Only All Naturalists Should Worry About Only One Evolutionary Debunking Argument

Do the facts of evolution generate an epistemic challenge to moral realism? Some think so, and many “evolutionary debunking arguments” have been discussed in the recent literature. But they are all murky right where it counts most: exactly which epistemic principle is meant to take us from evolutionary considerations to the skeptical conclusion? Here, I will identify several distinct species of evolutionary debunking argument in the literature, each one of which relies on a distinct epistemic principle. Drawing on recent work in epistemology, I will show that most of these initially plausible principles are false, spoiling the arguments that rely on them. And we will see that each argument threatens only one popular view of moral psychology: a “Representationalist” view on which our moral judgments rely crucially on a mental intermediary—e.g. a sentiment, gut reaction, or affect-laden intuition—delivered by our evolved moral faculty. In the end, only one evolutionary debunking argument remains a menace: an “ Argument from Symmetry ” that I will introduce to the literature. But we will see that it should worry only all naturalists, pressuring them into a trilemma: give up moral realism, accept a rationalism that is incongruous with naturalism, or give up naturalism. Non-naturalists are free and clear.