 In maintaining, as he does, that Plato’s theory of the Forms depicts what objective values would have to be like, Mackie, in effect, subscribes to (and attributes to Plato) a view called existence internalism. According to existence internalism, a necessary connection exists between having a certain normative status and  motivation.[1]  A state of affairs couldn’t be good, for example, unless apprehension of it was capable of motivating, though it need not motivate overridingly. If an individual apprehends something and fails to be moved, then ceteris paribus, it isn’t good. As Mackie describes Plato’s view, objective values provide overriding motivation, and so the view reflects a particularly strong form of existence internalism. According to that form of existence internalism, a state of affairs wouldn’t be good or valuable unless apprehension of it would provide overriding motivation. The internalist character of Mackie’s Platonic picture curiously aligns it with contemporary views that similarly accept forms of existence internalism, while holding that the capacity for motivation in fact depends on a preexisting desire. Consider a view about reasons associated most prominently with Bernard Williams (1981). According to what is called internalism about reasons or reasons internalism, necessarily, if an individual has a reason to do an action, he must be able to be motivated to do that action. On Williams’ view, in order to be motivated, an individual must have some motivating attitude in her current “motivational set.” Roughly speaking, then, if a consideration does not motivate a person given her current desires or motivational set, it cannot be a reason for her to act. Both the views of Williams and of Mackie’s Plato posit a necessary connection between normative status and motivation, but the former view makes normative status depend, in a way the latter view would flatly reject, on an individual’s subjective motives. 