Complementarity—"Instrument of Dialectical Logic"

[YoungHegelian]

Thank you 老子 for posting about Rosenfeld and Hideki, neither of whom I had heard of before. (I asked a Japanese friend who said Hideki is quite famous in Japan.) Thanks also for referencing the essay on Bohr's epistemology. I appreciated Rosenfeld's comments on Bohr's conception of complementarity—which I was surprised to see him describe elsewhere as "an instrument of dialectical logic" (p. 632):

a logical relationship between two physical phenomena, both representing aspects of a physical system equally necessary for its complete description, but corresponding to mutually exclusive experimental conditions.(p. 531)

...he continues at more length on the following page:

[T]he function of a physical theory appears itself in a new light: in view of the necessity of explicitly specifying, for each phenomenon, the conditions of its observation, the description of the phenomena is no longer, as in classical physics, a picture of events from which all reference to observation is eliminated; instead, it appears essentially as a rational and fully objective account of the interaction of the external world with human observers - a conception of science which obviously conforms much better to the part it actually plays in human society.
It is now thirty years since the clarification of the complementary features of quantum mechanics and quantum electrodynamics was essentially completed. On the face of it, physicists at large have reconciled themselves with this intrusion of dialectics into their traditional modes of thought... Too few even now realize the earnestness of the epistemological issues with which Bohr had to contend single-handed; too few fathom the depth of the problems he had solved and appreciate the revolutionary significance of his contribution to a better understanding of the dialectic process and the development of a truly scientific philosophy. (p. 532)

I like how Rosenfeld refers to it as the "dialectic process" rather than "method".
In the final paragraph, he writes:

Bohr had great expectations about the future role of complementarity. He upheld them with unshakable optimism, never discouraged by the scant response he got from our unphilosophical age... Bohr declared, with intense animation, that he saw the day when complementarity would be taught in the schools and become part of general education... We owe Bohr a tremendous widening of our scientific and philosophical horizon; he has proposed to us a view of the world of greater wealth and deeper harmony, and a conception of the function of science which makes its scope more universal and its appeal more human. (p. 535)

Bonus—in the same essay, Rosenfeld includes this delightful illustration of Bohr's "Einstein Box" thought experiment:


All page references to: Selected Papers of Léon Rosenfeld, edited by Robert S. Cohen & John J. Stachel, Springer (1978)