Short answers, pulled from the story.
Rudolf Carnap was a German-American philosopher born on the 18th of May 1891 in Ronsdorf, in present-day Wuppertal, Germany. He was a major member of the Vienna Circle and a leading advocate of logical positivism, the view that meaningful statements must be verifiable by experience. He died on the 14th of September 1970.
Carnap joined the Vienna Circle in 1926 after accepting a position offered by Moritz Schlick at the University of Vienna. He co-wrote the Circle's 1929 manifesto alongside Hans Hahn and Otto Neurath, and co-founded the philosophy journal Erkenntnis with Hans Reichenbach.
Der logische Aufbau der Welt, published in 1928 and translated as The Logical Structure of the World in 1967, argues that all scientific concepts can be organized into a single logical hierarchy grounded in basic perceptual experience. Carnap called this project "constitution theory" and used symbolic logic to show how concepts reduce to more fundamental ones.
The principle of tolerance, introduced in Logische Syntax der Sprache in 1934, holds that there is no single correct logical language. Every logical language is acceptable provided it is supported by exact definitions, and the choice of language should be guided by practical considerations such as consistency, simplicity, and usefulness for a given purpose.
Carnap applied the verifiability principle: a sentence is meaningful only if there is a way to establish whether it is true or false by specifying empirical conditions. Metaphysical concepts such as "god", "soul", and "the absolute" cannot be traced to direct observation or verified in any way, so the sentences containing them carry no factual content and are meaningless by this standard.
The majority of Carnap's papers were purchased by the University of Pittsburgh in 1974 from his daughter, Hanna Carnap-Thost. The collection includes thousands of letters, diaries, notes, and over a thousand pages of lecture outlines. The University of California also maintains a collection, and microfilm copies are held by the Philosophical Archives at the University of Konstanz in Germany.