  Vaihinger’s rejection of the thing in itself is implicit in the general label he gives to his own philosophical view, “idealistic positivism.” The ‘positivism’ here is in part an epistemological, and in part a metaphysical thesis. The epistemological thesis is that “what is given consists only of sensations” (PAO 124; cf. xxviii). The metaphysical thesis is that “what we usually term reality consists of our sensational contents [Empfindungsinhalte]” (PAO xxx, emphasis added); “Nothing exists except sensations” (PAO 44, emphasis added; cf. 1921a, 532–33). This extreme view (for which Vaihinger does not argue) has the immediate conclusion that all knowledge is of appearances, since nothing exists except appearances.