The unconscious raises relevant problems in the theory of knowledge as regards non-conceptual contents and obscure representations. In the philosophy of mind, it bears on the topic of the unity of consciousness and the notion of the transcendental Self. It is a key-topic of logic with respect to the distinction between determinate-indeterminate judgments and prejudices, and in aesthetics it appears in connection with the problems of reflective judgments and of the genius. Finally, it is a relevant issue also in moral philosophy in defining the irrational aspects of the human being. The purpose of the present volume is to fill a substantial gap in Kant research while offering a comprehensive survey of the topic in different areas of research, such as history of philosophy, philosophy of mind, aesthetics, moral philosophy, and anthropology.