Trait X is fitter than trait Y in a population of organisms if those organisms have other biological traits T and live in an environment that has properties E. The theory of natural selection is filled with statements of this form.

I disagree with the widely held view that it is metaphysical necessity, not nomological, that matters in the mind/body problem.

"Methodological naturalism" and "metaphysical naturalism" are terms that often surface in the continuing battle between evolutionary biology and creationism/intelligent design. The methodological thesis says that scientific theories shouldn't postulate supernatural entities; the metaphysical thesis says that no such entities exist. In this debate, God is the supernatural entity at issue; the question isn't whether science gets to talk about mathematical entities if Platonism is correct.

If you have evidence that C1 is a cause of E, and no evidence as to whether C2 is also a cause of E, then C1 seems to be a better explanation of E than C1&C2 is, since C1 is more parsimonious. I call the version of Ockham's razor used here "the razor of silence." The better explanation of E is silent about C2; it does not deny that C2 was a cause. The problem changes if you consider two conjunctive hypotheses.

Deism claims that God creates the universe and the laws of nature and then is hands-off, with everything that subsequently happens in nature being due to natural processes.

It can be a necessary conceptual truth that pains are painful without this ruling out the physicalist thesis that immaterial minds are impossible or the thesis that conscious states supervene on physical states. The necessity involved in these claims is nomological necessity, not metaphysical necessity (assuming that these are different).

It is an interesting fact about model selection that the evidence at hand can indicate that a model known to be false will be more predictively accurate than a model known to be true. This opens the door to a kind of instrumentalism.