or else to turn his attention to himself, as is done with a man distracted, or one suffering mental derangement. The second is possible, but not the first. Whoever denies all principles, that of contradiction included, makes all argument impossible; in vain then will you reason with him. Let us see.
You think, one may say to him, at least you so assert, when you admit the principle I think. True. Then you must also admit the principle of contradiction. Why so? Because otherwise you could think and not think at the same time. Very well. But then you destroy your own thought. How? Is it not true that you think? Certainly. According to yourself it is possible that at the same time you do not think. I agree with you. Therefore, you destroy your thought; for if you do not think, the I think is destroyed, and, as all this is simultaneous, you destroy your own thought.
Not at all. What I object to in your system is that you suppose true the very thing which I deny, and so fall into the sophism named by logicians petitio principii. By the very fact of my denying the principle of contradiction, I deny that not-being destroys being, and that being destroys not-being; consequently, I do not admit that the I do not think destroys the I think. When you argue against me in this way, you suppose the very point in question, and attack me with principles which I do not admit. In your system, in which being destroys not-being, and vice versa, it is certain that to think, and not think, are incompatible; but on my principles, it is a very simple thing; since, according to them, it is not impossible for the same thing to be and not be at the same time, when I do not think, I do not cease to think. This is indeed absurd, but not illogical; deny the principle, and the deduction is necessary. And if it be said that in such a case he cannot reason, as he just has reasoned, he may reply that neither can his adversaries reason; or, if you choose, he sees no difficulty in their both reasoning and not reasoning.
Observation is the only means of bringing back one who has thus strayed away; such a one has departed from reason, and cannot be brought back to it by means of reason. Observations directed to him must be more of a call, a sort of alarm to arouse reason, not a combination to re-construct it: he is as a man asleep, or one in a swoon, and we must call him, and shake him, in order to arouse him; we must not dispute with him as with an adversary.(19)
CHAPTER XX.
TRUE SENSE OF THE PRINCIPLE OF CONTRADICTION.—KANT'S OPINION.
189. Before examining the value of the principle of contradiction as a basis for our cognitions, it will be well to fix its true and exact sense. This renders necessary some considerations upon an opinion of Kant, advanced in his Critic of Pure Reason, when treating of the form in which the principle of contradiction has hitherto been enunciated in all schools of philosophy. The German metaphysician grants, that whatever may be the matter of our cognitions, and in whatever manner they may relate to their object, it is a general, although a purely negative, condition of all our judgments, that they should not mutually contradict each other; otherwise, even without reference to their object, they are nothing in themselves. This doctrine established, he observes that what is called the principle of contradiction is the following: "A predicate that is opposed to a subject does not belong to it;" and then goes on to say, that this is a universal, although purely negative criterion of all truth; that it moreover belongs exclusively to logic, since it is of use to pure cognitions as to cognitions in general, without relation to their object, and he declares that the contradiction makes them completely disappear. "But of this celebrated principle, although stripped of all contents, and purely formal," he continues, "there is still a formula containing a synthesis, which has inadvertently, and quite unnecessarily, been mixed up therein. It is this: It is impossible for the same thing to be and not be at the same time. Not only has the apodictic certainty (by the word impossible) been unnecessarily added, which certainty would have been of itself understood from the proposition; but the proposition is affected by the condition of time, and says, as it were: a thing = A, which is something = B, cannot at the same time be not B, but it can very well be both (B as well as not B) in succession. For example: a man who is young, cannot at the same time be old; but the same person may very well be young at one time, at another not young, that is, old. Now, the principle of contradiction, as a mere logical principle, must not at all restrict its meaning to the relations of time, and consequently, such a formula is quite opposed to its intention. The misapprehension arises simply from this: that we first separate the predicate of a thing from its conception, and afterwards unite its opposite with this predicate, which never gives a contradiction with the subject, but only with its predicate, which is synthetically joined with that subject, and that only when the first and second predicates are asserted at the same time. If I say a man who is unlearned is not learned, the condition, at the same time, must be expressed; for he who is unlearned at one time may very well be learned at another. But if I say no unlearned man is learned, the proposition is analytic, since the sign (the unlearnedness) now constitutes the conception of the subject, and then the negative proposition is evident immediately from the principle of contradiction, without it being necessary for the condition, at the same time, to be added. This is also the cause why I have so changed the formula of this principle, that the nature of an analytic proposition might be clearly expressed."[16]
190. The reader will not easily comprehend the meaning of this passage, not very clear of itself, unless he knows what Kant understands by analytic and synthetic propositions. We will explain this. In all affirmative judgments, the relation of a predicate to a subject is possible in two manners: either the predicate belongs to the subject as contained in it, or is completely extraneous to it although joined with it. In the former case, the judgment is analytic; in the latter, it is synthetic. Analytic affirmative judgments are those in which the union of the predicate with the subject is conceived by identity: those are called synthetic in which this union is conceived without identity. Kant illustrates his idea by the following examples: "When I say all bodies are extended, I express an analytic judgment; for I need not go out of the conception of body in order to find that of extension, which I connect with it, but I have only to analyze the conception of body, that is, to become conscious of the diversity which I always think in this conception, in order to find the predicate. It is, therefore, an analytic judgment. But when I say, all bodies are heavy, the predicate heaviness is by no means included in my conception of the subject, that is, of body in general. It is a conception added to the conception of body. The addition in this way of the predicate to the subject gives a synthetic judgment."[17]
It is easy to see the reason of the new nomenclature employed by the German philosopher. He calls those judgments analytical, in which it suffices to decompose the subject to find therein the predicate, without the necessity of adding any thing not already thought, at least obscurely, in the very conception of the subject; and he calls synthetic those in which it is necessary to add something to the conception of subject, since the predicate is not found in this conception however much we decompose it.
191. This division of judgment, into analytic and synthetic, is much used in modern philosophy, above all among the Germans; certainly there are some who may imagine this to be a discovery made by the author of the Critic of Pure Reason; and the very novelty of the name may give occasion to equivocation. Yet, in all the scholastic writers who lie forgotten, and covered with dust, in the recesses of libraries, we find analytic and synthetic judgments, though not under these names. They said there were two kinds of judgments; some, in which the predicate was contained in the idea of subject, and others, in which it was not. They called the propositions which expressed judgments of the former class, per se notæ, or known by themselves, because, the meaning of the terms being understood, the predicate was seen to be contained in the idea, or the conception of the subject. They also called them first principles, and the perception of them, intelligence, intellectus, to distinguish them from reason, which is conversant about the cognitions of mediate evidence, or ratiocination.
See
