Modal Adventures between Leibniz and Kant: Existence and (Temporal, Logical, Real) Possibilities

This paper explores the philosophical transitions in the relations between existence and possibility in Leibniz and Kant. It begins with Leibniz’s formulation of a strictly logical notion of possibility; proceeds with Kant’s pre-critical statement in 1763 that existence is not a predicate; and ends with the Critique of Pure Reason in which the theory of possibility is constrained by the subjective conditions of experience (to supply the material for thinking possibilities) and is thus relativized to the human mind. I present Leibniz’s view of possibility against the traditional view of temporal modalities; and, in this light, his dual notion of existence. I then argue that, in Kant’s pre-critical essay of 1763, the view that existence is not a predicate is strongly related to the logical view of possibility advanced by Leibniz. I conclude with Kant’s transition to the critical period and its implications on the analysis of modality