Willard Van Orman Quine (1908–2000) spent the 1932–33 academic year in Vienna, Prague, and Warsaw; he attended Carnap's lectures and went to Schlick's seminars. He returned home to Harvard as the brightest American envoy of logical positivism. But during the 1940s, as he kept working on Carnap's sharp distinction between 'analytic' propositions (true by meaning alone) and 'synthetic' ones (verified by experience), he came to suspect that the distinction rested on a closed circle: 'analytic' was defined via 'synonymy,' synonymy via 'definition,' and definition once again via 'analyticity.'

In January 1951 his article 'Two Dogmas of Empiricism' in The Philosophical Review turned this suspicion into an attack. Quine names two dogmas. The first is the analytic–synthetic distinction that runs from Kant to the Vienna Circle. The second is reductionism: the belief that every meaningful proposition can be translated into single statements about experience. Quine argues that neither dogma can be defended. In their place he develops a thesis taken from Pierre Duhem: science is not a list of individual hypotheses but a 'web of belief.' Experience presses on the edges of the web; whether to preserve or revise some proposition inside the web — even one in mathematics — is always a choice. 'The unit of empirical significance is the whole of science.'

The consequences are far-reaching. If no single proposition can be verified in isolation, then the Vienna Circle's verdict that 'metaphysics is meaningless' loses its grounds, and the boundary between science and metaphysics becomes gradual rather than sharp. If even logic and mathematics are in principle revisable theoretical statements, then philosophy no longer enjoys a privileged position above science. Quine extends this line in his 1960 Word and Object: the indeterminacy of translation (in radical interpretation, the meaning of a sentence can never be fixed in only one way) and then the programme of 'naturalised epistemology' — the theory of knowledge is itself a chapter of cognitive science.

The article is the signature of analytic philosophy's change of course. Carnap kept arguing against the 'two dogmas' until his death, but the field shifted rapidly towards Quine. Davidson's radical interpretation, Kripke's modal logic and theory of naming, Putnam's internal realism, and Rorty's pragmatist turn all developed on the ground Quine opened. It is the moment when the logical positivism imported from continental Europe is fully Americanised, fused with the pragmatist tradition, and turned into an analytic philosophy that looks rigorous on the outside but is soft at the core.