Carl Gustav Hempel

Carl Gustav "Peter" Hempel (January 8, 1905 – November 9, 1997) was a German writer and philosopher. He was a major figure in logical empiricism, a 20th-century movement in the philosophy of science. He is especially well known for his articulation of the deductive-nomological model of scientific explanation, which was considered the "standard model" of scientific explanation during the 1950s and 1960s. He is also known for the raven paradox (also known as "Hempel's paradox").

Hempel studied mathematics, physics and philosophy at the University of Göttingen and subsequently at the University of Berlin and the Heidelberg University. In Göttingen, he encountered David Hilbert and was impressed by his program attempting to base all mathematics on solid logical foundations derived from a limited number of axioms.

After moving to Berlin, Hempel participated in a congress on scientific philosophy in 1929 where he met Rudolf Carnap and became involved in the Berlin Circle of philosophers associated with the Vienna Circle. In 1934, he received his doctoral degree from the University of Berlin with a dissertation on probability theory.

Within a year of completing his doctorate, the increasingly repressive and anti-semitic Nazi regime in Germany had prompted Hempel to emigrate – his wife was of Jewish ancestry – to Belgium. In this, he was aided by the scientist Paul Oppenheim, with whom he co-authored the book Der Typusbegriff im Lichte der neuen Logik on typology and logic in 1936. In 1937, Hempel emigrated to the United States, where he accepted a position as Carnap's assistant at the University of Chicago. He later held positions at the City College of New York (1939–1948), Yale University (1948–1955) and Princeton University, where he taught alongside Thomas Kuhn and remained until made emeritus in 1973. Between 1974 and 1976, he was an emeritus at the Hebrew University in Jerusalem before becoming University Professor of Philosophy at the University of Pittsburgh in 1977 and teaching there until 1985.

Hempel never embraced the term "logical positivism" as an accurate description of the Vienna Circle and Berlin Group, preferring to describe those philosophers – and himself – as "logical empiricists". He believed that the term "positivism", with its roots in Auguste Comte, invoked a materialist metaphysics that empiricists need not embrace. He regarded Ludwig Wittgenstein as a philosopher with a genius for stating philosophical insights in striking and memorable language, but believed that he (or, at least, the Wittgenstein of the Tractatus) made claims that could only be supported by recourse to metaphysics. To Hempel, metaphysics involved claims to know things which were not knowable; that is, metaphysical hypotheses were incapable of confirmation or disconfirmation by evidence.

In 2005, the City of Oranienburg, Hempel's birthplace, renamed one of its streets "Carl-Gustav-Hempel-Straße" in his memory.