cases are at least equally numerous in which, though we might, on general grounds be prepared to assert that it _must_ have changed in some respect, we should not be prepared to assert that it had, in any respect whatever, changed _perceptibly._ Of this part of this surface of this inkstand, for instance, I am certainly not prepared to assert that it is now perceptibly different in any respect from what it was when I saw it just now. And similar cases are so numerous that I need not give further instances. We can, therefore, divide cases, in which we judge, of a part of a surface which we are seeing, "This is the same part of the surface of the same material thing as the one I saw just now," into cases where we should also judge "But it is perceptibly different from what it was then," and cases in which, even though we might assert "It _must_ be different," we are certainly not prepared to assert that it is _perceptibly_ so.
But now let us consider the cases in which we are not prepared to assert that the surface in question has changed perceptibly. The strange fact, from which the argument I mean is drawn, is that, in a very large number of such cases, it seems as if it were unmistakably true that the presented object, about which we are making our judgment when we talk of "This surface" at the later time, _is_ perceptibly different, from that about which we are making it when we talk of the surface I saw just now. If, at the later time, I am at a sufficiently greater distance from the surface, the presented object which corresponds to it at the time seems to be perceptibly smaller, than the one which corresponded to it before. If I am looking at it from a sufficiently oblique angle, the later presented object often seems to be perceptibly different in shape--a perceptibly flatter ellipse, for instance. If I am looking at it, with blue spectacles on, when formerly I had none, the later presented object seems to be perceptibly different in colour from the earlier one.
Ideas discussed in this chapter
Text from Project Gutenberg, public domain in the United States.