Is he operating outside the Aristotelian mainstream?
No, I kind of agree with that, though I don't think he knows what he's getting himself into. An appeal to intuitions doesn't take Aristotle out of the objective morality game, and the 'function argument' is pretty preliminary.
Aristotle's ethics is monumentally, catastrophically evil. I think it's also the perhaps the only real ethical theory we've ever come up with, which is a problem. Aristotle isn't okay with slavery, he positively argues for it. He would say that if we didn't have slavery, we should start, because slavery is a good thing. He thinks infanticide is a reasonable way to deal with population issues because children are ethically valueless. He is super evil.
Today's post, Three Fallacies of Teleology was originally published on 25 August 2008. A summary (taken from the LW wiki):
Discuss the post here (rather than in the comments to the original post).
This post is part of the Rerunning the Sequences series, where we'll be going through Eliezer Yudkowsky's old posts in order so that people who are interested can (re-)read and discuss them. The previous post was Magical Categories, and you can use the sequence_reruns tag or rss feed to follow the rest of the series.
Sequence reruns are a community-driven effort. You can participate by re-reading the sequence post, discussing it here, posting the next day's sequence reruns post, or summarizing forthcoming articles on the wiki. Go here for more details, or to have meta discussions about the Rerunning the Sequences series.