To enhance the plausibility of naturalistic moral realism, David Copp develops an argument from epistemic defeaters aiming to show that strongly a priori synthetic moral truths do not exist. In making a case for the non-naturalistic position, I locate Copp’s account within the wider literature on peer disagreement; I identify key points of divergence between Copp’s doctrine and conciliatorist doctrines; I introduce the notion of ‘minimal moral competence’; I contend that some plausible benchmarks for minimal moral competence are grounded in (...) substantive moral considerations; and I discuss two forms of spinelessness that Copp’s moral naturalism could result in. (shrink)