 Underlying the difficulty of synthesizing and interpreting Kant’s account of reason is, of course, the enormous question of what reason is. Many philosophers—both contemporary and historical figures—proceed as if this were already clear. However, once this question is raised—the question of reason’s self-knowledge, as Kant puts it—it is difficult to see grounds for such confidence. While the secondary literature discussing her proposal remains limited, O’Neill’s interpretation of Kant represents an ambitious and distinctive answer to this question. 