Moral error theorists argue that moral thought and discourse are systematically in error, and that nothing is, or can ever be, morally permissible, required or forbidden. I begin by discussing how error theorists arrive at this conclusion. I then argue that if we accept a moral error theory, we cannot escape a pressing problem – what should we do next, metaethically speaking? I call this problem the ‘what now?’ problem, or WNP for short. I discuss the attempts others have made (...) to respond to the WNP, and in each case I show that the responses fail to be satisfying. I then propose a new response to the WNP, which I call revolutionary relativism. I define revolutionary relativism, explain why it is preferable to the existing responses to the WNP, and defend it against the most problematic objections I anticipate that opponents might raise. I conclude that revolutionary relativism succeeds where previous WNP responses fail, and that if we accept a moral error theory, we should become revolutionary relativists. (shrink)