Evolutionary debunking accounts claim that the evolutionary origins of our moral beliefs provide a problem for moral realists because evolutionary explanations of our moral beliefs have more plausibility than realist accounts. A certain kind of response, which I term ‘rationalist’ offers a dual response to evolutionary debunking. First, they offer a supposedly plausible account of how we acquire objective moral knowledge through use of our rationality. Second, they claim that certain moral beliefs are not amenable to evolutionary explanation. I argue that neither of these putative advantages survives further scrutiny. An appeal to ‘rational insight’, although it makes reference to a somewhat familiar faculty, gives no useful explanation of how we come to know moral facts. Moreover, the supposedly problematic moral beliefs are in fact amenable to evolutionary explanation. As such, rationalist accounts are, like other realist accounts, on the wrong side of the balance of justification against evolutionary debunking.