Clayton: Suppose the dualist and the physicalist square off. The dualist believes in mental substances and the modes, attributes, properties of such substsances along with physical substances and their modes and attributes. The physicalist believes in only physical substances. The dualist says that no description of the physical substance will allow us to work out 'what it's like' to taste chocolate or see red. The physicalist response is that no description of the mental substance will allow us to work it out either. Doesn't that mean that there's something wrong with the suggestion that to determine the ontology of the mental, we try to see what can be worked out from descriptions of the relevant substances?
VR: But when you look at what could possibly count as physical, you have constraints concerning what can be put in the basic level of analysis, and given those constraints, you can't "build up" to intentionality. If you lift those constraints, then intentionality fits in without difficulty.
To have a genuinely and consistently naturalistic view you perforce have to leave out intentionality or aboutness, purpose, subjectivity or perspectivality, and normativity. If we something exists because it means something else, if we say something exists because it serves a purpose, if we say that it does something because of its own point of view, if we say it does something because it satisfies some norm, then we are in effect mentalizing the supervenience base, unless we are expecting an analysis of a supervenience base that lacks all these things to entail states of this type.
For example, if we consider the position of the bricks and mortar to be the supervenience base, then it seems to me that a combination of these is going to give us a "brick wall" even though the word "wall" doesn't appear in the supervenience base. There is no logico-conceptual gap between walls on the one hand and bricks and mortar on the other. Rather, a wall is a set of brick and mortar states taken together.
But in the case of the mental, so long as you keep the four elements I listed above out of the supervenience base, it isn't going to add up to something in which those four elements exist. The logic doesn't work. There is always going to be a logical gap between something without those four elements and something with them. Listing truths in the constrained supervenience base is always going to leave the mental states indeterminate.
However, the problem can be overcome by lifting the contraint on the supervenience base. Dualism is one way of doing that, absolute idealism is another.
However, if you assert that the physical universe began with only elements which lacked these four elements (the description of the universe at the Big Bang doesn't seem very mental to me), then if those elements now exist, we need a fundamentally non-physical explanation to explain why they now exist.
If you read C. S. Lewis's books, especially Miracles: A Preliminary Study, you find that Lewis argues separately against Absolute Idealism and Pantheism. He doesn't use any version of the Argument from Reason.