Page:Mind (New Series) Volume 15.djvu/209

KANT'S ANTITHESIS OF DOGMATISM AND CRITICISM. 195 principle of contradiction or, to give it a name that better -covers their full meaning, the principle of the compossibility of concepts. There had, moreover, during the period just before the appearance of the critical philosophy, been taking place a progressive clearing up of the significance and scope of this principle, and an especially determined effort to elucidate the whole question of the nature of a priori judgments. Since this was the case it will be of use to inquire, first, just what Leibniz and Wolff meant by the principle of contradiction, especially in its relation to the question of " the possibility of synthetic judgments a priori " ; and, second, to ascertain precisely what Kant's own views were about the validity and the reach of that principle. We shall find the results of such an inquiry somewhat surprising. The principle of sufficient reason is still sometimes repre- sented as holding in the Leibnitian system an independent place, virtually co-ordinate with the principle of contradiction. But in reality Leibniz fully recognised that this principle can apodictically establish no conclusions a priori ; and Wolff either treated it as a special case of the principle of contra- diction, or else attempted to justify it by a peculiar mode of argument, of which Kant would have been obliged to recog- nise the legitimacy on strictly ' critical ' grounds. With the" ^exception, then, of this last-mentioned argument, which can- not be dealt with here, Leibniz and Wolff rested the whole possibility of demonstrative proof or disproof in metaphysics upon the principle of contradiction, and professed to have no metempirical theoretical knowledge save such as could be_ gained through the use of that principle. Wolff takes pains to point out that even the Cartesian cogito ergo sum is nothing more than a special case of the sort of logical necessity which the principle establishes. What, then, did these philosophers understand by the 'Grund des Widerspruches ? We must remember, to begin with, that Leibniz a fact of which both Mr. Bertrand Russell and M. Couturat have made much, in their recent expositions of his doctrine liked to call all judgments analytical, contingent ones no less than necessary ; this because of the familiar truth of formal logic that the connotation of the predicate of a proposition is always embraced within the connotation of the subject. As M. Couturat points out, the whole metaphysics of Leibniz Erkenntnissvermogen ". Upon this Kant remarked that, if such was the -case then, indeed, " there is no dogmatism in that philosophy, in the sense in which our Kritik always employs the word" (Reply to fiberhnl, !* Abschn).