Logical positivism and logical empiricism, which together formed neopositivism, was a movement in Western philosophy that embraced verificationism, an approach that sought to legitimize philosophical discourse on a basis shared with the best examples of empirical sciences. In this theory of knowledge, only statements verifiable either logically or empirically would be cognitively meaningful. Efforts to convert philosophy to this new scientific philosophy were intended to prevent confusion rooted in unclear language and unverifiable claims. The Berlin Circle and the Vienna Circle propounded logical positivism starting in the late 1920s.