Pulling hedonic utilitarianism out of ethical emotivism

Ethical emotivism is a non-realist moral theory[1] which says that there is nothing more to moral statements than exclamations of emotion. For instance, saying “murder is bad” is just the same as saying “boo murder”, or expressing that you get a “bad feeling” when you consider murder, but there’s nothing more to it than that.This is attractive if you start from a position of non-realism: You look around the universe, see no particular reason for moral facts to exist, except that people walk around saying “that’s bad”, “that’s wrong”, “leave that poor pigeon alone”. Furthermore, you yourself feel things subjectively that cause you to say “that’s bad” and so on.The ethical emotivist takes the minimum possible step: these things are just expressions of emotion, which is just another way of saying “you yourself feel things subjectively that cause you to say “that’s bad” and so on”. It’s not even really a moral theory, it’s just adding emotions and the exclamations they generate into the set of phenomena in the universe. There are electrons, and they make other electrons move in the opposite direction. There are stars, and they make planets orbit around them. And there are emotions, and they make you say “that’s bad” and other moral statements.Quasi-realismThere is a school of emotivism[2] called “quasi-realism”, which aims to apply some concept of consistency on top of ethical emotivism. For instance, if someone proclaims “murder is wrong” and “lying is wrong”, then it is also “legitimate” in some way to infer (at least for that person) that “murdering someone and lying about it is wrong”, without them having to say it.Here is a longer quote from a (as it happens, disparaging) Stanford Encyclopedia of Philosophy article (SEP) on the topic, making this point:Such a view may hold that although the underlying logical structure of the sentence “Stealing is wrong” is nothing more than “Stealing: Boo!”, it is still legitimate for ordinary speakers to use such language as “Fre