"Having of a long time experienced certain ideas perceivable by touch—as distance, tangible figure, and solidity—to have been connected with certain ideas of sight, I do, upon perceiving these ideas of sight, forthwith conclude what tangible ideas are, by the wonted ordinary course of nature, like to follow. Looking at an object, I perceive a certain visible figure and color, with some degree of faintness and other circumstances, which, from what I have formerly observed, determine me to think that if I advance forward so many paces, miles, etc., I shall be affected with such and such ideas of touch."[54]
And need one ask a clearer illustration of sameness in sense third than the case of the coach, which occurs in the following section:
"Sitting in my study I hear a coach drive along the street; I look through the casement and see it; I walk out and enter into it. Thus, common speech would incline one to think I heard, saw, and touched the same thing, to wit, the coach. It is, nevertheless, certain the ideas intromitted by each sense are widely different and distinct from each other; but, having been observed constantly to go together, they are spoken of as one and the same thing."
Sec. 30. It would be easy to select from Spinoza, that master of reasonings apparently very exact but really very loose, many good instances of confused samenesses. I shall confine myself to a single one, his argument to prove that every substance is necessarily infinite. It is the eighth proposition in Part I of the Ethics.
"There cannot be more than one substance with the same attribute, and this exists of its own nature. It belongs, then, to its nature to exist either as finite or as infinite. But it cannot be finite, for then it would have to be limited by another of the same kind, which would also necessarily exist; there would then be two substances with the same attribute, which is absurd. It is, therefore, infinite."[55]
Among its defects this argument includes a confusion of sameness in sense fourth with sameness in sense first. Attribute Spinoza has defined as that which is conceived as the essence of substance. Mode is a modification of substance. Two substances, he has argued, cannot be distinguished from each other by their modifications, for substance is prior to its modifications, and we may set these aside and consider it as it is in itself. Substances cannot then, be distinguished except by their attributes; and if the attribute be the same, how can we say that there are two substances? There cannot, consequently, be two substances with the same attribute.
But, the argument continues, since there cannot be two substances with the same attribute, every substance must be infinite; for, to be finite, a thing must be limited by something: and nothing can be limited except by a thing of the same kind (for example, a material thing cannot be limited by a thought). But if a thing be limited by another thing of the same kind, the thing limited and the thing limiting have the same attribute. It follows that they are not two things, but one. The thing in question is not limited but infinite.
In criticizing this, I may call attention, in passing, to the highly disputable and gratuitously assumed premise, that, to be finite, a thing must be limited by something. If this be denied, the ground of the reasoning is removed; while, if it be granted, no argument is needed to prove that something is infinite, for one has only said in other words that all limits must be limits within something. The question is begged at once. With this, however, I am not concerned. What interests me is this: The argument assumes a limited thing and a something beyond it, and then asserts that they are one. But two things of the same kind in different places, or marked as different by distinctions of any sort, are readily distinguished as two. To come to the concrete, extension conceived as on this side of a point and extension conceived as beyond the point are not extension simply, but "this" extension and "that" extension. They are the same only in sense fourth, not in sense first. We have here not merely the attribute extension, but the further elements "this" and "that." The conclusion, then, that what we started out with is infinite, is wholly unwarranted. It is not this that is infinite, but this with something else which is to some degree like it, although not wholly so. That is to say, the thing assumed as finite can only be proved to be infinite by confounding two samenesses. The thing proved to be infinite is a new object including it and what it is assumed to presuppose. If it be not permissible to make this distinction between the object assumed as finite, for the sake of the argument, and the object which is proved to be infinite, it is also not permissible to assert that an object to be finite "would have to be limited by another of the same kind." If the two are one, these words are meaningless. If they are not one, one cannot conclude from the argument that every substance is necessarily infinite, but only that something is necessarily infinite, a conclusion already given in the single premise that what is limited must be limited by something of the same kind. As a matter of fact, Spinoza retains in his argument not only the attribute, but the mode, the "this" and the "beyond this;" and then he overlooks the mode and considers merely the attribute, which gives him strict identity. This procedure we have met before in the dispute concerning universals.
Sec. 31. In the former part of my monograph I have mentioned Locke's confusion of sameness in sense seventh with sameness in sense first. I shall now quote a few sections from the "Essay concerning Human Understanding" to show how significant his error is, and to what an extent it is responsible for his position regarding ideas, things, and substance. My extracts are from the eleventh chapter of the fourth book, entitled "Of our Knowledge of the Existence of Other Things." Locke argues as follows:[56]
"The knowledge of our own being we have by intuition. The existence of a God reason clearly makes known to us, as has been shown.