 More comically, the Cambridge Apostles seem to have had a serious disagreement in 1899 about whether “self-abuse” was bad in itself, Moore intuiting that it was and his opponents arguing that it was not (Levy 1981: 207–8). Now, how could Moore explain the intuitions of his opponents? Not by an encounter with badness, since anybody fully acquainted with badness and its relata would have been forced to admit that self-abuse was bad. The non-natural facts being impotent in this particular, he would have been driven back on natural causes (such as a taste for self-abuse) to explain the misperceptions of his degenerate opponents. Thus he would have been forced to admit that some moral evaluations could be explained without the aid of non-natural properties. But once this is admitted, a “Why stop there?” problem opens up. For after all, it would have been child’s play for his opponents to return the compliment, Moore’s self-denying intuitions being the obvious products of a Puritanical upbringing. Once we admit that some moral intuitions can be explained by natural, as opposed to non-natural, causes—which seems pretty obvious given the prevalence of moral “error”—it is hard to hold the line and insist that there are any of them that cannot be accounted for by temperament, upbringing, desire and taste. It is possible, of course, that some moral evaluations are due to natural, and some to non-natural, causes, but given that everybody admits that many of our intuitions can be given a naturalistic explanation (namely, the mistaken ones), Occam’s razor suggests that there is no need for the non-natural to explain those moral intuitions that we regard as correct. When supplemented by Relativity (which is what Russell seems to be hinting at) Explanatory Impotence provides a powerful argument against non-natural properties.