In short
The Vienna Circle, a group around Moritz Schlick active from 1924 to 1936, read the Tractatus as a charter for scientific philosophy: logic is tautology, metaphysics is nonsense, meaning is verification. Wittgenstein talked with Schlick and Waismann for years, but thought the Circle had misunderstood him, because for him the unsayable was what mattered most.
The Vienna Circle was a group of philosophers, scientists and mathematicians who met around Moritz Schlick (1882-1936) at the University of Vienna from 1924 until Schlick was shot dead by a former student in 1936. They wanted a scientific philosophy, free of metaphysics, and in the mid-1920s they read the Tractatus together sentence by sentence. Their 1929 manifesto, Wissenschaftliche Weltauffassung. Der Wiener Kreis, named Wittgenstein, with Einstein and Russell, as a leading representative of their outlook.
Who met Wittgenstein
Wittgenstein never attended the Circle itself. From 1927 he met a small group: Schlick, Friedrich Waismann (1896-1959) and, at first, Rudolf Carnap (1891-1970) and Herbert Feigl. Sometimes, instead of discussing philosophy, he turned his back on them and read poetry by Rabindranath Tagore. By 1929 he no longer wanted to see Carnap. His talks with Schlick and Waismann went on into the early 1930s, and Waismann's notes were published as Wittgenstein und der Wiener Kreis (1967).
What they took from the Tractatus
Three ideas above all. The truths of logic and mathematics are tautologies, so an empiricist need not explain them as knowledge of the world. Metaphysical sentences are not false but nonsensical, because they break the logic of language. And the meaning of a proposition is the method of its verification, a formula Wittgenstein himself used in conversations with Schlick and Waismann in 1929 and 1930. For the Circle it became the verification principle, a test for sorting science from metaphysics.
Why Wittgenstein felt misread
The Circle took "nonsense" as a dismissal: what cannot be verified is not worth discussing. For Wittgenstein the point of the book lay on the other side of the line, in ethics, aesthetics and the meaning of life, which can be shown but not said.
Es gibt allerdings Unaussprechliches. Dies zeigt sich, es ist das Mystische.
There is indeed the inexpressible. This shows itself; it is the mystical.
Tractatus 6.522
His friend Paul Engelmann later put it sharply: the positivists thought that what we can talk about is all that matters, while Wittgenstein believed that what really matters is what we must be silent about. The Lecture on Ethics of 1929 makes the same point from the inside.
What became of the conversation
The relationships ended badly. In 1932 Wittgenstein accused Carnap of using his ideas without acknowledgement in an article on physicalism. A book Waismann was to write setting out Wittgenstein's ideas kept stalling as those ideas changed; it appeared only after his death, in English, as The Principles of Linguistic Philosophy (1965). Meanwhile Carnap developed logical empiricism into the dominant philosophy of science of the mid-century, moving ever further from Wittgenstein's later views. See also the entry on Schlick.
Frequently asked questions
Was Wittgenstein a member of the Vienna Circle?
No. He never attended its meetings. He met a few members privately, mainly Schlick and Waismann, and the Circle treated his Tractatus as a key text, but he kept his distance and rejected the positivist reading of his work.
Did Wittgenstein believe in the verification principle?
Around 1929-1930 he did say that the sense of a proposition is the method of its verification, and Waismann recorded it. But he never used it as a weapon against metaphysics, and he soon moved on to the idea that meaning lies in use.
Sources
wittgenstein.be, “The Vienna Circle”, https://wittgenstein.be/en/philosophers/vienna-circle/ (2026-10-20)