It will be seen that this kind of sameness may be presupposed in affirming sameness in other senses of the word. When I compare a present sensation with one felt some days since, and affirm that they are the same, the latter must enter into the comparison through its representative in memory. It is not itself present at the time of the comparison.
And when I say that I have seen the same tree yesterday and to-day, I mean, as I have explained, that the two percepts belong to the one series; but since my experience of yesterday cannot be itself present in my consciousness to-day, it can take its place in the series, as thought to-day, only by proxy. When I say that I have in my mind the same series on two successive days, I evidently mean that it is the same series in the sense in which any experience and its representative in memory are the same.
Other less important instances might be given of this use of the word same to express the relation between any experience and its representative. We say that we see an object in a mirror, when we mean that we see its reflected image. We speak of seeing in a picture this man or that. When we have found for anything a satisfactory substitute we say it is the same thing. Such uses of the word are not likely to deceive anyone, and I will not dwell upon them. Their meaning is too plain to be mistaken.
Sec. 7. VI. We constantly speak of two men as seeing the same thing. In this we have a sense of the word which demands careful analysis. For the sake of clearness, and to avoid ambiguity, I will confine myself here, as I have done in the foregoing sections, to an examination of what is actually experienced by the men, and will defer all consideration of existences assumed as lying beyond a possible experience in an extra-mental world, for discussion in sections to follow.
The question which interests me at present is simply this: What experience is it that leads a man to affirm that he and someone else are perceiving the same object? The Realist (in the modern sense) would say that this experience is only his evidence that he and another are perceiving the same object, meaning by object what I have referred to as believed to lie beyond his experience; while the Idealist would say that this experience exhausts the whole matter. The Realist must, however, admit, as I have brought out in a different connection, that all his evidence for the existence of the object (in his sense), and for any affirmations whatever regarding it, lying within the field of the immediately known, any words, which have been coined to express qualities of, or distinctions concerning, this object, would retain a use and significance as marking distinctions within this field even if the object were supposed non-existent. Whether any such duplicate of what is immediately perceived exists or not is a question apart. Since we admittedly draw all our distinctions from the field of the immediately known and then carry them over to such objects, and not vice versa, we may be sure that we would go on saying that two men see the same object in any case. I myself give the preference to that the existence of which is an indubitable fact, and prefer using the word object to indicate the complex in consciousness. I have, however, no desire to assume any point in dispute by juggling with a word, and will try to keep clearly in mind the meaning of the word thus assumed whenever I use it.
Now, the experience which leads me to say that I and another man see the same object is just this: I perceive a particular object, and in a certain relation to it I perceive the body of another man. From a past experience of my own body in relation to objects and from reasoning by analogy, I have come to connect such a relation of another body to the object with the thought of another consciousness of the object as connected with that body. Just as I perceive my own body to perform certain actions when I am conscious of perceiving the object, so I perceive this other body with which I have connected in thought a consciousness of the object to perform similar acts in response to similar relations towards the object. It is wholly a matter of observation in my own case that the perception of my own body in this or that relation to an object is a sine qua non to the perception of the object. And it is wholly a matter of reasoning from like to like that leads me to connect in thought sensations or percepts with any other animal body whatever. When I say, therefore, that I and another man are perceiving the same thing, there is in my mind a complex consisting of a percept or idea of the thing, a percept or idea of the man's body, and the thought of a percept connected with this body. When I say that he is thinking of us both as seeing the same thing, I call up in mind a similar complex and connect it in thought with his body. Whatever I may believe as to the existence or non-existence of things lying beyond this sphere, and supposed to cause these experiences, these are the experiences to which I ultimately refer when I speak of two men as seeing the same object, and these furnish the whole ground for the existence of the phrase.
The percept of the object which I connect in thought with the other man's body need not be wholly similar to my percept of the object. The man who has discovered that he is color-blind, does not suppose that men not similarly afflicted see just what he does in looking at a cherry tree full of ripe fruit. Nevertheless, he still speaks of himself and others as seeing the same objects. If another man's body is not exactly like mine, I am not justified by argument from similarity in reading into it an exactly similar experience. It is not the similarity of the two percepts that I am thinking of chiefly when I speak of them as percepts of the same object. I am thinking of the relation in which I suppose them to stand to each other. I think of the possible existence of the one under given circumstances as conditioning the possible existence of the other.
Sec. 8. VII. When a man in an early stage of reflection upon his experience has decided that objects immediately perceived are not the real things but merely their mental copies or representatives, he may think of these "real" things in several ways. He may believe in a world of "real" things, consisting of groups of "real" qualities, external to consciousness; he may accept such "real" things, but add to them a substratum or substance, distinct from the qualities; or he may believe that the "real" exists as mere substratum, substance, or noumenon, and that all qualities, being merely its revelation to mind, exist within the circle of consciousness alone. The first position is one not often taken. The second is that held by Locke,[2] who believed that, corresponding to our ideas of objects, there exist substances possessed of certain primary qualities, and having an underlying substance or substratum. The third represents the view of the Kantian,[3] who, to be consistent, must deny to his noumenon any qualities whatever. How he is to do this without having it lapse into utter nothingness is a problem for him to solve.
The disciple of Locke has, therefore, in discussing all the uses of the word same, to consider the sameness of:
1. Things immediately known.