Non-cognitivism is a variety of irrealism about ethics with a number of influential variants. Non-cognitivists agree with error theorists that there are no moral properties or moral facts. But rather than thinking that this makes moral statements false, noncognitivists claim that moral statements are not in the business of predicating properties or making statements which could be true or false in any substantial sense. Roughly put, noncognitivists think that moral statements have no truth conditions. Furthermore, according to non-cognitivists, when people utter moral sentences they are not typically expressing states of mind which are beliefs or which are cognitive in the way that beliefs are. Rather they are expressing non-cognitive attitudes more similar to desires, approval or disapproval.
Cognitivism is the denial of non-cognitivism. Thus it holds that moral statements do express beliefs and that they are apt for truth and falsity. But cognitivism need not be a species of realism since a cognitivist can be an error theorist and think all moral statements false. Still, moral realists are cognitivists insofar as they think moral statements are apt for truth and falsity and that many of them are in fact true.
My view is that on metaphysical naturalism, moral noncognitivism is the most reasonable view. On this view, it seems at the most foundational level, morality could only be social convention, or perhaps some kind of evolutionary instinct. But in either case, you’re left with no objective foundation for morality (objective meaning true or false regardless of what anyone happens to think about it).
But since I do believe in objective morality, and real moral duties, and that some acts are inherently immoral, those are all reasons I don’t believe in metaphysical naturalism.
Any thoughts along these lines?