In The Philosophical Criticism, Alois Riehl developed a realistic interpretation of Kant’s transcendental idealism based on his theory of space and time. In doing so, more than 100 years ago, he formulated an interpretation of the relation between the thing in itself and appearances that is discussed in current research as the metaphysical „dual aspect“ interpretation, although it is rarely attributed to Riehl. To reconstruct Riehl’s position, the research results of comparative studies on Moritz Schlick are systematically extended and applied (...) to the current debate on Kant’s transcendental idealism. (shrink)