A simple statement of the argument from reason
You take all the physical descriptions and put them in the left-hand side of the equation. On that side, there can be no intentionality, normativity, subjectivity, or teleology. Add them together, and it looks as if they can't entail anything on the right hand side, the "mental" side of the equation, where we do find intentionality, normativity, subjectivity, and teleology. There is always room for indeterminacy, or, for that matter, room for zombies. The physical works just fine, but there's just no there there.
Yet the naturalist cannot deny that there is determinate reference. The arguments of the philosophers, the observational reports of the sciences, and the equations of the mathematicians must have determinate meanings. Otherwise, science is impossible, and the case for naturalism collapses.
Therefore, if naturalism is true, the very things that are supposed to support it, such as argument and reason, aren't real. Only in a universe where the marks of the mental are metaphysically fundamental are these things possible.
Labels: argument from reason