Ed: Just because "thinking" exists, how do you get from asserting "thoughts exist" to asserting that a whole "supernatural" world must exist?
VR: First of all, it was Lewis who used the natural-supernatural distinction to present this argument. I don't even typically use the word supernatural, at least not until we have some definition of what "natural" is going to mean. And for me, you don't really have an adequate definition of "natural" unless you say that the "natural" is without purpose, without intentionality (or aboutness), without subjectivity (nothing has a point of view at the basic level of analysis) and free of normativity. All of these things are supposed to be "system effects" of a system that is lacks all these things at the bottom level. If you don't like that definition of "natural", and want a different one, that's fine, in which case we simply won't be arguing about naturalism in your sense. Even God is not supernatural automatically. We need a definition of the supernatural that makes God supernatural before we can say that. What is your definition of natural and supernatural?
Ed: Your AFR argument fails to impress because your assumptions about what may and may not arise in this cosmos of matter/energy are mere assumptions.
VR: No, I offer arguments based on what can emerge from a purely physicalistic universe. I have arguments to the effect that if ultimate reality is naturalistic *in the sense that I have indicated above*, then there can be no determinate content to our mental states. There is a lack of strict entailment from the set of physical facts to the set of mental facts, and yet the physical is supposed to determine everything, including the mental. It is a line of argument used by Quine, by Davidson, by Saul Kripke in his book on Wittgenstein, and by Thomas Nagel in The Last Word. It's not an assumption, it's an argument. Reject it if you want to, but it is an argument.
Ed: And because your assumptions regarding the "non-natural" nature of "reasoning" also fail to impress. Certainly a naturalist views the rise of consciousness and making "rational" distinctions among things as to their sameness or differences, as evolving among brain-body systems.
VR: Any arrangement of parts that are "natural" in the sense I have defined is nevertheless going to leave indeterminate the mental state. That is the central argument. So long as it is evolution that is defined in naturalisic terms, it is going to turn out to be the case that we do not literally add, subtract, multiply or divide numbers, because we can never have a thought that is uniquely about the number 2.
I am not going to make even the statement that God is supernatural until you tell me what your conception of natural as opposed to supernatural is. What are the constraints on the use of the term? I think I even had a blog entry once that said that I didn't care whether it turned out that God was supernatural or not. I don't. However, I do think that God, and the human mind, is supernatural in the sense that I have defined above. But not knowing what definition of supernatural you accept, I have no idea what to make of your statements about the supernatural character of mind.