"on "naturalism". I think it is unfair to criticize the term on the grounds that it does not have a clear and unique meaning. If you look at any similar philosophical term, such as even your favoured "idealism", you will find that they typically refer to a broad church of views that have a main theme in common."
I was quoting what you gave as reference for "naturalism". If you have your favorite specific version of it, please give your reference. As for my idealism, I cared to precisely define it in my essay, to make it specific without reference to tradition.
"As far as my stance is concerned, I mean two things by the term "naturalism". The first is that the results of scientific enquiry are not to be ignored when they are relevant to a philosophical enquiry. (...) However, I do also adopt a stronger version of naturalism, which you may want to brand "materialism", but would more properly be called "physicalism"."
As I explained in my general review of ideological divisions in this contest, I subscribe to your first meaning of "naturalism", which I call "scientism", while I reject physicalism as directly refuted by science, so that I classify it in the opposite side, that of "obscurantism".
"Here, the idea is that our best guide to what fundamentally exists in the world is physics, so I want a metaphysics that does not posit entities beyond those of physics, or at least one that does so only minimally"
Physics was remarkably successful, however I see a logical gap in your idea: did you mean "our best guide to all what fundamentally exists in the world is physics" ? Physics was remarkably successful for many things, however it does not mean that everything we can understand can be traced to it. I consider that much of psychology can't.
As for a "metaphysics that does not posit entities beyond those of physics", what about the entity "measurement" that appears necessary for the formulation of quantum physics ? The only coherent way I see to dismiss it that really does not care about such spiritualist things as the subjective appearance for observers is the Many-worlds interpretation, however I saw on your blog that you reject this interpretation, for reasons which, precisely, come down to such an attachment to subjective appearances, which amounts to give a fundamental ontology to conscious experience.
"I do think naturalism and physicalism are fairly mainstream positions in philosophy of science, so I don't think it is inappropriate to argue from them."
It can be indeed mainstream, however this does not mean that there is any rational ground for this mainstream view, other than collective irrational prejudice. As was pointed out by David Chalmers in his article Consciousness and its Place in Nature, p. 31:
"Many physicists reject [the mind makes collapse interpretation] precisely because it is dualistic, giving a fundamental role to consciousness. This rejection is not surprising, but it carries no force when we have independent reason to hold that consciousness may be fundamental. There is some irony in the fact that philosophers reject interactionism on largely physical grounds (it is incompatible with physical theory), while physicists reject an interactionist interpretation of quantum mechanics on largely philosophical grounds (it is dualistic). Taken conjointly, these reasons carry little force, especially in light of the arguments against materialism elsewhere in this paper."