This article accounts for how Kant’s understanding of enlightenment gives normative, communicative structure to public reason as a practice. Kantian public reason is argued to be collegial. As public reasoners promoting our enlightenment, we should seek optimal scrutiny from a generally unrestricted, intellectually and epistemically diverse audience. To receive this scrutiny, we should communicate in a way that facilitates this audience’s ability to scrutinise our views – situating others as our colleagues – which in turn facilitates their promotion of their (...) own enlightenment. As a practice in which we help others promote their enlightenment by helping them help us promote ours, Kantian public reason is argued to be cooperative. But intriguingly, Kant offers a sufficient justification for this cooperative communication on first-personal grounds. The article details some of Kant’s more concrete thoughts on how we should communicate as public reasoners, and concludes by appraising his parsimonious justification of collegial communication as a resource for addressing contemporary concerns about public discourse. (shrink)