Abstract

For Kant one of the goals of any critique of pure reason is to answer the question, how are a priori synthetic propositions possible? Because rationalists such as Eberhard and Wolff took the principle of sufficient reason (hereafter, the PSR) as the principle of all a priori synthetic judgments, understanding both the various formulations of this principle and arguments in favor of its use as an axiom in metaphysical reasoning provides an interesting back door to understanding The Critique of Pure Reason. Despite his statements in the First Critique rejecting the PSR as a principle of judgment1, I argue that Kant was actually more sympathetic to the PSR than these passages alone would suggest. The Kant-Eberhard Controversy suggests that, even though Kant explicitly denies that the PSR can guide metaphysical reasoning, he actually presupposes its truth. I show that Kant’s position is tenable because, like the rationalists, Kant accepts the assumption that real essences exist and that they ground real possibility2; this leads him to accept the truth of all clear statements of the PSR. Unlike the rationalists, however, he does not accept the assumption that human understanding is isomorphic with real essences. As a result, Kant rejects only the use of the PSR to determine a priori the existence or properties of a thing. In this paper I hope to illuminate this position. I will begin with a survey of the various formulations of the PSR that have been put forward by Kant and his predecessors: Leibniz, Eberhard, and Wolff. Then I will examine Wolff and Eberhard’s arguments in favor of the PSR along with Kant’s criticisms of these arguments. Lastly, I will show why Kant rejected the very possibility of justifying this use of the PSR while presupposing its truth.