Kant's Critical Philosophy and the Thing-in-Itself

Immanuel Kant's three Critiques — the Critique of Pure Reason (1781, revised 1787), the Critique of Practical Reason (1788), and the Critique of Judgment (1790) — set the philosophical agenda that German Idealism would inherit and push further. The most famous move of the first Critique is the so-called "Copernican Revolution," announced in the 1787 B-Preface: rather than assuming that cognition must conform to objects, Kant proposes that objects, as we experience them, must conform to the structure of the cognizing subject. This reversal grounds his central distinction between phenomena — appearances structured by the forms of space and time and by twelve categories of the understanding (unity, plurality, totality, reality, negation, limitation, substance, causality, community, possibility, existence, and necessity, all derived from the table of judgments) — and noumena, things as they are in themselves, which lie beyond the reach of discursive human cognition. The explanatory target of the whole Critical project is the possibility of synthetic a priori judgments, propositions such as "7+5=12" or "every event has a cause" that are both informative and knowable independently of experience, and the Transcendental Deduction argues that the categories are the necessary conditions for any unified experience whatsoever.