 Kant describes a concept as a “function” (Funktion), which he characterizes as “the unity of the act through which different representations are ordered under a common one” (A68/B93). Concepts are merely “predicates of possible judgments” (A69/B94) “grounded on the spontaneity of thinking” and the faculty of understanding “can make no other use of these concepts than that of judging by means of them” (A68/B93).