 Two follow up questions suggest themselves. One is about what “expresses” means here; for one answer, see Gibbard (1990). A second is about what the relevant difference in mental states consists in. On many views, the mental states expressed by non-ethical sentences are beliefs, whereas the mental states expressed by ethical sentences are not. Different versions of expressivism propose different candidates for the mental states which are expressed by ethical sentences. Prominent candidates include exclamations (Ayer 1936), commands (Hare 1952), and plans (Gibbard 1990, 2003).