Leon Rosenfeld

There is much more to Leon Rosenfeld than his relationship to Niels Bohr — see (Jacobsen 2007, 2012). But here we focus on that relationship. After Bohr’s death, Rosenfeld decided to become the defender of his ideas and his reputation. However, a strong case can be made that Rosenfeld is responsible for many miconstruals of Bohr’s point of view.

One important fact to keep in mind is that Rosenfeld was a Marxist, and his Marxist historiography influenced his understanding of what was going on in the physics of his day. (Much of the “inevitability” talk about the quantum revolution comes from Rosenfeld rather than from Bohr.) What’s more, Rosenfeld had little interest in and tolerance for “non-scientific” philosophy. That might partially explain why Rosenfeld wrote such a negative review of Max Jammer’s book The Conceptual Development of Quantum Mechanics. Whereas Jammer suggests some (indirect) influence of Kierkegaard on Bohr, Rosenfeld states that:

A much more serious objection must be levelled against the author’s handling of the epistemological questions. Misled by superficial coincidences, he imagines that Bohr’s thought has been influenced, through Høffding, by Kierkegaard and William James. There can be no doubt that his surmise is unfounded. Bohr was a completely independent thinker; from early youth, he developed his epistemological ideas single-handed and with no more philosophical preparation than Høffding’s elementary course of lectures. What the latter, and still more his father, encouraged in him was an attitude of open-mindedness and unprejudiced approach to the problems, and certainly not any reliance on particular philosophical systems. There was indeed one person who did exert a real influence on Bohr’s views: this was his brother Harald. Niels Bohr told me once how much he owed to Harald for the clarification of his ideas about the function of mathematics, which were of great moment in the early formation of his more general conception of the role of language. If anything, Harald strongly dissuaded Niels from taking any interest in Kierkegaard. As to Williams James, it was only after the completion of Bohr’s epistemological analysis of quantum mechanics that his attention was called to the Principles of Psychology: the similarity of attitudes interested Bohr, but did not influence him.

Rosenfeld also seems to be responsible for the icy reception that Everett received in Copenhagen in 1956. Rosenfeld later said that Everett was “undescribably (sic) stupid” and “could not understand the simplest things in quantum mechanics”.¹ Bohr never spoke like that about anybody.