Three Puzzles in Frege’s Theory of Truth

Abstract

I want to discuss three related puzzles that arise from Frege’s numerous discussions of truth. The first concerns his thesis that truth is indefinable. Frege includes the thesis that “What true is, I hold to be indefinable” (Was wahr sei, halte ich für nicht erklärbar) among his Kernsätze, his “17 Key Sentences on Logic”. The Kernsäze are dated “1906 or earlier” in the standard edition of his Posthumous Writings (Frege 1979, p. 174), but Dummett has argued (Dummett 1981, p. 523) that they should be dated much earlier, around 1880. Dummett’s reasons for the early date include the hypothesis that the Kernsätze express Frege’s reaction to Lotze’s Logic (Lotze 1884). Now it was, of course, Sluga who first raised the question of the relationship between Frege and Lotze, and, in effect anticipating Dummett’s re-dating of the Kernsätze he maintained that Frege’s thesis of the indefinability of truth is simply an extension of Lotze’s criticisms of the correspondence theory of truth (Sluga 1980, p. 114). Dummett has argued that this seriously misrepresents Frege (Dummett 1981, p. 526); but as long as it is recognised that Frege’s line of thought goes well beyond Lotze’s conclusion, it does no harm to approach Frege’s position via that of Lotze. Lotze’s argument (Lotze, sections 305-6) is essentially epistemological: he argues that, confronted by sceptical doubts about the truth of our beliefs, a correspondence theorist’s advice that we should find out whether our beliefs correspond to the facts is useless -- for in inquiring what the facts are, all we acquire are further beliefs, which we have as much, or as little, reason to doubt as we had to doubt our original beliefs.