The appeal to the testimony of the eyes needs examination. To what eyes does one appeal? The immediately known or idea-eyes, or the "external" organs whose existence is the matter of dispute? Surely not to the last, for it is only as a result of the argument that we may assume these at all. And what hand is it so certain that I move in writing? The complex of ideas immediately known, or the something beyond, whose existence is to be established? If it be the latter, all discussion is unnecessary. If, on the other hand, the eyes and the hand concerned are ideas, it is not clear how the appeal to them can be of any service. Does a sense give anything but sensations? And if the very sense organ as immediately known be a group of sensations, how can the testimony of a sense land one in a world beyond that of sensations? And the argument that God has given me assurance of the existence of things without me, since by applying them to myself I can produce in myself pain and pleasure, presupposes that I can apply such things to myself and know that I am doing so. If this be the fact, it is trifling to discuss whether things I move to and fro exist. If, however, it is still to be proved that there are such things, and that they are moved to and fro, the argument is wholly baseless. Locke here makes appeal to the common experience that certain objects applied to the body cause pleasure, and certain others pain; a fact which no reasonable man would think of denying or questioning, as it is matter of daily observation. But in such experiences, all that is immediately evident is that an object immediately perceived (Locke's idea) is applied to another object immediately perceived (idea) with a resulting (idea) pain. Whether or not certain duplicates of the things immediately known are brought into a peculiar conjunction at the same time is wholly problematic, and would seem to remain so until some evidence be advanced of the existence of such duplicates. This argument on the part of our author shows most clearly that for the time being he lost the distinction between ideas and "real" things. They are the same in sense seventh; he assumed them to be the same in sense first. He falls into this error again and again.
The general appeal to the testimony of the senses is followed by four special arguments. According to the first of these, it is plain that perceptions are produced in us by exterior causes affecting our senses, "because those that want the organs of any sense never can have the ideas belonging to that sense produced in their minds." This is supposed to prove that they come in by the organs of that sense, and in no other way. But here again one may ask, What is meant by the organs of any sense? If the "real" external organ be meant, one may object that its existence has not yet been proved. If the organ immediately known be meant, one has only called attention to the fact that certain ideas are a sine qua non to the existence of certain other ideas. How this tends to prove the existence of something distinct from ideas is not apparent. Locke's impulse in this argument finds its source in our common experience that bodily organs immediately perceived are proved by observation to be prerequisites to the experiencing of ideas. We see a given object in a certain relation to a normal human body, and we infer an idea of the object connected with that body. We say the man has an idea of the object, and can only infer the object itself. We connect the idea with some particular part of his body, and regard this as the medium through which he gains the idea. All this is reasonable enough. It is well to remember, however, that in all this the "real" object is not observed to play any part. The object which I certainly see in relation to the body which I certainly see is what Locke would call an idea. The man's body is an idea. The idea which I assume the man to have is to me, if I remain within the sphere of the observable, an idea of the (idea) object I see. If I am to get any "real" object at all it is not by reference to observation or experience. If I am to get it by inference, some ground must be furnished for inference. Again Locke has confounded the observable with the "real." It is only on this ground that the appeal to the sense organ has any force.
The second and the third arguments busy themselves to show that there are unmistakable differences between ideas which have their origin in the "brisk acting" of objects without and ideas of memory or imagination. The two classes are shown to be distinct, and it is very properly held that ideas of different kinds should not be confounded. But the statement, that ideas may be divided into two classes, is a very different one from the statement that the two classes differ in that one has external correlates and the other has not. One may admit all the distinctions which Locke makes in the field of ideas; and, it being once proved that such distinctions imply a world of "real" things in relation to certain ideas, may grant very readily that these ideas have corresponding to them "real" things, or that ideas caused by "real" things differ by such and such marks from other ideas. But, until it be proved that the marks in question do give a right to infer "real" things, it should not be assumed that any given class of ideas is caused by "real" things. What is to be discovered is assumed. And it is assumed here, as above, because Locke could not keep distinct the two classes of things. He is capable of saying, "But if I turn my eyes at noon towards the sun, I cannot avoid the ideas which the light, or sun, then produces in me," when the whole dispute is over the question whether there be a "real" sun toward which "real" eyes may be turned. How does he know that he is turning his eyes toward the sun? Does he not see it up there? Is he not "actually looking upon it?" His error is too plain to overlook. But if one could doubt his confusion of the two suns, the apparent and the "real," his illustration from the diagrams used in mathematical demonstration would lay the doubt once for all. "Real" lines exist, "for it would be very strange that a man should allow it for an undeniable truth, that two angles of a figure, which he measures by lines and angles of a diagram, should be bigger one than the other; and yet doubt of the existence of those lines and angles, which by looking on he makes use of to measure that by." The English is not as bad as the reasoning.
The fourth argument is derived from the fact that one sense supports the testimony of another. "He that sees a fire may, if he doubt whether it be anything more than a bare fancy, feel it too." A bare fancy, Locke is sure, would not cause such acute pain. This comes back to the second and third arguments and may be criticized in the same way. If one could refer to a single observation of the fact that "real" things do not accompany ideas of the fancy and that they do accompany ideas of a different class, the argument would be unobjectionable. Wanting this observation, or something to take its place, nothing is proved. And as to the senses helping each other to "real" things, if each sense only gives the idea appropriate to it, it is not easy to see how two together prove more than one alone. In this section, too, Locke is assuming that "real" things belong to the world of things immediately perceived. He can, he says, make what characters he pleases on the paper before him, but once having made them, cannot choose but see them as they are. "Whence it is manifest, that they are not barely the sport and play of my own imagination, when I find that the characters that were made at the pleasure of my own thought, do not obey them; nor yet cease to be, whenever I shall fancy it; but continue to affect the senses constantly and regularly, according to the figures I made them." That is, the ideas which he concludes not to be ideas of imagination are the things "which continue to affect the senses," or the "real" things. There is little wonder that this author believed in "real" things.
Sec. 32. Excellent work has been done by Berkeley in distinguishing samenesses. His treatment of sameness in sense third I have already quoted. His discussion of the infinite divisibility of finite lines,[57] a matter of which I shall speak more fully later, again brings out sense third. Almost his whole philosophy consists in the endeavor to keep clearly in mind the significance of sense seventh, and to develop what it implies. On the other hand, he has fallen into the error of confusing sense first and sense sixth, and of using this confusion to silence an objection to his doctrine.
He takes up in the "Principles," for the purpose of refuting it, the objection that his doctrine makes things every moment annihilated and created anew.[58] This, he argues, "will not be found reasonably charged on the principles we have premised, so as in truth to make any objection at all against our notions. For, though we hold indeed the objects of sense to be nothing else but ideas which cannot exist unperceived; yet we may not hence conclude they have no existence except only while they are perceived by us, since there may be some other spirit that perceives them though we do not. Wherever bodies are said to have no existence without the mind, I would not be understood to mean this or that particular mind, but all minds whatsoever. It does not therefore follow from the foregoing principles that bodies are annihilated and created every moment, or exist not at all during the intervals between our perception of them."
To the reader of Mill it is clear enough that Berkeley is not content to assume potential existence as an integral part of the life history of an object. It seems odd that he should not do so, as he has himself pointed out the double sense of the word exist.[59] However, he demands actual existence. Any lapse in the actual existence of the immediate object seems to him a destruction of the object. He has the common feeling that it is contrary to nature that things should be destroyed and created from moment to moment. They must exist continuously. They evidently do not actually exist continuously in the one mind. So he assumes that, during the periods of their absence from one mind, they must exist in another: otherwise they could not be said to exist at all.
Of course, all this assumes that the objects in one mind are identically (sense first) the objects in another. If they be recognized as two distinct things, belonging to different worlds—worlds so different that what is in one can enter the other only through its representative—the whole argument is seen to be fallacious. One can no more make a consistent whole of elements taken from two different consciousnesses, than one can piece out a grief with a smell. The attempt is the result of overlooking the duality implied in sameness in sense sixth.
Sec. 33. There is a clear and forcible passage in John Stuart Mill's "System of Logic," in which he distinguishes certain samenesses from certain others. It is to be regretted that he dismissed the subject with so slight an examination, for it could not but have gained by a careful analysis at the hands of this keen man. I quote more particularly to bring out what Mill has to say about sameness in sense second.
"While speaking of resemblance, it is necessary to take notice of an ambiguity of language, against which scarcely any one is sufficiently on his guard. Resemblance, when it exists in the highest degree of all, amounting to undistinguishableness, is often called identity, and the two similar things are said to be the same. I say often, not always; for we do not say that two visible objects, two persons, for instance, are the same, because they are so much alike that one might be mistaken for the other: but we constantly use this mode of expression when speaking of feelings; as when I say that the sight of any object gives me the same sensation or emotion to-day that it did yesterday, or the same which it gives to some other person. This is evidently an incorrect application of the word same; for the feeling which I had yesterday is gone, never to return; what I have to-day is another feeling, exactly like the former, perhaps, but distinct from it; and it is evident that two different persons cannot be experiencing the same feeling, in the sense in which we say that they are both sitting at the same table. By a similar ambiguity we say, that two persons are ill of the same disease; that two persons hold the same office; not in the sense in which we say that they are engaged in the same adventure, or sailing in the same ship, but in the sense that they fill offices exactly similar, though, perhaps, in distant places. Great confusion of ideas is often produced, and many fallacies engendered, in otherwise enlightened understandings, by not being sufficiently alive to the fact (in itself not always to be avoided), that they use the same name to express ideas so different as those of identity and undistinguishable resemblance."[60]