Thomas Ryckman is Professor of Philosophy at Stanford University, and author of The Reign of Relativity: Philosophy in Physics 1915-1925, Oxford University Press, 2005.
Einstein developed some of the most ground breaking theories in physics. So why have you written a book that examines him as a philosopher?
Einstein’s theoretical accomplishments, especially the two theories of relativity, as well as his occasional philosophical pronouncements, had a tremendous impact in shaping the modern discipline of philosophy of science in the first half of the 20th century. Also, throughout his career as a theoretical physicist, Einstein in fact adhered to a particular style of philosophizing, though not in a sense familiar to academic departments of philosophy. I call this a “philosophy of principles”; his central innovations came by elevating certain physical, formal and even metaphysical principles to the status of postulates, and then exploring the empirical consequences.
Einstein was famous for his pacifist views yet set them aside to contribute towards the development of the atomic bomb. This was something he later regretted, campaigning for nuclear disarmament alongside Bertrand Russell. What spurred his, albeit temporary, interest in the development of atomic weapons?
Though this important matter is but briefly mentioned in the book, which is entirely devoted to identifying and explaining the philosophy guiding Einstein’s practice as a theoretical physicist, Einstein reluctantly surrendered his pacifist views with the advent of Hitler to power as Chancellor Germany in early 1933. After two German physical chemists discovered, inadvertently, atomic fission in 1938, it quickly became clear to nuclear physicists that an atomic weapon was possible. Given that so many prominent quantum theoreticians were German, there was an understandable fear that if such a weapon could be made, German expertise would pull it off. Of course, if Hitler had an atomic weapon, it would have been a disaster for any countries resisting German aggression. So Einstein, in the summer of 1939, signed the famous letter to Roosevelt, warning of this possibility and urging the United States to engage in an accelerated program of research on the possibility of atomic weapons. It is true, however, that Einstein had nothing further to do with atomic weapons research, and that in 1945 he lamented the use of atomic weapons against Japan, famously stating that he would never have sent the letter if he had known that the bomb would not be used against Hitler but against civilian populations.
There have been many books written about Einstein. What makes this one different?
Much has been written over the years attempting to assimilate Einstein’s philosophical views to one or another philosophical position or school, despite his explicit resistance to such assimilation. I think it is fair to say, however, that in the truly enormous literature on Einstein, there is no other work that attempts to excavate Einstein’s philosophy from his practice as a theoretical physicist.
What do you see as his most important contribution to the philosophy of science?
In my opinion, Einstein demonstrates that it is possible to be a “realist” about science without adopting the metaphysical presuppositions of what is today called “scientific realism”. In particular, Einstein balanced the aspirational or motivational realist attitude of many working scientists with the clear recognition that realism remains a metaphysical hypothesis, not demonstrable by empirical evidence.
How did your own interest in Einstein develop?
As a philosopher of physics, it is difficult to altogether avoid Einstein. But doing a book like this was really only made possible once the first ten or twelve volumes of Einstein’s Collected Papers had appeared by around 2005. Besides his published papers and working notebooks, these volumes contain much of his correspondence with other physicists, philosophers and friends, and so present a more revealing side of Einstein.
How do you think Einstein’s work will continue to influence philosophy of science in the future?
Besides the point above about realism, Einstein personifies the traditional quest to comprehend Nature from a unified point of view according to the gold standard of explanation, the principle of sufficient reason: that everything that happens has a reason why it happens as it does, and not otherwise. His example is particularly timely today since, following developments in string theory and inflationary cosmology, the tendency of current proposals in foundational theory is to explain fundamental features of known physics by appeal to anthropic reasoning, essentially arguing that if these features were slightly different than they are observed to be, we should not be here to observe them at all.