Stephen Puryear

I argue that Leibniz's treatment of void or empty space in the appendix to his fourth letter to Clarke conflicts with the way he elsewhere treats (metaphysical) evil, insofar as he allows that God has created a world with the one kind of privation (evil), while insisting that God would not have created a world with the other kind of privation (void). I consider three respects in which the moral case might be thought to differ relevantly from the physical one, and argue that none of them succeed in removing the inconsistency. Rather than denying the existence of void, Leibniz should have been led by his treatment of evil to realize that the arguments he deploys in this appendix are dubious, and that the principles to which he appeals do not rule out empty space any more than they rule out evil, darkness, cold, or any other privations.

I argue that Leibniz's rejection of the hypothesis of thinking matter on grounds of unintelligibility conflicts with his position on sensible qualities such as color. In the former case, he argues that thought must be a modification of something immaterial because we cannot explain thought in mechanical terms. In the latter case, however, he (rightly) grants that we cannot explain sensible qualities in mechanical terms, that is, cannot explain why a certain complex mechanical quality gives rise to the appearance of a certain sensible quality, even while insisting that sensible qualities are modifications of bodies. I argue that the two cases are analogous in the relevant respects, and that Leibniz's (plausible) position on sensible qualities should have thrown his Principle of Intelligibility into doubt.