In You Provably Can't Trust Yourself, Eliezer tried to figured out why his audience didn't understand his meta-ethics sequence even after they had followed him through philosophy of language and quantum physics. Meta-ethics is my specialty, and I can't figure out what Eliezer's meta-ethical position is. And at least at this point, professionals like Robin Hanson and Toby Ord couldn't figure it out, either.
Part of the problem is that because Eliezer has gotten little value from professional philosophy, he writes about morality in a highly idiosyncratic way, using terms that would require reading hundreds of posts to understand. I might understand Eliezer's meta-ethics better if he would just cough up his positions on standard meta-ethical debates like cognitivism, motivation, the sources of normativity, moral epistemology, and so on. Nick Beckstead recently told me he thinks Eliezer's meta-ethical views are similar to those of Michael Smith, but I'm not seeing it.
If you think you can help me (and others) understand Eliezer's meta-ethical theory, please leave a comment!
Update: This comment by Richard Chappell made sense of Eliezer's meta-ethics for me.
(1): I think it's a prominent naturalistic feature; as EY said above, in a physical universe there are only quantum amplitudes, and if two agents have sufficiently accurate knowledge about the physical configuration of something, including their respective minds, they have to agree about that configuration, regardless of that they possibly have different values.
(2): I'm personally a bit confused about Eliezer's constant promotion of a language that de-subjectivizes morality. In most debates "objective" and "subjective" may entail a confusion when viewed in a naturalistic light; however, as I understand Eliezer's stance does boil down to a traditionally subjective viewpoint in the sense that it opposes the religious notion of morality as light shining down from the skies (and the notion of universally compelling arguments).
In regards to infallibility, an agent at most times has imperfect knowledge of right; I can't see how subjectivity entails infallibility. I don't even have perfect access to my current values, and there is also a huge set of moral arguments that would compel me to modify my current values if I heard them.
(3) The "why right means promoting X and Y" question is addressed by a recursive justification as discussed here and very specifically in the last paragraphs of Meaning of Right. If I ask "why should I do what is right?", that roughly means "why should I do what I should do?" or "why is right what is right?". I happen to be a mind that is compelled by a certain class of moral arguments, and I can reflect on this fact using my current mind, and, naturally, find that I'm compelled by a certain class of moral arguments.
EDIT: see also komponisto's comment.
re: infallibility -- right, the objection is not that you could infallibly know that XYZ is right. Rather, the problem is that you could infallibly know that your fundamental values are right (though you might not know what your fundamental values are).