Abstract

The moral error theory, it seems, could be true. The mere possibility of its truth might also seem inconsequential. But it is not. For, I argue, there is a sense in which the moral error theory is possible that generates an argument against both non‐cognitivism and moral naturalism. I argue that it is an epistemic possibility that morality is subject to some form of wholesale error of the kind that would make the moral error theory true. Denying this possibility has three unwelcome consequences such that allowing for and explaining it is an adequacy condition on meta‐ethical theories. Non‐cognitivism and moral naturalism, I argue, cannot capture the epistemic possibility of wholesale moral error and so are false. My argument additionally provides independent reason to accept Derek Parfit's claim that if moral non‐naturalism is false then nothing matters. I conclude that whether wholesale moral error is epistemically possible may be, in Richard Rorty's words, ‘one of those issues which puts everything up for grabs at once’ and that even if so, and even if non‐cognitivists and moral naturalists remain unmoved by an argument based upon it, this only helps to highlight the significance of my argument.