It is sometimes hard for those who have not thought very much about these matters to realize what a radical claim Darwinism, so defined, makes. The claim is that our concepts of purpose, value, and meaning—and many other related concepts—literally refer to nothing. Nothing exists in reality corresponding to these ideas. All that really exists is just matter, energy, physical forces, and the principle of natural selection. And with these scientific concepts, we are supposed to be able to give a complete account of everything there is to know about living systems, including ourselves.
So, let’s see if this is true—if it is really the case that the theory of natural selection, together with molecular biology and the rest, provides us with a conceptually and empirically adequate account of biological reality.
The first thing to observe is that the Darwinian explanatory framework cannot do everything it claims to do unless it strictly avoids invoking any normative concepts. That means it may neither appeal to any normative concepts explicitly, nor tacitly presuppose any such concepts. If it does explicitly invoke or tacitly assume such concepts, then—at best—it is begging the question of normativity, or—at worst—it is simply incoherent.