Tackles the two main issues of contention between Cassirer's and Heidegger’s interpretations of Kant. I first examine why Heidegger opposes his own ‘ontological reading’ of the first Critique to the ‘epistemological reading’ that he attributes to the Neo-Kantians. I clarify what this opposition entails and consider in what way it indeed applies to Cassirer (4.1). Next, I turn to Cassirer and Heidegger's more specific disagreement regarding the relevance of Kant's account of transcendental imagination. Remarkably, both thinkers not only value how this account attempts to undercut the artificial opposition between receptivity and spontaneity (4.2), but their agreement extends to the shared thesis that Kant ultimately did not succeed because he lacked a truly phenomenological method (4.3). Yet, Cassirer and Heidegger still radically part ways as soon as they evaluate why this (failed) attempt is so important: while Heidegger takes transcendental imagination as the ground of human reason’s finite nature, Cassirer concludes from the primacy of this faculty to the fundamentally spontaneous character of reason (4.4).

Focusing on its 1781 version, Chapter 5 interprets the transcendental deduction in light of Kant’s overall investigation into the conditions under which metaphysics is possible. Whereas most commentators take the text to be mainly concerned with the conditions of possibility of empirical cognition, it seeks to demonstrate that the various strands of Kant’s investigation primarily aim to identify the conditions under which categories can be used to produce objects of a priori cognition as such. On Kant’s account, categories can contribute to the production of such objects only if they function as a priori rules for the thoroughgoing unification of successive representations, which is not the case if they are used to determine alleged objects such as the soul, the world as such, and God. Thus, I contend that the transcendental deduction passes a balanced judgment on Wolff’s unqualified affirmation of the possibility of a priori cognition of objects and Hume’s unqualified rejection of the same.