Overview

It is one of Kant's central claims that sensibility and understanding are the only sources of knowledge with which the human cognitive faculty is furnished. In the Critique of Pure Reason, the major work of his transcendental philosophy that is supposed to answer the key question of theoretical philosophy, “What can I know?” (A 804/B 832), Kant writes: “All that seems necessary for an introduction or preliminary is that there are two stems of cognition … sensibility and understanding” (A 15/B 30). This claim is mainly, though not exclusively, directed against the Leibnizians. The Leibnizians concede that sensibility and understanding are in many respects different; however, they assign both of them to a single cognitive capacity, the faculty of representation: sensibility is the faculty of confused representation whereas the understanding is the faculty of clear and distinct representation. According to this view, sensibility and understanding are not essentially distinct sources of knowledge, but rather indicate nothing more than the difference between confused and distinct representation. Since cognition cannot consist in confused representation, the Leibnizians argue, only the understanding is capable of acquiring genuine knowledge by means of clear and distinct representation.

Kant considers the conception of the difference between sensibility and understanding in terms of a psychological graduation from confused to distinct representation to be fundamentally mistaken. He explains why with the help of the following example: