  What makes it questionable to construe Mackie’s argument as an inference to the best explanation is that his way-of-life explanation seems completely neutral as to the existence of moral facts. The account is illustrated by the claim that “people approve of monogamy because they participate in a monogamous life” rather than the other way round, and that view is surely consistent both with the existence and the non-existence of moral facts. It is accordingly hard to see how the alleged superiority of Mackie’s way of life-explanation of moral diversity confirms the idea that it is best explained by assuming that moral facts do not exist.