Hi folks! Been a LessWrong lurker for a while. Here's a little project I'm excited about, which has been useful in organizing my thoughts on meta-ethics.
This piece is a walk-through of an original flowchart (made with lots of help from friends) that categorizes the major meta-ethical positions. It lays out the points where different meta-ethical theories diverge and gives a brief intro to each major theory. I think it's a nice tool for getting a sense of the broadest strokes of academic meta-ethics, and being able to hold the different theories in your head.
https://medium.com/@tommycrow/what-is-your-meta-ethical-position-c27939810985
Yes, Huemer writes: "Nihilism (a.k.a. 'the error theory') holds that evaluative statements are generally false."
I'm not sure how the term "nihilism" is typically used in philosophical writing, but if we take nihilism=error theory then it looks like non-cognitivism wouldn't fall within nihilism (just like non-cognitivism doesn't fall within error theory in your flowchart).
For the first diagram, Huemer writes "if we say 'good' purports to refer to a property, some things have that property, and the property does not depend on observers, then we have moral realism." So for Huemer, nihilism fails the middle condition, so is classified as anti-realist. For the second diagram, see the quote below about dualism vs monism.
Huemer writes: