Logical positivism

Logical positivism and logical empiricism, which together formed neopositivism, was a movement in Western philosophy that sought to legitimize philosophical discourse by placing it on a basis shared with empirical sciences' best examples, such as Einstein's general theory of relativity. Its central thesis was verificationism, a theory of knowledge which asserted that only statements verifiable through empirical observation are 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—groups of philosophers, scientists, and mathematicians in Berlin and in Vienna—propounded logical positivism starting in the late 1920s.

Logical positivists culled from Ludwig Wittgenstein's early philosophy of language the verifiability principle or criterion of meaningfulness. As in Ernst Mach's phenomenalism, whereby the mind can know only actual or potential sensory experience, verificationists took all sciences' basic content to be only sensory experience. And some influence came from Percy Bridgman's musings that others proclaimed as operationalism, whereby a physical theory is understood by what laboratory procedures scientists perform to test its predictions. In verificationism, only the verifiable was scientific, and thus meaningful (or cognitively meaningful), whereas the unverifiable, being unscientific, was meaningless "pseudostatements" (just emotively meaningful). Unscientific discourse, as in ethics and metaphysics, would be unfit for discourse by philosophers, newly tasked to organize knowledge, not develop new knowledge.

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