It was the historian Max Jammer who first claimed a connection between Kierkegaard and Bohr.
There can be no doubt that the Danish precursor of modern existentialism and neoorthodox theology, Søren Kierkegaard, through his influence on Bohr, affected also the course of modern physics to some extent. This can be gathered not only from certain references and allusions in Bohr’s philosophically oriented writings but also from the very fact that Harald Høffding, an ardent student and brilliant expounder of Kierkegaard’s teachings, was the principal authority on philosophical matters for the young Bohr. We know that Bohr attended Høffding’s lectures at the University of Copenhagen and read Høffding’s writings in which Kierkegaard’s philosophy occupied a prominent place. Furthermore, Høffding and Niels’s father, Christian Bohr, a professor of physiology at the University of Copenhagen, were not only colleagues but also intimate friends who had much in common; Christian Bohr’s anti-Haeckelism and Harald Høffding’s anti-Hegelianism placed both of them in opposition to contemporary thought. Kierkegaard’s philosophy of life and religion, his so-called “qualitative dialectic,” his antithesis between thought and reality, his contradictory conceptions of life, and his insistence on the necessity of choice had apparently left a deep impression on Bohr’s youthful mind. In particular Kierkegaard’s emphasis on the practical value of thought, his opposition to the construction of systems, and his insistence that thought could never attain reality, for as soon as it thought to have done so it falsified reality by having changed it into imagined reality—all these ideas contributed to the creation of a philosophical climate which facilitated the surrender of classical conceptions. Of particular importance for Niels Bohr was Kierkegaard’s idea, repeatedly elaborated by Høffding, that the traditional speculative philosophy, in its claim to being capable of explaining everything, forgot that the originator of the system, however unimportant he may be, forms part of the being which is to be explained. “A system can be conceived only if one could look back on completed existence—but this would presuppose that one no longer exists. Man cannot without falsification conceive of himself as an impartial spectator or impersonal observer; he always necessarily remains a participant. Thus man’s delimitation between the objective and the subjective is always an arbitrary act and man’s life a series of decisions. Science is a determinate activity and truth a human product, not only because it is man who created knowledge, but because the very object of knowledge is far from being a thing ready-made from all eternity. (Jammer 1966)
In his review of Jammer’s book, Leon Rosenfeld scoffed at these claims:
Misled by superficial coincidences, [Jammer] 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. The author could have inferred all this (or most of it) from published statements; but he somehow went astray and ponderously built in a completely fictitious “Kierkegaard-Høffding” ideology into the discussion of Bohr’s work. This unfortunate error runs through the whole book and spoils the argument wherever it intrudes into it. (Rosenfeld 1969)
Why would Jammer even have suspected that there might be some connection between Kierkegaard and Bohr? Even without knowing any specific details, Kierkegaard and Bohr both lived in Copenhagen — a small city — just a few decades apart. And Kierkegaard was a highly influential, albeit controversial, figure. The simple fact is that Kierkegaard “influenced” every intellectual who grew up in Copenhagen at the end of the nineteenth century.
We will come back to Jammer’s claims, but it’s important to point out first that Rosenfeld’s repudiation of those claims left an indelible mark on Bohr’s foremost defender, David Favrholdt, who went out of his way to insist — on every possible occasion — that there was no influence of Kierkegaard on Bohr.
Kierkegaard, unlike Grundtvig, was no despiser of science. In a discussion of a book on physiology by Carl Gustav Carus, Kierkegaard accepted the significance and legitimacy of science. (John Elrod, Kierkegaard and Christendom)
(Rosfort 2013) (Halvorson 2023)
It might seem that Kierkegaard wasn’t interested in metaphysics or logic — as analytic philosophers understand these terms. But that would be a mistake. In fact, Kierkegaard believes that bad views about these subjects lead to confused views about one’s self and one’s task in life.
“I don’t have a system, but I do have a worldview”
Den første betragtingsmåde ser mennesket udefra, som objekt, – den anden betragtningsmåde ser mennesket indefra, oplever det som subjekt. Det ‘hele’ menneske kan ikke gøres til genstand for udvendig betragtning, det kan kun opleves indefra. (Villy Sørensen, Introduction to The Concept of Anxiety)
Harald Bohr sent Niels a copy of Kierkegaard’s Stages on Life’s Way. Bohr reports, in a letter to Harald, that he likes the book, but that he disagrees with Kierkegaard on several points. As far as we know, this is the only reference that Bohr ever made to Kierkegaard in his written works.
It would be more intriguing if we knew that Niels Bohr had read Kierkegaard’s Concluding Unscientific Postscript, since that is the book in which Kierkegaard argues most directly against the Hegelian view of the goals of Wissenschaft. But we have no evidence, not even indirect, that Bohr read this book.
Harald Høffding had read and absorbed all of Kierkegaard’s works. Høffding was also shaped directly by Rasmus Nielsen — whose epistemology and philosophy of science was Kierkegaard-inspired — as well as by Hans Brøchner.
Here are some passages from Kierkegaard’s Postscript