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.

The big picture, I think, is that common ancestry is evidentially prior to natural selection in Darwin's theory and in contemporary evolutionary biology as well.

Another way to test hypotheses about adaptation is to consider trait variation across a group of species instead of focusing on the trait of a single species. Rather than seeking to explain why polar bears have fur of a certain thickness, one tries to explain why bears in colder climates have thicker fur than bears in warmer climates. The former problem is hard to solve, since it is hard to say exactly what fur thickness polar bears should have if natural selection guided the evolution of that trait.

Deism is compatible with evolutionary theory.

The more evolutionary theory gets called an atheistic theory, the greater the risk that it will lose its place in public school biology courses in the United States. If the theory is thought of in this way, one should not be surprised if a judge at some point decides that teaching evolutionary theory violates the Constitutional principle of neutrality with respect to religion.

In the history and literature courses I took, epistemological questions came to interest me most. What makes one explanation of the French Revolution better than another? What makes one interpretation of "Waiting for Godot" better than another? These questions led me to philosophy and then to philosophy of science.

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.