Kant’s Account of Real Possibility and the German Philosophical Tradition

Kant’s postulate of possibility states that possible is whatever agrees with the formal conditions of experience. As has often been noted, this is a definition of real possibility. However, little attention has been paid to the relation of Kantian real possibility to the German philosophical tradition before him. I discuss three kinds of possibility present in this tradition – internal, external, and (Crusian) real possibility – and argue that Kant endorses internal and external possibility. Furthermore, I show, specifically with respect to the concept of state (Zustand), that the three traditional conceptions are reminiscent of three conceptions of real possibility that Kant implicitly distinguishes. Lastly, I argue that, according to Kant, we need experience to prove real possibility (at least as regards the three conceptions of the real possibility of states) because otherwise we could not know whether the formal conditions of experience obtain.