The Unity of Reason is the first major study of Kant's account of reason. Susan Neiman argues that Kant's philosophy reconceives the nature of reason, and she shows how that philosophy provides a basis for the unity of theory and practice. Exploring the historical background of Kant's notion of reason, as well as the role of reason in Kant's accounts of science, morality, religion, and philosophy, she provides a fundamentally new perspective on Kant's entire work.