  Suppose, for the sake of the argument, that there are moral facts. Suppose even that the moral facts are properly thought of as at least compatible with science. One thing Moore’s Open Question Argument still seems to show is that no appeal to natural facts discovered by scientific method would establish that the moral facts are one way rather than another. That something is pleasant, or useful, or satisfies someone’s preference, is perfectly compatible with thinking that it is neither good nor right nor worth doing. The mere fact that moral facts might be compatible with natural facts does nothing to support the idea that we could learn about the moral facts.  David Hume seems to have been, in effect, pressing this point long before Moore, when he argued that no moral conclusion follows non-problematically from nonmoral premises (Hume 1739). No “ought,” he pointed out, followed from an “is”—without the help of another (presupposed) “ought.” More generally, there is no valid inference from nonmoral premises to moral conclusions unless one relies, at least surreptitiously, on a moral premise. If, then, all that science can establish is what “is” and not what ought to be, science cannot alone establish moral conclusions.