DEDUCTION

[A84/B116] This term derives from a legal term; Kant writes, "Jurists when speaking of rights and claims, distinguish in a legal action the question of right (quid juris) from the question of fact (quid facti); and they demand that both be proved. Proof of the former, which has to state the right or legal claim, they entitle the deduction". Famously, Kant holds that certain "usurpatory concepts" require a deduction "sufficient to justify their employment, [said deduction] being obtainable either from experience or from reason". [A669/B697] In particular, Kant holds that "we cannot employ an a priori concept with any certainty without having first given a transcendental deduction of it". Presumably different types of deductions are appropriate for different types of concepts; Kant distinguishes subjective and objective deductions, empirical, metaphysical and transcendental deductions, and deductions of categories and of the ideas of pure reason.