I think the metaethics sequence is probably the weakest of Eliezer's sequences on LW. I wonder if he agrees with that, and if so, what he plans to do about this subject for his rationality book.

This is somewhat of a concern given Eliezer's interest in Friendliness!

As far as I can understand, Eliezer has promoted two separate ideas about ethics: defining personal morality as a computation in the person's brain rather than something mysterious and external, and extrapolating that computation into smarter creatures. The former idea is self-evident, but the latter (and, by extension, CEV) has received a number of very serious blows recently. IMO it's time to go back to the drawing board. We must find some attack on the problem of preference, latch onto some small corner, that will allow us to make precise statements. Then build from there.

The linked discussion is very nice.