Browsing in the Harvard Bookstore in Cambridge, MA last week, I looked at the first chapter of Stephen Hawking and Leonard Mlodinow's 2010 book "The Grand Design".  I was hit by this:

How can we understand the world in which we find ourselves?  How does the universe behave? What is the nature of reality?  Where did all this come from?  Did the universe need a creator? ...

Traditionally these are questions for philosophy, but philosophy is dead.  Philosophy has not kept up with modern developments in science, particularly physics.  Scientists have become the bearers of the torch of discovery in our quest for knowledge...

It's not only wrong, but even, I think, a bit arrogant to dismiss philosophy as dead.  Have these guys even read any contemporary philosophy of science, or mind? Have they been to any conferences on the philosophy of physics recently, like maybe New Directions in the Foundations of Physics?  Have they read Oxford philosopher David Wallace's recent work on the "many-worlds" interpretation of quantum theory which, although I'm quite out of sympathy with it, I think is genuine progress in understanding how one might make sense of --- and what are the obstacles to making sense of --- this view of quantum theory, which is subscribed to by some though certainly not all practicing physicists and cosmologists?   For that matter, are they not aware of the close interaction between some philosophers of science and cognitive scientists?  Or the attention that philosophers Paul and Patricia Churchland have paid to neuroscience (not that I agree with their views)?

So that's one point, that philosophy is hardly ignoring science.  I argue below (and the Wallace example already provides some evidence) that it has useful contributions to make to those parts of physics that deal with the kinds of big questions Hawking and Mlodinow raise.  But one other point needs to be made, which is that philosophy has much broader concerns, involving politics, morals, the good life, aesthetics, and social science, and in these areas too, it is alive and well and contributing.  I sincerely hope Hawking and Mlodinow don't think science is "the torch-bearer" there too, because although of course it is not irrelevant even there (probably no part of human thought can be declared a priori completely irrelevant to any other) that is a torch it is not capable of bearing.  If they really do think science is the torch-bearer here, I think they are contributing to the stunting of serious thought in these areas that are just as important to humanity as science, and indeed, to a stunted conception of humanity.

Now, I can dig that Hawking and Mlodinow, if they were to attend New Directions, might think that some of the stuff being done is not of interest.  In particular there is usually not that much philosophical discussion around string theory and M-theory, although quantum cosmology does come up on occasion.  Maybe they are not interested in the quantum foundations issues like "is the quantum state epistemic?" that come up frequently in New Directions.  I wouldn't be surprised, though, if there are other philosophy conferences that I don't attend where M-theory and quantum cosmology get much more attention.  Maybe they might think some of the stuff aimed at understanding the conceptual content of physical theories like general relativity that have been around for about 3/4 of a century, and comparing them to older theories like Newton's and heck maybe even Aristotle's, is pointless.  I'm referring to James Weatherall's excellent talk "Explaining intertial motion and the foundations of classical space-time theories".  (Here's a link to the paper the talk is based on.) But I'm speculating here; maybe they'd love it, realize that it's worth thinking about the conceptual structure of existing theories as one tries to incorporate what was good about them and go beyond (combining classical general relativistic space-time theory with quantum theory).  Or maybe they'd think it was all understood by physicists long ago, so while not pointless, just not contributing to progress.

Here's yet another point.  I frequently read or hear physicists spouting some methodological priniciple they got from some philosopher of science, often Karl Popper, or some view that is common in some branch of science but considered by philosophers to be quite problematic.  Sometimes it is used to good effect, sometimes used in a quite unsophisticated manner, with little consciousness of drawbacks and caveats well-known to philosophers.  For instance, some physicists freely use the frequency interpretation of probability with little or no understanding of its serious difficulties.  I have heard one of the world's most renowned cosmologists do this, and in response to my objections, dismiss the "Bayesian personalist" (sometimes called "subjective") view of probability by saying something along the lines of  "I'm not interested in betting, I'm interested in describing the world"), although I have also found that other reknowned cosmologists do have an active interest in the "personalist" interpretation of probabilty.  I suspect there are plenty of other places where, when physicists start addressing questions formerly thought of as "philosophical", or when they use philosophical principles or positions in formulating their physical theories (or their "interpretations" of such theories, which one might argue are really an essential part of the theories themselves), philosophers can help physicists avoid making both elementary and subtle philosophical (or perhaps we should just say conceptual) mistakes.

I have no problem with the view that the questions posed by Hawking and Mlodinow in the above quote are not just the province of philosophy, but require input from what used to be called "natural philosophy": science, including physics.  Nor do most contemporary philosophers!  But some of the careful conceptual analysis that philosophers have done, over the course of the twentieth century, of notions like truth, confirmation, induction, falsification, refutation, meaning, reality, perception, observation, theories, and so forth, is enormously relevant to any attempt to say what current physical theories, and speculations like M-theory, really mean for "the nature of physical reality".  It is cool that Hawking and Mlodinow are engaging in this attempt, and I plan to get their book out of the library and see what they have to say.  Perhaps I will even end up thinking that they have made enormous progress.  But I think they are foolish to dismiss the potential for contribution by philosophy to this enterprise.  Indeed, in their description on pages 6 and 7 of their philosophical approach, they say plenty of things that are easily found in the "analytic" philosophy of the latter part of the 20th century:  for example "we shall adopt an approach we call model-dependent realism.  it is based on the idea that our brains interpret the input from our sensory organs by making a model of the world.  When such a model is successful at explaining events, we tend to attribute to it, and to the elements and concepts that constitute it, the quality of reality or absolute truth.  But there may be different ways in which one could model the same physical situation, with each employing different fundamental elements and concepts.  If two such physical theories or models accurately predict the same events, one cannot be said to be more real than the other; rather, we are free to use whichever model is most convenient."  Well, philosophers have been discussing this possibility for decades.  Most usually, it is called "the underdetermination of theory by evidence." So, probably, have physicists; I am not sure in which community the possibility was first mooted, or whether it has occurred many times independently.  I'm looking forward to seeing what use Hawking and Mlodinow make of this possibility, but I consider it a strong possibility that the philosophers who have thought about it carefully may have something useful---useful to physics---to say about its use in physics, or in the application of physics to the big questions Hawking and Mlodinow aim to address.

Okay, enough rant.  I want physicists to think about the big questions; I hope Hawking and Mlodinow have genuine insight on them.  I'll report on that as I read their book.  But I really, really think it is miguided to dismiss the possibility that the field of philosophy as currently practiced has anything to contribute here.   And it goes beyond misguided to downright pernicious, and perhaps to a kind of narrow-minded science triumphalism which is, frankly, morally dangerous, to claim that "philosophy is dead" and that science is bearing its torch.  Let's hope that philosophers and physicsts continue to join forces where appropriate, as we do at New Directions, and indeed that they expand cooperative efforts, to deal with the big questions Hawking and Mlodinow want to address, to deal with other big questions, to deal with issues of how physics might best progress, how the insights of quantum theory and general relativistic spacetime theory can be combined into a more unified physical theory, and to understand better how physics and science fit into the broader picture of rational, and irrational, human activity.