  It is often held that moral goodness has a kind of “magnetism.” Intuitively, the recognition of moral properties like goodness bears some sort of intimate connection to motivation—not in the sense of being sufficiently motivated by such recognition that one actually does the relevant thing but in the sense of being motivated to some degree to do it. The general idea that there is some intimate connection between moral judgement and motivation is usually referred to as “judgement internalism.” (see Darwall 1983: 54). It is not obvious how the non-naturalist can explain how the recognition of moral properties can motivate. Mackie famously argues that the defender of objective values must implausibly maintain that moral properties have a kind of special causal power to motivate people simply in virtue of their recognition of them. He argues that the recognition of moral properties must have a sort of direct influence on the will so that anyone who recognizes them is thereby motivated. Since a property with this sort of causal power would be unlike anything else with which we are familiar and fits poorly into our scientific conception of the world, Mackie argues that we should not believe in such properties. Mackie’s official target is the thesis that moral properties are objective, but it is clear from his discussion that non-naturalist interpretations of moral properties are supposed to be especially vulnerable to his line of argument. Indeed, Mackie’s argument seems to have two stages. First, he in effect argues that any plausible interpretation of our pre-theoretical beliefs about morality will presuppose non-naturalism. Second, he argues that non-naturalism is itself untenable.