Sharon Street’s evolutionary debunking argument is an epistemological challenge against moral realism. It is built upon the empirical assumption that evolutionary forces have played a significant role in processes of moral belief formation. The goal of her subsequent dilemma argument is not to deny the existence of moral facts or morality as a whole, but to show that the starting assumption leads to the conclusion that we should think our moral beliefs are probably not objectively true. In this paper, I will firstly clarify the epistemic aspects of moral realism. Then I will illustrate Street’s empirical assumption and the investigated relations between evolutionary influences and moral beliefs. After then explicating the dilemma that Street builds upon her empirical assumption, I shall elaborate prominent realist objections to her argument, and problems that afflict these realist objections. This leads us to the conclusion that none of the realist objections has successfully defended moral realism against Street’s debunking argument; however, Street needs to take some of their insights seriously, in order to improve her debunking dilemma
