Bertrand Russell hand-copied pages of Principia so Rudolf Carnap could read them
A young German student could not afford Principia Mathematica, and neither could his university. So he wrote to Bertrand Russell, who replied by copying out long passages by hand. That student, Rudolf Carnap, became a leading voice of the Vienna Circle and of the movement called logical positivism.
Carnap was born on 18 May 1891 in Ronsdorf, now part of Wuppertal, to a father who had climbed from poor ribbon-weaver to factory owner. His uncle was the archaeologist Wilhelm Dorpfeld, whom he joined on a dig in Greece at ten. At 14 he taught himself Esperanto, attending its world congress in Dresden in 1908; at the 1924 Vienna congress he first met Otto Neurath. Raised in a devout Protestant home, he later became an atheist.
At Jena he was among very few students attending Gottlob Frege's lectures on mathematical logic, which led him to Russell. Though morally opposed to the First World War, he served three years in the army before studying physics in Berlin, where Einstein had just arrived. His first doctoral thesis, on an axiomatic theory of space and time, was rejected by the physics department as too philosophical while the philosophy professor called it pure physics, so he wrote a more conventional Kantian version in 1921.
In 1926 Moritz Schlick brought him to Vienna. There Carnap joined the circle of thinkers around Schlick, Hans Hahn and Neurath, occasionally visited by Kurt Godel, co-wrote its 1929 manifesto and helped launch the journal Erkenntnis. His Logical Structure of the World, published in 1928, set out to organise every scientific statement into a single logical hierarchy, and it became a landmark of epistemology.
Socialist and pacifist views made Nazi Germany dangerous for him, so in 1935 he left for the United States. Schlick was murdered in Vienna the next year. Carnap taught at Chicago from 1936 to 1952, writing on semantics, modal logic and probability, spent time at Princeton's Institute for Advanced Study, and moved to UCLA in 1954 after refusing a Berkeley post that required a loyalty oath. W. V. Quine, whom he met in Prague in 1933, argued with him for decades and respected him throughout. Carnap died on 14 September 1970.
Source: Rudolf Carnap
