Carl Gustav Hempel
To explain something scientifically is to show that it follows from general laws together with the particular circumstances.
Placement
Logical empiricist from the Berlin Group: to explain an event is to derive it from general laws and initial conditions (deductive-nomological model); the raven paradox shows how puzzling confirmation is.
Key ideas
- Deductive-nomological explanation
- Raven paradox
- Critique of the verifiability criterion
Teachers: Rudolf Carnap, Hans Reichenbach
Students: Robert Nozick
Influence
Influenced by 3
Rudolf Carnap studied with
studied with
Hempel studied with Carnap, Schlick and Waismann in Vienna in the autumn semester of 1929 and in 1937–38 worked with Carnap at the University of Chicago; his doctorate (Berlin, 1934) was taken elsewhere. SEP “Carl Hempel”
Evidence: AI draft
Rudolf Carnap › 1891–1970
Hans Reichenbach studied with
studied with
Hempel studied with Reichenbach in Berlin from 1929, went to Vienna that autumn at his suggestion and belonged to his Berlin Group; after Reichenbach’s emigration his doctorate on probability (1934) was examined by Wolfgang Köhler and Nicolai Hartmann. SEP “Carl Hempel”
Evidence: also in InPhO · InPhO
Hans Reichenbach › 1891–1953
Janina Hosiasson-Lindenbaum
influenced by
Hempel discussed Hosiasson-Lindenbaum’s probabilistic answer to the raven paradox, on which a non-black non-raven confirms only to a tiny degree (‘Studies in the Logic of Confirmation’, 1945). C. G. Hempel, “Studies in the Logic of Confirmation”, Mind 54 (1945); J. Hosiasson-Lindenbaum, “On Confirmation”, Journal of Symbolic Logic 5 (1940); SEP “Confirmation”
Evidence: AI draft
Janina Hosiasson-Lindenbaum › 1899–1942
Influenced 1
Robert Nozick taught
taught
Nozick wrote his Princeton dissertation, The Normative Theory of Individual Choice (1963), under Hempel’s supervision; it was printed in 1990. R. Nozick, The Normative Theory of Individual Choice (diss. Princeton 1963; printed 1990)
Evidence: also in InPhO · InPhO
Robert Nozick › 1938–2002
Criticism
Criticizes 1
A. J. Ayer
criticised
Hempel argued that Ayer’s verifiability criterion, even as revised in 1946, either admits metaphysics or excludes scientific laws (‘Problems and Changes in the Empiricist Criterion of Meaning’, 1950). C. G. Hempel, “Problems and Changes in the Empiricist Criterion of Meaning”, Revue Internationale de Philosophie 11 (1950), 41–63; A. Church, review of Ayer, Journal of Symbolic Logic 14 (1949)
Evidence: AI draft
A. J. Ayer › 1910–1989
Works
If every black raven confirms “all ravens are black”, then so does every non-black thing that is not a raven – a white shoe, as later retellings put it: the paradox of confirmation.
Written with the chemist Paul Oppenheim, the paper sets out the deductive-nomological model: an explanation derives what is to be explained from laws and initial conditions.
Position
Hempel gave logical empiricism its classical accounts of confirmation and explanation, and was at the same time one of its sharpest internal critics. “Studies in the Logic of Confirmation” (1945) showed a paradox: if every black raven confirms “all ravens are black”, and this law is logically equivalent to “everything non-black is a non-raven”, then a white shoe confirms it too. With Oppenheim he set out the deductive-nomological model in 1948: an explanation is an argument whose premises contain at least one general law and particular conditions, and whose conclusion describes what is to be explained. He had already applied the model to history in 1942, and later added inductive-statistical explanations for probabilistic laws. Explanation and prediction have the same logical form. In “Problems and Changes in the Empiricist Criterion of Meaning” (1950) he showed that every proposed formulation of the verifiability criterion, including Ayer’s, either excludes scientific laws or lets in metaphysics, and concluded that cognitive significance comes in degrees. In his late papers he engaged closely with Kuhn, his colleague at Princeton, and moved towards a more pragmatic view of scientific rationality.
Life & context
Carl Gustav Hempel was born in Oranienburg near Berlin in 1905. He studied mathematics, physics and philosophy in Göttingen, Heidelberg and Berlin, spent 1929–30 in Vienna, where he met Carnap, Schlick and Waismann, and belonged to Hans Reichenbach’s Berlin Group. His doctorate on probability (1934) was completed after Reichenbach had been dismissed. Because his wife was of Jewish descent he left Germany for Belgium, where he worked with Paul Oppenheim, and in 1937 went to Chicago as Carnap’s assistant. He taught at City College in New York, at Yale (1948–1955), at Princeton (1955–1973), where Robert Nozick was among his doctoral students, and finally at Pittsburgh. He died near Princeton in 1997.
Further main works
- The Function of General Laws in History (1942)
- Problems and Changes in the Empiricist Criterion of Meaning (1950)
- Aspects of Scientific Explanation (1965)
- Philosophy of Natural Science (1966)
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