I shall first answer the second clause of this allegation, and then speak to the charge that I have confounded the provinces of logic and metaphysics.
It is not true that I attempt to reach real existence by demonstration. I assume real existence; I take for granted that there is something. I assume this; and I care not what the grounds of the assumption may be called. I will call these grounds by any name Mr Cairns pleases,—belief, knowledge, intuition, simple apprehension, "mental assertion," as he phrases it; or, if he likes it better, let there be no grounds at all for the assumption. Suffice it to say, I assume that something is. This I have stated in the most explicit terms in the following passages. "The science (metaphysics) is not called upon to prove either that absolute existence is, or that it is not the contradictory. It takes and must be allowed to take this for granted" (Institutes, p. 465, 2d Ed.). A demonstration is indeed supplied, proving that absolute existence is not the contradictory, although this also might have been assumed. But, that something really and absolutely exists—this is neither demonstrated in my work nor attempted to be so. This statement, then, is clearly a misrepresentation on the part of the Town Council's assessor, Mr Cairns—a misrepresentation made in the face of my most obvious statements.
What, then, do I attempt to prove in regard to real existence? for, surely I attempt to demonstrate something about it. To be sure I do—I endeavour to prove, and I do prove most cogently what it is, not that it is. Attention to these two words, what and that, may serve to explicate the confusion into which Mr Cairns has run. Suppose that some new and very peculiar animal were discovered—an animal which lived sometimes on the land, sometimes in the sea and sometimes in the air; and suppose that certain naturalists were employed to investigate its nature. Would they require to prove in the first instance, that such an animal was? Certainly they would not? There it is before them, and that surely is enough. They would merely have to ascertain what it was. Is it fish, flesh, or fowl? The what here might be a nice point of inquiry, while the that would be an insane one.
