The essay describes the relationship between Kant’s Critique of Madness written in the 1760s and his Critique of Reason dating from the 1780s. It attempts to reconstruct the systematics of Kant’s so-called Critical Turn, starting with his Essay on the diseases of the head (1764) and his Dreams of a Spirit-Seer (1766), through the First grounds of the difference of the regions in space (1768) and the Inaugural-Dissertation (1770) up to his Critique of pure Reason (1781/87). The essay points out the way in which Kant applies his psychological insights to philosophy. Via his theory of hallucination, he arrives at the insight that all knowledge is based on projections. Starting with this premise, he examines the objective and subjective basis of rational projection, i.e. apriori reason. Again, he relates the knowledge of projection to philosophy in his examination of projections in logical judgements based on Leibniz’ axioms. This leads him to the detection of three types of logical errors in logical judgement: amphibolia, paralogism, and antinomia. With the latter, his early theory of madness was integrated in philosophy. This essay points out some of the central ideas of my book, Wahn und Wahrheit. Kants Auseinandersetzung mit dem Irrationalen (Akademieverlag, Berlin 2007).
