This is a specious objection; but it does not remove the difficulties under which the system, in favor of which it is adduced, labors; and it may, on the other hand, be solved in so far as it tends to weaken objective truth.
The madman, the lunatic, have also recollections of things that never existed. These recollections do not relate solely to external, but likewise to their internal acts. The madman who calls himself king, acts in accordance with his thought, with what he felt when crowned, when dethroned; and yet, these intellectual phenomena never existed. And, however this may be, he himself may have produced these recollections. We hold, then, that the criterion with respect to memory is wrong in this case, and can be of avail in no case. Therefore, even, although we had not shown that without objective truth there is no recollection even of the internal, the arguments of our adversaries would have sufficed. This objection, if it prove any thing, confirms all that we have advanced in demonstrating that without objectiveness there is no consciousness properly so called, and this even our opponents do not admit.
263. Moreover, we at once see what weight an argument based on craziness should have at the tribunal of reason. It all, at the most, only proves the weakness of our nature, that in some unfortunate individuals the established order of humanity is reversed; that the rule of truth, as it exists in so weak a creature, admits of some exceptions; but these exceptions are known, for their characters are marked. The exception does not destroy, it only confirms the rule.[(25)]
[CHAPTER XXVI.]
CAN ALL COGNITIONS BE REDUCED TO THE PERCEPTION OF IDENTITY?
264. Immediate evidence has for its objects those truths which the intellect sees with all clearness, and to which it assents without the intervention of any medium, as its name denotes. These truths are enunciated in propositions called per se notæ, first principles, or axioms, in which it is sufficient to know the meaning of the terms to see that the predicate is contained in the idea of the subject. Propositions of this class are few in all sciences; the greater part of our cognitions are the fruit of reasoning which proceeds by mediate evidence. In geometry the number of truths that do not require demonstration, but only explanation, is very limited. The body of geometrical science, with its present colossal dimensions, has proceeded from reasoning: even in the most comprehensive works the axioms occupy but a few pages; the rest is composed of theorems, propositions not of themselves evident, but requiring demonstration. The same is true of all other sciences.
265. Since in axioms the intellect perceives the identity of the subject with the predicate, intuitively seeing that the idea of the latter is contained in that of the former, there arises a very grave philosophical question which may prove very difficult, and cause strange controversies, if care be not taken to place it upon its true ground. Is every human cognition reduced to the simple perception of identity? and can its general formula be this: A is A, or: a thing is itself? Some philosophers of note maintain the affirmative; others the contrary. We think there is a confusion of ideas not so much as to the question itself as to its state. Clear and exact ideas of what judgment is, and of the relation affirmed or denied by it, will greatly facilitate the accurate solution of the question.
266. There is in every judgment perception of identity or non-identity, accordingly as it is affirmative or negative. The verb is does not express the union, but the identity of the predicate with the subject; and when accompanied with the negation not, it simply expresses non-identity, abstracting union or separation. This is so true and so exact, that in things really united an affirmative judgment is impossible, because they have no identity. We must, then, in such cases, if we would be enabled to make an affirmation, express the predicate in the concrete, that is, in some sense involving the idea of the subject itself in it; for the same property affirmed in the concrete cannot be in the abstract, but must rather be denied. Thus we may say, man is rational; but not, man is rationality: a body is extended; but not, a body is extension: paper is white; but not, paper is whiteness. Why is this? Is it that rationality is not in man, extension is not united to body, nor whiteness to paper? Certainly not; but if rationality be in man, extension in body, and whiteness in paper, we have only not to perceive identity between the predicates and subjects, to render affirmation impossible; on the contrary, despite the union, we have negation: thus we may say, man is not rationality; a body is not extension; paper is not whiteness.
We have said that, in order to save the expression of identity, we used the concrete instead of the abstract term, and involved in the former the idea of the subject. It cannot be said that paper is whiteness, but it may be said that paper is white; for this last proposition means that paper is a white thing; that is, we make the general idea of a thing, or the idea of a modifiable subject, enter into the predicate while in the concrete; and this subject is identical with the paper modified by whiteness.