Logical Positivism and the Later Wittgenstein

During the 1920s and 1930s, a group of philosophers, scientists, and mathematicians gathered in Vienna around Moritz Schlick to form the Vienna Circle, the movement that came to be known as logical positivism or logical empiricism. Members such as Rudolf Carnap, Otto Neurath, and Friedrich Waismann sought to combine the new formal logic of Frege and Russell with a rigorously empiricist theory of meaning, taking early inspiration from Wittgenstein's Tractatus, whose author they read closely, though he never joined the group himself. Their central doctrine was the verification principle: a statement is cognitively meaningful only if it is either analytically true or false in virtue of its logical form, or empirically verifiable, at least in principle, through observation. On this criterion, the propositions of traditional metaphysics, theology, and much of ethics and aesthetics were judged to be neither true nor false but strictly meaningless, mere pseudo-statements masquerading as factual claims. The British philosopher A. J. Ayer popularized these ideas for an English-speaking audience in Language, Truth and Logic (1936), a short, polemical book that became the most widely read statement of logical positivism, even as the movement's own members increasingly struggled to formulate the verification principle in a way that did not undermine itself or exclude parts of science.