Logical positivism

5. Emigration, influence, aftermath

The rise of the Nazi regime set off a wholesale migration of logical positivists to the English-speaking world. Carnap, who had become professor at Prague in 1931, moved in 1936 to the University of Chicago. Reichenbach, who had fled to Istanbul in 1933, moved in 1938 to the University of California at Los Angeles. (After Reichenbach’s death in 1953 Carnap took over his position at UCLA, beginning in 1954.) Neurath, after leaving Vienna for The Hague in 1934, fled to England in 1940 – where he worked in Oxford until his death in 1945. Friedrich Waismann fled for England as well, where he lectured at Oxford from 1939. Philip Frank emigrated to the USA (also from Prague) in 1938 and settled at Harvard in 1939. Karl Menger took up a position at Notre Dame in 1937, and Kurt Gödel became a member of the Institute for Advanced Study at Princeton in 1940. Herbert Feigl went first to the University of Iowa in 1933 and then to the University of Minnesota in 1940, where he founded the influential Minnesota Center for the Philosophy of Science in 1953. Carl Hempel joined Carnap at the University of Chicago in 1939 and, after teaching at Queens College and Yale, settled at Princeton in 1955. (Schlick was murdered by a deranged student at the University of Vienna in 1936.)

The growth of philosophy of science in the USA was decisively shaped by the work of Carnap, Reichenbach and Hempel. Reichenbach influenced especially the development of philosophy of physics through his work on geometry, relativity and the direction of time (see Relativity theory, philosophical significance of §3). Hempel published extraordinarily influential papers on the logical analysis of explanation and confirmation and thereby furthered the ideal of scientific philosophy first articulated by Carnap (see Explanation; Confirmation theory). Carnap himself continued the construction of formal languages in which such concepts as testability, modality and probability could be rationally reconstructed or ‘explicated’ and thus contributed further to the same ideal. Indeed, Carnap’s explication of concepts through the construction of formal languages influenced the English-speaking world of analytic philosophy far beyond the borders of philosophy of science. Developments in formal semantics and philosophy of language, in particular, rested on Carnap’s initial work on modality (see Semantics §2).

The Carnapian ideal of explication is based on a sharp distinction between logical and empirical investigation, analytic and synthetic truth. In his Logical Syntax of Language (1934) Carnap had attempted a general explication of the concept of analyticity itself – a general formal method for distinguishing, within the context of any given formal language, the analytic from the synthetic sentences of that language. After accepting Alfred Tarski’s semantical conception of truth in 1935, however, Carnap abandoned the approach of Logical Syntax and frankly admitted that (although explications for various particular languages could still be constructed) he now had no generally applicable explication of the concept of analyticity. After studying with Carnap in the early 1930s, W.V. Quine then exploited this situation to attack the concept of analyticity as such and, on this basis, to attack the Carnapian ideal of logical explication as well (see Quine, W.V. §§2, 4). Philosophy, for Quine, is itself a kind of empirical science – a branch of human psychology or ‘naturalized epistemology’ (see Naturalized epistemology). Moreover, at the same time that Quine was articulating this new philosophical vision, Thomas Kuhn published The Structure of Scientific Revolutions (1962) in the International Encyclopedia of Unified Science edited by Carnap and Charles Morris. Whereas Carnap had relegated the (conventional) choice of scientific language to the limbo of pragmatics, Kuhn concentrated on those factors – especially social factors – which, in a scientific revolution, determine precisely this kind of choice. These ideas, in harmony with Quine’s more general naturalistic point of view, then led to historical and sociological approaches to the study of science and thus, in the end, to the decline of logical analyses of scientific language in the Carnapian style.