The thesis of this book is that Kant employs a single conception of reason throughout his analysis of the fundamental principles of natural science, morality and politics, rational religion, and the practice of philosophy itself, and that this conception is that reason is the source of the ultimate goals or ideals for our conduct of both inquiry and action, but never a faculty that yields cognition of objects that exist independently of us, whether sensible or supersensible. In Neiman’s words, “The (...) basis of Kant’s reconception” of reason “is the denial that the rational is, or is centrally concerned with, the cognitive”, and the heart of his thesis of the unity of reason is his view that “the regulative principles of reason... shape our actions in science, morality, religion and philosophy itself”. Neiman’s work is refreshingly ambitious in its attempt to demonstrate that these generalities hold for all four of the areas she lists, but the general claims themselves will not come as a surprise to contemporary students of Kant. So for the work to succeed, it would have to break new ground in either the detailed analysis of the regulative functions of reason or in our understanding of reason’s general function in unifying the several branches of philosophy as Kant understands it. In my view, the book does neither. Neiman offers some interesting insights about Kant’s treatment of science, morality, and religion, but does not offer a rigorous analysis of the structure of Kant’s thought in any of these areas that goes beyond what many others have already provided. More importantly, she misses the opportunity to make a major advance in our understanding of the general structure of Kant’s thought. For what she describes is really similarities in our use of reason in the various areas of our inquiry and conduct; she does not show how Kant uses his conception of reason to unify the apparently disparate realms of theory and practice, or, in his terms, of nature and freedom. This task dominates the Critique of Judgment, where, far from merely recapitulating his previous accounts of the regulative use of reason in both science and morality, Kant argues as he never did before that we must be able to see the realms of nature and freedom not merely as compatible but as unified, yet also makes explicit the regulative status of reason and of this vision of unity precisely by stating his theory of the unity of reason as the culmination of a theory of reflective judgment. Neiman largely ignores Kant’s own most mature account of the unity of reason. (shrink)