 The non-naturalist has a number of possible replies to Mackie’s objection. First, the non-naturalist might simply deny that moral properties are motivating in Mackie’s sense. Mackie’s argument seems to “load up” the concept of a moral property with a lot of baggage that the non-naturalist need not accept. After all, some people seem to make perfectly sound moral judgements but remain unmoved to action by them.  Some people care about morality and other people do not; one need not ascribe any mysterious motivational power to moral properties to explain why moral properties motivate when they do (see, e.g., Savavarsdottir 1999). This reply is fair enough so far as Mackie’s initial challenge goes, but it does suggest another related problem. For now we need some account of why some people care about morality and other people do not, since it is clear enough that this depends in some way on the person’s environment and constitution. The non-naturalist may well be able to give such an account but neither will this be a trivial task.