‘Simplex Sigillum Veri’ and the Question of the Limits of Language

Abstract It is a more or less universally accepted view that, in the Tractatus, Wittgenstein rejects the possibility of syntheticity a priori. While Wittgenstein affirms that logic is a priori, the propositions of logic are tautologies and hence analytic. According to Peter Sullivan, this is enough to show that the Tractatus is not a work committed to transcendental idealism. To count as evidence of transcendental idealism in the Tractatus, the a priori limits of language should be synthetic. So while it may look as though the Tractatus introduces a genuine limitation to thought by contrasting it with feeling, for Sullivan such Kantian integration between Wittgenstein’s theoretical and practical philosophy is ‘too much integration to hope for’ (Sullivan 2013, 265). This chapter argues that such integration may be feasible after all. Drawing on Kant’s transcendental aesthetic, the chapter argues that the Tractatus incorporates at least two types of insights that for Kant would count as synthetic a priori. Acknowledging the connection between the two types of insights allows us to see how the theoretical and practical sides of the Tractatus are connected.