  Moral naturalism (as a form of cognitivism) maintains that, while a distinction can be drawn between moral facts and other kinds of facts, moral facts are among the natural facts of the world. An advantage of this position for explaining the possibility of moral knowledge is that nearly everyone who rejects global skepticism grants that knowledge of natural facts is possible. The moral naturalist, therefore, is in a position to argue that moral knowledge should not be more problematic than other kinds of knowledge of the natural world. A moral naturalist can, moreover, reply to the charge that moral facts are redundant for explaining the facts of the natural world by pointing out that the burden of proof is on the critic to demonstrate that those natural facts that are also moral facts have no explanatory power. Certainly they cannot be said to lack explanatory power for the reason that they are not part of the natural world. Nor can they be said to be inaccessible to empirical study, since as part of the natural world they are knowable through experience (Copp 1995, p. 27).