KP: Honestly, I do not know what to make of your suggestion that souls and gods might turn out to be natural entities. “Natural” and “supernatural” are flexible terms, but I fear that if we stretch language that far it will break. Are you suggesting that gods and souls might turn out to be constituted of energy or matter and are thus denizens of the space/time universe and, ipso facto, subject to the laws of nature? I earnestly desire not to make a straw man of you (or Lewis for that matter), so I just have to say that I do not follow you here.
VR: Mostly, here I am trying to get clear on exactly what you are taking the constraints of naturalism to be. I \use a working definition of what a naturalistic world-view is supposed to contain, and my argument against naturalism is an argument against that. But then I am told that I am really attacking a straw man, that my argument works against materialism but not against naturalism, or that it works against reductive materialism but not non-reductive materialism, etc. If we say what is natural has to be constituted of energy or matter, or if you say that what is natural has to be a denizen of the space-time universe, in other words, it must have a particular location in space and time, and it must be subject to laws of nature, well, we have a start. I suppose that makes God non-natural, since God is not supposedly located in a particular place. But with the soul, it's a little tricky, since I don't see why a soul should have to lack a particular location in space.
KP: As for whether we ultimately explain in “mentalistic” terms or not, it is not at all clear to me that we have an either/or here. If mental happenings are fully realized by physical happenings, i.e., if we think, feel, imagine, desire, etc. with our brains (as I think we do), then we have a choice, depending on our interests at the time, of how we explain those mental happenings. I can say “I concluded that the defendant was indeed guilty on the basis of the cumulative evidence against him, his clear motive, and the shakiness of his alibi” when I am discussing things in a legal or philosophical context. If I am doing neuroscience I could talk about the causal relations between evolving brain states, in particular those states that realize my reasoning about the defendant’s guilt. Why should one type of explanation preclude or take precedence over the other? Isn’t all explanation wholly context-dependent?
VR: The problem has to do with how what our concept of the physical is. It seems to me that a physical explanation, if we are sticking with standard definitions and are not expanding the notion of the physical to include things it doesn't traditionally include, our concept of what it is for something to be a physical explanation, at least at the base level of analysis, is for it to lack four "mentalistic" characteristics. First, the explanation at the base level cannot include an purpose. Second it cannot include any intentionality. What a physical state is about cannot enter into the base-level explanation. Third, it cannot include any reference to normativity. No piece of matter, in the last analysis, goes where it goes because it ought to go there. Fourth, a naturalistic explanation of a material state cannot contain any reference to a first-person perspective. I take it the idea that naturalists typically have is that the laws the govern matter don't change because the matter is realizing a mental operation. And, according to the standard understanding of naturalism, the base level is causally closed. This doesn't mean that it's deterministic, it means that nothing outside the physical system can affect where a particular atom goes, whether it's an atom in a rock or an atom in a brain. If there is quantum-level indeterminism, it's brute chance and nothing more. Quantum mechanics doesn't provide a door for non-physical causes to enter. There are some pretty strict limits on what kinds of explanations can be offered at the base level, if we are going to be good naturalists. If you want to loosen the definition of the physical, be my guest, but then I'm going to have to ask what the parameters are, and what is being excluded. Otherwise, how can we exclude what use to be called souls, or what used to be called gods? I mean we can even call God the theon, to make His name a more scientific sound.
KP: Finally, might not the behaviorists or the eliminative materialists turn out to have been the consistent naturalists? No. Consciousness is as much a natural phenomenon as a hurricane. Like a hurricane, consciousness is complexly realized and difficult to model, but there is no reason whatsoever to see it as not amenable to human understanding or as inexplicable in physical terms. Behaviorism and eliminativism were, as Bertrand Russell said about positivism, ideas so bizarrely stupid that only a very educated person could ever have been made to believe them. They are monuments to the astonishing capacity of highly intelligent and educated ideologues to ignore the elephant in the room.
Yes, but you have to realize that these were attempts to be consistently naturalistic. When you introduce consciousness, you introduce all four of the types of explanations which I had excluded. By using brain-talk, naturalists often mask the fact that they are in fact using personalistic explanations to describe what the brain is doing. In which case I reply "Interesting fellow, Mr. Brain. Remarkable what he can do."
In the case of hurricanes, it seems to me that if you add up all the physicalistic in formation about where the water molecules are and what you are doing, it closes the question as to whether there is a hurricane. In the case of mental states, it seems to me that if you add up all the nonmental states, you don't get determinate mental states. The physical underdetermines the mental. There is a conceptual barrier similar to the kind of barrier that is said to exist between an ought and an is. Given the fact we define the physical in terms of a lack of the mental, you can't go from the physical to the mental and get a definite conclusion as to what mental state is present. You can't siphon off the mental to the realm of the mental, because that's precisely what we are trying to explain.