 As it happens, anti-verificationism has two aspects: opposition to meaning reductionism and opposition to the formalist project. Turning to the former, we must distinguish two forms of reductionism, phenomenalist and physicalist reductionism. Phenomenalism holds statements to be cognitively significant if they can be reduced to statements about one’s experience, be it outer (senses) or inner (introspection). Physicalism holds statements to be cognitively significant if they can be reduced or evidentially related to statements about physical states of affairs. Here it must be noted not only that the Vienna Circle is typically remembered in terms of the apparently phenomenalist ambitions of Carnap’s Aufbau of 1928, but also that already by the early 1930s some form of physicalism was favoured by some leading members including Carnap (1932b) and that already in the Aufbau the possibility of a different basis for a conceptual genealogy than the phenomenal one actually chosen had been indicated. Thus one must not only ask about the reductionism in the Aufbau but also consider just how reductivist in intent the physicalism was meant to be.