Localizing Violations of the Principle of Sufficient Reason—Leibniz on the Modal Status of the PSR

Abstract

The Principle of Sufficient Reason (PSR)-the principle that everything has a reason-plays a central role in Leibniz's philosophical system. It is rather difficult, however, to determine what Leibniz's attitude towards the modal status of the PSR is. The prevailing view is that Leibniz takes the PSR to be true necessarily. This paper develops a novel interpretation and argues that Leibniz's PSR is a contingent principle. It also discusses whether a merely contingent PSR can do the metaphysical heavy lifting that Leibniz aims for. The paper shows that, despite appearance to the contrary, this is possible. In a nutshell, the argument is that the only possible PSR violation Leibniz allows for is God's creation of a suboptimal world; there is no Leibnizian possible world, though, which intrinsically violates the PSR. Despite its contingency, then, Leibniz's PSR is modally robust enough to serve as a foundational principle of his metaphysics.