Johannes Haag is a professor of theoretical philosophy at the University of Potsdam. His systematic interests in theoretical philosophy concern the philosophy of language, epistemology, the philosophy of mind, and in particular the theory of intentionality. Historically, he works mainly on issues in early modern philosophy, the philosophy of Enlightenment, the philosophy of Kant and German Idealism. In addition to Kant and Descartes, he is especially interested in Spinoza, Berkeley, and Fichte.