Immanuel Kant
Kant developed his moral philosophy in three works: "Groundwork of the Metaphysic of Morals" (1785), "Critique of Practical Reason" (1788), and "Metaphysics of Morals" (1797).
T. K. Seung
In the Metaphysical Deduction, Kant claims to derive logically his twelve categories from the twelve forms of judgment. It has long been a standard practice to dismiss the Metaphysical Deduction as one of Kant's typical opaque passages and move on to the Transcendental Deduction. Seung argues that this practice leads to a serious misreading of the first "Critique". If Kant were to assemble the categories empirically, they could not be distinguished from empirical concepts. For this reason, he openly disdains Aristotle's empirical method of collecting his categories. By his logical derivation of the categories, Kant believes, he can prove their a priori origin because logic is a priori. With their a priori origin thus proven, Kant intends to use them as the logical premise for the Transcendental Deduction. But Seung shows that Kant's derivation scheme was ill-conceived. The forms of judgment are syntactic elements; the categories are semantic elements. To derive the latter from the former was to derive semantic elements from syntactic elements. Although this was a logically impossible operation, Kant proudly flaunted it as his ingenious invention. Unfortunately, his ingenuity thrived only in exploiting his logical fantasy. Seung has dissected a series of fraudulent maneuvers in his derivation of the categories. But the fraud was recognized neither by the performer nor by the audience because it was executed in an obscure tricky language.