The positivist philosophy of science of the Vienna Circle became conflated, in the minds of their opponents, with socialist politics and economics. Neurath's radical politics repelled someone like Hayek, who credited the former's "extreme" and "naive" views on economics with his conversion from positivism. In 1935, Karl Popper published in German The Logic of Scientific Discovery, his epistemological critique of the positivist premises of the Vienna Circle. Neurath and Carnap were singled out for their defense of physicalism: the view that scientific theories are little more than a formal system of signs with their corresponding rules for application—a "practical analog" to social reality. Against their "logical empiricism," Popper proposed that theory and experience constantly modify each other through criticism to such an extent that "the empirical basis of objective science has thus nothing 'absolute' about it." Instead he famously proclaimed that science did not "rest upon solid bedrock" since "the bold structure of its theories rises, as it were, above a swamp." The falsification device favored by Popper to test the validity of theories did not convince the rest of the Vienna Circle, and Neurath remained adamant that Popper's view of science as a permanent revolution neither reflected scientific practice nor served it well.

Dieter Plehwe, Quinn Slobodian & Philip Mirowski (eds.), Nine Lives of Neoliberalism, loc. 60