The Synthetic A Priori in the 20th Century
Neo-Kantians facing the quantum and relativistic revolutions
General relativity and quantum mechanics, as they were developed in between 1900 and 1930, appeared at first glance to refute claims that Kant thought we knew “a priori,” without appeal to details of experience.
Quantum mechanics appeared to challenge (more plausibly than the challenge to logic) Kant’s claim in his “second analogy of experience” that deterministic causal interaction lay at the foundation of physical explanation. Grete Hermann refuted John von Neumann’s attempted proof of this challenge, arguing that quantum mechanics did not show that physics had the potential to leave causation behind.
Einstein’s general relativity appeared to refute Kant’s “axioms of intuition,” which stated that Euclidean geometry was necessarily true of our world. Ilse Rosenthal-Schneider, rather than reject this, sought to import some of the structure of Kant’s ideas into our understanding of general relativity, seeking a “Kantianized Einstein.”
I am interested in contributing to the growing body of interpretive work on Hermann’s philosophy of physics, and how she responded to the idea that quantum mechanics undermined causality. This intersects with the epistemological considerations involved in the third chapter of my dissertation, about what fundamental principles we could be forced to give up in the face of experience. Of course, in Hermann’s work, the stakes are much higher, since the universal applicability of causation is a much more substantive claim than that of classical logic (as is reflected in the fact that Kant saw classical logic as analytic, and causation as synthetic). In “Hermann and Kant: How Could Synthetic A Priori Truths Constrain Science?”, I will evaluate Hermann’s efforts to meet the challenge, in particular her insistence that finding a flaw quantum mechanics wouldn’t be enough to defend casuality’s a priori status. I will ask whether Hermann’s preferred defense of the a priori status of causality is more philosophically appropriate, and in what sense strict deterministic causality is ineliminable from physical theory.
I also want to ask how well the idea of a neo-Kantian moving a priori, that shifts with developments in science, fits with Kant’s larger transcendental idealist system. The background is that early in the 20th century Kant’s synthetic a priori claims about space were under attack. While different attempts have been made to defend Kant’s original claim, one proposal that Michael Friedman has recovered is that claims about space-time play a certain functional role in physics, one that deserves the title a priori relative to the physics of a particular time. One view that might seem to fit this template is that of Ilse Rosenthal-Schneider, a student and interlocutor of Einstein, who described her work as offering a “Kantianized Einstein.” But of course the structure Kant assigned to the phenomena was supposed to have implications not only for physics but also for the wider system of transcendental idealism, which was supposed to reconcile physics and ethics as bodies of knowledge. In “Rosenthal-Schneider, Friedman, and the Possibility of a ‘Kantianized Einstein,’” I will ask how proposed changes in synthetic a priori claims about space propagate through Kant’s system.