man is both sovereign and subject, and this has its parallel in Kant. The volonté générale becomes the 'intelligible world.' Rousseau, by his assertion of the rights of the individual and by his discussion of the relation between the individual and society, influenced Kant and through him the thought of the following century.
In the Critique of Pure Reason, Kant sets up the law of contradiction as the supreme principle of all analytic judgments. In some of his earlier works the law of identity was the principle of affirmative, and the law of contradiction the principle of negative, judgments. Now the principle of identity is a criterion of the truth of affirmative analytic judgments, but the principle of contradiction is not a criterion of truth but of falsehood, and is applicable only to contradictory affirmative, and not to negative, judgments. The principles of identity and contradiction do not suffice for negative judgments. For these we require two other principles: (1) 'contradictory opposites cannot both be true;' (2) 'contradictory opposites cannot both be false.' These latter principles do not show the truth or falsity of a judgment considered in itself, but only in comparison with another judgment whose truth or falsity is already known. They may be called, therefore, relative criteria, as opposed to identity and contradiction which are absolute. These results are founded on the supposition that there are affirmative judgments which are both analytic and contradictory. Analytic judgments seem to resolve themselves into the tautologies. But it is sufficient to refer to the fact that two contents may be objectively the same but subjectively, i.e., in apprehension, different. When, e.g., we say a triangle has three angles, we have a real analytic judgment, since the apprehension of three angles is different from that of three sides; but a triangle in having the one has also the other. Kant supposed a judgment could not be analytic if formed from a consideration of the object. But this does not follow from his definition. This demands only that the consideration of the object be limited to the constituent elements of the concept. As to the contradictory affirmative judgments, we must mention that there are predicates which need only to be brought together in order to see that they cannot be united in the same object. Take for example the proposition 'Blue eyes are black.' While Wolff and his successors ascribed these logical laws to things, Kant denies to them that ontological significance. They are laws of thought. When Kant denies that logic is an organon which instructs us about things as such, he is thinking of synthetic knowledge. Logic is not an organon in which the principles of identity and contradiction free us from a consideration of objects. For, to make an analytic judgment, we must consult the object, and the only difference between analytic and synthetic judgments is that in the latter we go beyond the constituent content of the concept of the subject.
