Moritz Schlick gathered the Vienna Circle on Thursday nights in a chemistry building
A physicist trained under Max Planck, Moritz Schlick came to distrust any claim that could be neither defined nor tested. In Vienna he hosted weekly meetings that drew Kurt Gödel, Rudolf Carnap and Otto Neurath, coaxed Wittgenstein back toward philosophy, and founded the movement known as logical positivism.
Schlick was born in Berlin on 14 April 1882 into a wealthy, conservative Prussian family. As a teenager he read Descartes and Schopenhauer and was especially struck by Nietzsche's Zarathustra, yet he chose physics, believing only mathematical physics yielded exact knowledge. His 1904 doctorate under Planck in Berlin dealt with how light reflects in a medium that is not uniform. He then drifted to philosophy, and in 1908 wrote a short book on eudaemonism, the idea that happiness comes from personal fulfilment rather than fleeting pleasure.
He was among the first philosophers to take relativity seriously, writing on Einstein's special theory in 1915, when it was barely a decade old. His Space and Time in Contemporary Physics used Poincaré's conventionalism to explain why Einstein adopted a non-Euclidean geometry, and Einstein wrote that no philosopher had treated the subject with comparable clarity. In 1922 Schlick took the Vienna chair once held by Boltzmann and Mach. The discussion group he was invited to lead, first called the Ernst Mach Association, became the Vienna Circle.
Its shared principle came from his General Theory of Knowledge, worked on between 1918 and 1925: only definitional truths, as in logic and mathematics, are self-evident, and every other statement must answer to experience. A claim that is neither is metaphysical, meaning nonsense. He called the free will debate a pseudo-problem, arguing that philosophers confused laws of nature, which describe, with laws of the state, which compel. His Problems of Ethics surprised colleagues by treating ethics as legitimate philosophy.
As Nazism rose, many Circle members emigrated, but Schlick stayed. On 22 June 1936 a former student, Johann Nelböck, shot him dead on the university's main stairway. Propagandists turned the killing into a nationalist and anti-Jewish cause, though Schlick was not Jewish, and after the 1938 annexation Nelböck was released having served two years of a 10-year sentence.
Source: Moritz Schlick
