This study develops an internal critique of Kant's transcendental idealism. To understand the object and significance of this critique requires understanding Kant's unique kind of idealism. Debates about the nature of Kant's idealism are legion. Resolving them adequately requires a broader and more detailed perspective on Kant's philosophical project, and on the key metaphysical view Kant believed undergirded his project, namely his transcendental idealism. This is the main task of the present chapter.
The lead question of Kant's first Critique, indeed his whole Critical philosophy, is “How is Metaphysics as a Science Possible?” (Prol. §60, 4:365.7). Neo-Kantian and recent Anglophone interpretations of Kant's epistemology have concentrated on the Transcendental Analytic of the first Critique, and have taken Kant's positive and legitimate sense of metaphysics to concern the necessary conditions of our knowledge of mathematics, natural science, and commonsense knowledge of a spatiotemporal world of objects and events. However, in the Canon of Pure Reason Kant indicates directly that, although two of the leading subquestions of metaphysics, “What should I do?” and “What may I hope?,” cannot be answered on theoretical grounds, they may be answered on practical grounds (A804–5/B832–3, 3:522.15–34). Those practical grounds are elaborated in the Dialectic of the first Critique, the latter two Critiques, and the Religion.
In either case, whether theoretical or practical, a definite and positive answer to a metaphysical question involves giving “objective reality” to a concept, including, for example, the concepts of freedom or immortality.