Of course, one is free to interpret "moral realism" as you do -- it's a natural enough interpretation, and may even be the most common one among philosophers. However, this is not the definition given in the SEP. According to it, "moral realists are those who think that...moral claims do purport to report facts and are true if they get the facts right". This does not entail that moral realists think that moral claims purport to report objective facts. But isn't such a loose interpretation of "moral realism" vacuous? As you say:
If SEP's usage of "fact" is taken to mean "a fact about the person holding the moral belief", the fact being that the person does hold that belief, then I don't understand what it would mean to say that there aren't any moral facts (i.e. moral anti-realism).
The moral anti-realist can choose from among two main alternatives if she wishes to deny moral realism, which I understand as being committed to the following two theses: (1) moral claims purport to report some (not necessarily objective) facts, and (2) some moral claims are true. First, she can maintain that all moral claims are false, which is a plausible suggestion: perhaps our moral claims purport to be about some normative aspect of the world, but the world lacks this normative aspect. Second, she can maintain that no moral claims purport to report facts; instead, all moral claims express emotions. On this view, saying "setting cats on fire is wrong" is tantamount to exclaiming "Boo!" or "Ew!"
First, she can maintain that all moral claims are false, which is a plausible suggestion: perhaps our moral claims purport to be about some normative aspect of the world, but the world lacks this normative aspect.
That would still be discussing an objective claim - just one that happens to be false. On a part with discussing a mathematical proposition which is false, or an empirical hypothesis which is false: both of these are independent of the person who says them or believes in them. Just so, discussing normative aspects of the world - whether they ex...
Continuing my quest to untangle people's confusions about Eliezer's metaethics... I've started to wonder if maybe some people have the intuition that the orthogonality thesis is at odds with moral realism.
I personally have a very hard time seeing why anyone would think that, perhaps in part because of my experience in philosophy of religion. Theistic apologists would love to be able to say, "moral realism, therefore a sufficiently intelligent being would also be good." It would help patch some obvious holes in their arguments and help them respond to things like Stephen Law's Evil God Challenge. But they mostly don't even try to argue that, for whatever reason.
You did see philosophers claiming things like that back in the bad old days before Kant, which raises the question of what's changed. I suspect the reason is fairly mundane, though: before Kant (roughly), it was not only dangerous to be an atheist, it was dangerous to question that the existence of God could be proven through reason (because it would get you suspected of being an atheist). It was even dangerous to advocated philosophical views that might possibly undermine the standard arguments for the existence of God. That guaranteed that philosophers could used whatever half-baked premises they wanted in constructing arguments for the existence of God, and have little fear of being contradicted.
Besides, even if you think an all-knowing would also necessarily be perfectly good, it still seems perfectly possible to have an otherwise all-knowing being with a horrible blind spot regarding morality.
On the other hand, in the comments of a post on the orthogonality thesis, Stuart Armstrong mentions that:
This is not super-enlightening, partly because Stuart is talking about people whose views he admits he doesn't understand... but on the other hand, maybe Stuart agrees that there is some kind of conflict there, since he seems to imply that he himself rejects moral realism.
I realize I'm struggling a bit to guess what people could be thinking here, but I suspect some people are thinking it, so... anyone?