Kant conceived of ‘critique’ as a kind of winnowing exercise, with the aim of separating the wheat of good metaphysics from the chaff of bad. He used a less familiar metaphor to make this point, namely, that of ‘the fiery test of critique’-not a medieval ordeal of trial by fire, but rather a metallurgical assay, or cupellation, a procedure in which ore samples are tested for their precious-metal content. When seen in this light, critique has a positive, investigatory side: it seeks not merely to eliminate bad, ‘dogmatic’ metaphysics but also to uncover what of philosophical value might be contained in traditional speculative metaphysics. In this comprehensive study of the Transcendental Dialectic in Kant’s Critique of Pure Reason, Proops argues that Kant uncovered two nuggets of value: the indirect proof of Transcendental Idealism afforded by the resolution of the Antinomies, and a defence of theoretically grounded ‘doctrinal beliefs’ in a wise and great originator, on the one hand, and in an afterlife, on the other. This examination of critique engages with Kant’s views on a number of central problems in philosophy and meta-philosophy: the explanation of the enduring human impulse towards metaphysics, the correct philosophical method, the limits of self-knowledge, the possibility of human freedom, the resolution of metaphysical paradox (‘Antinomy’), the justification of faith, the nature of scepticism, and the role of ‘as if’ reasoning in natural science.