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Realism and Neo-Kantianism in Professor Margenau's Philosophy of Quantum Mechanics

Published online by Cambridge University Press:  14 March 2022

Adolf Grünbaum*
Affiliation:
Yale University

Extract

Professor Margenau's paper presents an analysis of physical theory which has the great merit of exhibiting classical physics and modern quantum mechanics as different aspects of the same epistemological and methodological framework.

By maintaining that “there is not a tree and my construct of it, nor a wave length and my construct of it” he is denying that the constructs of ordinary common sense and, a fortiori, the theoretical constructs of the physical sciences denote entities existing independently of our rational manipulation of them. This denial then enables him to treat constructs like “tree” and “electric current” exactly on a par with the Ψ-functions of quantum mechanics not only methodologically but also ontologically. Once this is granted, he has prepared the ground for his synthesis of classical physics with quantum mechanics and is justified in inferring that “In quantum mechanics, then, the basic mode of description has remained unaltered while the rules of correspondence have undergone radical changes.”

Type
Symposium on Quantum Mechanics, II
Copyright
Copyright © Philosophy of Science Association 1950

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References

1 Philosophy of Science, Oct. 1949. (Page citations refer to this article.)

2 p. 294.

3 p. 300.

4 p. 287.

5 Mr. Margenau is careful to point out on p. 292 that his constructs are not merely the product of an integration of sensed qualities. Therefore, they should not be identified with Russell's “logical constructions” as to pedigree of meaning but only as to lack of ontological status or denotation.

6 We shall see that it is very difficult to give a satisfactory analysis of the meaning of “reconstruction”.

7 p. 287.

8 In the present context, I understand by the “branches” of physics not the customary five divisions but the disciplines of classical physics, relativity, and quantum mechanics.

9 p. 288.

10 The writer frankly concedes that the term “interaction” hides a great many lacunae in the realist theory.

11 See p. 289.

12 p. 292, passim.

13 p. 293.

14 See Paul Weiss, Nature and Man, New York, 1947, p. 23.

15 Objections raised on this point by the extreme operationist cannot be entered upon here, and would, in any case, not be offered by Mr. Margenau.

16 It is interesting to note that Carnap in “Testability and Meaning” (This journal, vols. 3, 1936, and 4, 1937) fails to explain why scientists are ever extending the empirical domain of application of previous constructs. Carnap treats this fact merely as a fact in the linguistic behavior of scientists and therefore solely as a matter of convention. His partial conditional definitions of constructs are made partial by him merely in order to reconstruct the language of science.

The realist holds that when scientists speak of the flow of an electric current, for instance, in connection with such diverse observable situations as magnetic needle deflections and silver precipitations, they do not do so primarily for reasons of linguistic convenience. Their linguistic usage merely expresses the hypothesis that these diverse empirical even-tuations are evidence for the presence in each case of real electrons in motion relative to the observer.

17 p. 295.

18 Einstein's most recent statement of his views can be found in Dialectica, vol. 2, No. 3/4, 1949.

19 Although Kant's terminological inconsistencies are proverbial, it is true that, on the whole, his uses are as follows: the term “transcendental” designates those factors which are posited (however vaguely) as a result of his application of the presuppositional method to theoretic or ethical knowledge; the term “transcendent” refers to the ontological realm with the intent of conveying an illicit use of theoretic reason.

20 Cf. Moritz Schlick, Problems of Ethics, Chapter VII and Philipp Frank, Das Kausalgesetz und seine Grenzen, pp. 148–155.