I’ll wrap this up by saying why I care about the whole metaphysics and naturalism issue. I don’t know if it’s of any wide significance; after all, I’ve mainly been picking out a strand in naturalistic thinking and saying something about why I like it and why it fits my more science-centered prejudices. But in certain debates that I happen to care about, it matters.
What I have foremost in mind is the unending struggle over creation and evolution. Due, I suppose, to the nature of political disputes, defenders of evolution and divine design have both coalesced around what have become standard positions for each. Both involve views about metaphysics.
Almost everyone I know who defends evolution agrees that evolutionary science on its own does not settle questions about the gods. There are broader concerns here that go beyond a narrowly biological context, and certainly beyond anything that can be handled in a science classroom. But what has become the standard position in defense of evolution in education hardens this pragmatic stance. It makes a distinction between methodological naturalism and philosophical or metaphysical naturalism. Science, in this account, is defined by methodological naturalism, in that it is strictly a search for natural explanations for natural phenomena. Supernatural explanations cannot even be considered within science, and hence nothing in science can count for or against suitably transcendent supernatural realities. Again, this is a pretty hard stance. It doesn’t just mean that the philosophy department is the proper place to discuss the gods. (There may be very good pragmatic reasons why this is true.) It shades into saying that this belongs to the philosophers because it all comes down to a metaphysics of ultimate things, and philosophers are the ones to sort that out, if it can be done at all.
Now, I clearly think this view is mistaken. But I can see its attraction. It draws a hard and fast line to protect science in the classroom. It does not offend liberal religious supporters of evolution, because it blocks science-based critiques of supernatural claims. If a scientist, for example Richard Dawkins, argues that evolution counts against the reality of the gods (without settling the question), they can also be ruled out of bounds. Naturalism becomes just another metaphysical position, and therefore on all fours with other metaphysical positions as far as science is concerned. Politically, in an public environment where creationist sentiment is strong, such a view has a lot to recommend it.
But it has its vulnerabilities, and creationists can exploit them. My chief worry is this. One of the greatest assets defenders of evolution have is how creationism is associated with a lack of intellectual sophistication, even outright anti-intellectual attitudes. Many people who like to identify proper expertise and trust it will support evolution even without a deep knowledge of the science, because they can tell who in the public debate has the signs of substance and who does not. Put crudely, if distrust of evolution is associated with hicks, that can only help. But especially with the intelligent design movement, some of that advantage may be eroding. One reason, I think, is that intellectuals supporting ID spend a lot of effort criticizing the standard evolution-supporting conception of science and metaphysics. Some of that criticism has real bite, because the standard stance is at least unnecessarily hard. And even having a real intellectual debate at that level can only help the intellectual image of critics of evolution.
Now, politically, I’m not sure what is the best way to respond. The advantages of the standard view remain compelling, and I’ll go along with an awful lot that I don’t fully agree with if it helps keep creationist influence down. But those of us who think of ourselves as naturalists, and furthermore want to have an intellectually cogent critique of intelligent design (aside from considerations of political effectiveness), should, I think, move away from the standard view. That conception of science, metaphysics and naturalism is mistaken. In the long run, it may not even be the most effective.
This is just one exampleone that is closest to my particular interests. But, as I have been trying to indicate, there are good reasons to think that a nonmetaphysical naturalism makes better sense. Perhaps there are even some more practical contexts, such as the creation-evolution wars, where shifting emphasis away from metaphysics is a good idea.