  Intuitively the intuitionists seem right. Empirical investigation can tell us many things about the world, but it does not seem that it can tell whether certain acts are right or wrong, good or bad. This is not to say that our moral views are not revisable in the light of empirical findings.  For instance if science told us that a lobster’s neurological system is sufficiently advanced for it to feel pain, we’d revise our view about the permissibility of boiling them alive. But all that science would have told us is that lobsters feel pain when boiled alive. Science does not inform us that boiling them alive is wrong.  That seems to be something that cannot be known empirically.