It is traditionally held that our knowledge of necessity is a priori; but the familiar theories of a priori knowledge – platonism and conventionalism – have now been discredited, and replaced by either modal skepticism or a posteriori essentialism. The main thesis of this paper is that Kant's theory of a priori knowledge, when detached from his transcendental idealism, offers a genuine alternative to these unpalatable options. According to Kant's doctrine, all epistemic necessity (which he calls “conviction” (Ueberzeugung) is grounded directly or indirectly on our capacity for clear and distinct rational intuition (which he calls “insight” (Einsicht). Insight, in turn, depends upon functions of the imagination for creating “mental models” of necessary truths. This doctrine is well exemplified by Kant's account of our knowledge of simple analytic truths.