The hierarchy of functions

pp. 44-57

in: Christian Thiel, Sense and reference in Frege's logic, Berlin, Springer, 1968

Abstract

As Frege set about to carry out the logical construction of arithmetic in a strictly ideographic way in the Basic Laws of Arithmetic, his logical views had significantly progressed over those of the Begriffsschrift and Foundations. The change is so decisive that commentators — like Bierich, Papst, Scholz, etc. — can talk about a "second period" in Frege"s thought, beginning about 1890. This division is undoubtedly justified, and is not contradicted by the aspect of continuity in Frege"s work — an aspect which we have utilized in our present discussion of specific problems. And the limitation to two periods is justified by the fact that other changes in the views of Frege were of only secondary importance.