Moral Utterances, Nihilism and the Negation Problem

I am working on an argument that expressivism is incapable of making sense of certain kinds of nihilistic utterances. Dave Shoemaker and the editors over at Pea Soup have been generous enough to allow me to post my argument there for feedback. I thought I'd put a note up here in case anyone would like to look at or participate in the discussion. There is a general link to Pea Soup on the sidebar. Click here for the discussion itself.