Question: What is the role of a philosopher of science?
David Albert: Well, I think that philosophy of science is at its best and at its most exciting at historical moments when it's not so easy to distinguish between the activities of certain kinds of theoretical physicists and the activities of certain kinds of philosophers. Philosophy of science, I think -- or at least -- well, let me back up a bit. There's -- philosophy of science can be divided roughly into two different kinds of activities. One is an activity of raising and investigating general philosophical questions about what science is, about whether the claims of science have some kind of privileged epistemic access to the world, can be justified, attempts to systematize how science reasons, attempts to raise questions about whether we should trust the conclusions of science, so on and so forth. These are very broad, very traditionally philosophical kinds of issues.
There's another branch of philosophy of science that takes up questions that arise within particular scientific theories -- the theory of evolution, the theory of relativity, quantum mechanics, so on and so forth, and actually gets its hands dirty in the details of the structure of these scientific theories in order to try to help with problems that are often essentially scientific problems, but whose solution calls for an unusual degree of sensitivity to philosophical questions. It's the second kind of work that my own work has mostly been, and it's the second kind of work that one refers to when one refers to the foundations of physics. There are problems about the logical structure of physics, about the foundational assumptions that physics makes. Whether these problems properly belong to physics or they properly belong to philosophy when the field is healthy isn't much of an issue.
In my own case, my Ph.D. was in theoretical physics. I was a professor in physics departments before being a professor in philosophy departments. When I write a paper now, my rule is that if at the end it has more than two equations in it, I send it to a physics journal, and if it has less than two, I send it to a philosophy journal, and there's not much more of a distinction than that. When I attend conferences where people are discussing the kinds of questions that I'm interested in, about half of the people speaking at these conferences are employed in physics departments, and half are employed in philosophy departments, and it's not particularly easy to tell by listening to their talks what sort of department they're employed in. So philosophy of science, like I say, when it's healthy, is a matter of focusing with a certain level of philosophical sensitivity and sophistication on questions at the foundations of physics.