Tuesday, July 07, 2009

Physics and Philosophy

Sean Carroll has a post up titled Does Philosophy Make You a Better Physicist? This is the sort of question that can be understood in several different ways, and so it's worthwhile to pin down a bit more clearly what Sean is asking by considering the different sorts of (not mutually exclusive) answers that could be given to it.

(1) Yes, obviously, because logic and ethics are parts of philosophy, and good luck trying to be a good physicist without logic or ethics. And better logic and ethics would clearly make you a better physicist in some sense.

(2) Yes, trivially, because physics itself is a form of philosophy, and always has been; the reasons we don't still call the sciences "experimental philosophy" are entirely due to the historical contingency of how the nineteenth century rearranged funding, curricula, and departments in philosophical subjects.

(3) Yes, in an indirect way, because philosophy involves higher-level thinking that generates questions; and thinking about, and asking yourself questions about, the adequacy of your interpretations, the cogency of your inferences, and the implications of your work is the sort of thing good physicists do. One might call this the Heisenberg answer, since Heisenberg uses it in several places: philosophers don't give physicists the answers, but they do often ask the right questions.

(4) No, obviously, because most of the things philosophers deal with are irrelevant to either physical experiment or physical theorizing.

(5) Unknown, because we have no clear reason to think one way or another about whether training in philosophy would lead to better results in physics.

Each of these depends on reading the question in a slightly different way; Carroll, I take it, is reading it in the way assumed by (5), namely, by taking it to be a question about whether physics would progress more adequately if physicists had better training in philosophy or better interaction with those who have it. And I think he's right that this is simply unknown. It would make sense that some sort of philosophy would conduce to progress in physics; philosophy is such an immense field that there's almost bound to be something useful. But at the same time and by the same token, it's such an immense field that it looks suspiciously like a field of haystacks that probably contain some needles somewhere: there's really no guarantee that what physicists would actually be trained in, or what their philosophical interlocutors were trained in, would be the parts of philosophy that would hold the key to progress at any particular point in time.

As for the Yes answers, it's pretty clear that the philosophy required is the sort of thing intelligent, thoughtful physicists already do for themselves, just by being competent physicists, although there are probably cases of (3) and perhaps (1) where it's handy to have an outsider asking questions as well, just to reduce the danger of tunnel vision.