Abstract

Important aspects of its philosophical basis, and its significance for the foundations of mathematics, appeared in The Foundations of Mathematics (FA, 1884). Six years later, at the beginning of the 1890s, Frege published three articles that mark significant changes in his conception: "Function and Concept" (FC, 1891), "On Sense and Reference" (SR, 1892) and "Concept and Object" (1892). Notable among these changes are: (a) The systematic distinction between the sense and the reference of expressions as two separate ingredients of their meaning. (b) The extension and generalization of the notion of function to include the conception of concepts and relations as functions to truth-values, and the corresponding conception of the two truth-values as objects. These changes were immediately incorporated in the mature, authoritative exposition of his logic in his magnum opus: Basic Laws of Arithmetic (BL), whose first volume appeared in 1893