Perspectives on Science

Do the terms “logical positivism” and “logical empiricism” mark a philosophically real and significant distinction? There is, of course, no doubt that the first term designates the group of philosophers known as the Vienna Circle, headed by Moritz Schlick and including Rudolf Carnap, Herbert Feigl, Philipp Frank, Hans Hahn, Otto Neurath, Friedrich Waismann and others. What is debatable, however, is whether the name “logical positivism” correctly distinguishes their doctrines from related ones called “logical empiricism” that emerged from the Berlin Society for Scientific Philosophy around Hans Reichenbach which included Walter Dubislav, Kurt Grelling, Kurt Lewin and a young Carl Gustav Hempel.¹

The person who called the co-referentiality of the two terms into question was Reichenbach himself. He did so in two publications of the second half of the 1930s—in an article in Journal of Philosophy (1936) and in his Experience and Prediction (1938)—in order to alert readers to important differences between his own philosophy and that of the Vienna Circle.² Reichenbach’s distinction was taken up by his former student Wesley Salmon.³ Not only did Salmon restate it, but he also asserted, categorically and very much in Reichenbach’s spirit, that “our chief inheritance from logical positivism” is “logical empiricism” ([1985] 2005, p. 7). The story of this inheritance is the story of “twentieth-century scientific philosophy”: [End Page 58]

This movement grew chiefly out of the logical positivism of the Vienna Circle (with which Carnap was mainly associated) and the logical empiricism of the Berlin Group (with which Hans Reichenbach was connected). By midcentury virtually every important figure in the movement had relinquished some of the more extreme views of early logical positivism, abandoned the designation of ‘logical positivist’, and adopted ‘logical empiricism’ as the name of their movement. After that, logical positivism no longer existed.

([1994] 2005, p. 19)

Who then “killed” logical positivism—on this story?⁴ In print Salmon himself went no further than to state that Reichenbach regarded his 1938 book as “his refutation of logical positivism” ([1994] 2005, p. 21; cf. [1985] 2005, p. 7) but he also gave no sign of dissent.⁵ There is, to be sure, this difference between the historical constructions of Reichenbach and Salmon: given his longer-term perspective Salmon allowed Carnap to become a logical empiricist, whereas Reichenbach was unable to report such redemption. Yet Reichenbach, as logical empiricism personified, remained central on his sketch of the development of analytic philosophy of science.

Now there are, of course, many ways of telling a story of development and it is not my business here to deny the importance of Reichenbach either as a philosopher in his own right or as a moving force of twentieth-century scientific philosophy.⁶ What I do want to call into question, however, is the reliability of this Reichenbachian account as far as the Vienna Circle is concerned. There are different ways in which this can be done. One can point out that the development of Vienna Circle philosophers away from what Reichenbach designated as the doctrines and preoccupations of logical positivism was to a very large extent an internal matter prompted by internal opposition.⁷ One can point out that Carnap’s thought in particular underwent a development far beyond the embrace of [End Page 59] the probabilistic realism that Reichenbach championed and so effected a radical reorientation of the office even of scientific philosophy.⁸ On either of these arguments the Vienna Circle regains the doctrinal multidimensionality that the Reichenbachian account denies it.

Here I shall pursue my objective differently, however, by engaging directly with the history of the appellations which encapsulate Salmon’s Reichenbachian account.⁹ I shall review the use that leading members and early onlookers of the movement(s) made of the terms in question (and closely related ones), both in terms of self- and third person-ascriptions, to see whether the usage championed by Reichenbach reflects a distinction recognized by the philosophers involved themselves. It might be wondered whether this is a proper deployment of scholarly effort. Aren’t names but “smoke and mirrors”—or “Schall und Rauch” as a...