Kant wrote two versions of the Transcendental Deduction, the first, "A-"Deduction in 1781, and the second, "B-"Deduction in 1787. Since Henrich's "The Proof Structure of Kant's Transcendental Deduction", most work on the Transcendental Deduction attempts to make sense of the B-Deduction's two-step argument structure. Though the A-Deduction has suffered comparative neglect, it has received some attention from interpreters who take its extended treatment of the "subjective" side of cognition to amount to a brand of proto-functionalism. Whatever the merits and demerits of these proto-functionalist approaches, they tend to deemphasize the two arguments that constitute the "objective" side of the A-Deduction, the "argument from above" and then the "argument from below". Since Kant himself refers to this objective side of the A-Deduction as the "Deduction of the Pure Concepts of the Understanding", it is surprising that the structure of these arguments has not received closer scrutiny. This is doubly true since Kant actually claims that his revisions for the 1787 version of the Deduction impacted only the "presentation" of it. Any lessons learned from the central arguments of the A-Deduction should help clarify the structure of its younger and more closely studied brother. © Walter de Gruyter 2001.