  An immediate difficulty with this debunking argument is that it assumes that moral beliefs are not about moral properties that are also natural properties and hence are empirically knowable and can interact causally with other natural properties (compare Sturgeon’s reply to Harman in Sturgeon 1985; see also Campbell 1996, on Ruse). Consideration of moral naturalism, that is, opens up the possibility that those of our ancestors who tended to respond positively to moral properties had an advantage in survival and reproduction, because these properties are causally connected with mutual well-being. There are many forms of moral naturalism that allow this approach to the compatibility of moral truth and Darwinian moral evolution (Brandt 1979; Sturgeon 1985; Railton 1986; Boyd 1988; Brink 1989; Copp 1995, 2008; Churchland 1998, 2000; Sober and Wilson 1998; Rottschaefer 1998; Casebeer 2003; de Waal 2006; Campbell 1998, 2009; Kumar 2017). Though the success of such theories depends on the details, they cannot be dismissed on the ground of parsimony, since moral truths would not presuppose properties of a special or non-natural kind. While the truths might be viewed as suspect in other respects, for example, they would be both normative and natural (Joyce 2006), we have already addressed such worries in the sub-section 3.3 on moral naturalism. They are not new problems occasioned by evolutionary theory. Finally, there is no special epistemic problem of circularity when it comes to understanding evidence for such a theory, other than what we have already discussed in 3.3. In short, the debunking evolutionary argument from parsimony, clarity, and non-circularity is by itself no threat to moral naturalism.