204 ARTHUR O. LOVE JOY : Laas has already raised the inquiry whether Kant regarded the principle of contradiction in general as a valid criterion of the nature of reality an sich ; and he has justly insisted that the point is one of capital importance. 1 " Upon a philo- sopher," Laas observes, "who places between our world of time and space and the world of reality as such a chasm so wide and deep that for the latter the most conflicting possibilities remain open, it is decidedly incumbent to give a definite answer to such questions as these : Is the formula (of the impossibility of the self-contradictory) valid ' only in relation to a sensuous perception ' ? Is its extension to things in themselves inadmissible ? Does it apply only to phenomenal existence? For who would venture to declare that there are other forms of being besides those known to us, and then deduce from the mere concept of Being the conclusion that all Being must be free from self-contra- diction ? " Important these questions certainly are ; but there can be no doubt about Kant's answer to them. His declaration on the subject is precisely the declaration of which Laas speaks. In both the earlier and the later period of his thinking, Kant adhere; consistently to the view that an object in which self- contradictory predicates are said to be united is not truly an object of thought at all, but a mere nihil negativum irreprasentabile. In his earliest philosophical writing, the Dilucidatio Nova, Kant, in criticising the customary Wolman way of formulating the principle of contradiction expresses only the more clearly his recognition of the importance of that principle in metaphysics. Under the name of a single formula, he maintains, philosophers have really been making use of two distinct principles, namely, impossibile est idem esse ac non esse and cujuscumque op- positum est falsum, illud est verum. These two are not, Kant thought, reducible to one another ; but they are equally and independently valid. As an instrument of philosoph- ical proof the latter is the more important. In the essay on the Idea of Negative Magnitude Kant declares that the self- contradictory is gar nichts ; and in the paper on " The Only Possible Ground for a Demonstration of the Existence of God " he writes : " All that is self-contradictory is inherently impossible. . . . This logical repugnancy I call the formal character of inconceivability ( Undenklichkeit') or impossibility." Similar expressions are abundant in the writings of the so- called critical period ; e.g., from the Reply to Eberhard : " what- ever does not agree with this principle (of contradiction) is 1 Kant's Analogien dcr Erfahrung, p. 33.
