This is kind of what he's saying. Aristotle isn't playing the "lets do ethics from scratch" game. He says explicitly that he is counting on his and his student's intuitions to get the whole thing going. Ethical philosophy, he says, is only possible for people who were raised well and generally have a pretty good idea about right and wrong and stuff.

Really? I'm reading Ed Feser right now, and he's arguing very strongly that the only reason we don't have objectively grounded ethics right now is that we're not Aristotelians, and that the ability to objectively ground ethics is one of the biggest advantages of Aristotle over everyone else. He specifically attacks utilitarianism from an Aristotelian viewpoint for giving a moral criterion but not being able to prove from first principles that one should follow it.

Is he operating outside the Aristotelian mainstream?