"Function and Concept" (German: "Funktion und Begriff", "Function and Concept") is a lecture delivered by Gottlob Frege in 1891.
[1] The lecture involves a clarification of his earlier distinction between concepts and objects.
Frege draws an important distinction between concepts on the basis of their level.
Frege tells us that a first-level concept is a one-place function that correlates objects with truth-values (147).
has the value the True with the argument the object named by 'Jamie' if and only if Jamie falls under the concept
correlates the relation of identity with the True.
The conceptual range (Begriffsumfang in Frege 1891, p. 16) follows the truth value of the function: