Michael Ruse talks about his Darwinian approach to moral philosophy.
I am a philosophical naturalist. By this I mean (or at least my meaning includes) being eager to accept the findings of science and to use them in my philosophizing as far as possible. So, I start my thinking about ethics by looking to Darwinian biology on human social behavior and I come away with the belief that ethics – meaning by this substantive or normative ethics (“What should I do?”) – is a product of natural selection (on individuals) to further reproductive success. Substantive ethics is an adaptation like eyes and noses and penises and vaginas. I should say that (and I am still at the level of science) I don’t think there is any need of external ethical principles (Mind of God, non-natural properties, Platonic Forms) to get this result. So ethics in a sense is different from say our knowledge about railway engines. Without existing independent railway engines, I don’t see that you could have a science of railway-engine-ology. I don’t think you need these external referents to get ethics. Ethics in this sense is not so much about the real world as it is about social relationships between fellow species members.