 In short, attempts to establish the burden of proof are as slippery and indecisive in the debate between the moral realist and the moral anti-realist as they tend to be generally in philosophy. The matter is complicated by the fact that there are two kinds of burden-of-proof case that can be pressed, and here they tend to pull against each other. On the one hand, it is widely assumed that common sense favors the moral realist. On the other hand, moral realists face a cluster of explanatory challenges concerning the nature of moral facts (how they relate to non-moral facts, how we have access to them, why they have practical importance)—challenges that seem much more tractable for the moral non-objectivist and often simply don’t arise for either the noncognitivist or the error theorist. This tension between what is considered to be the intuitive position and what is considered to be the empirically, metaphysically, and epistemologically defensible position, motivates and animates much of the debate between the moral realist and moral anti-realist.