  Mackie’s objection relies on the highly controversial premise that moral judgements necessarily are motivating and as we have seen the non-naturalist might reasonably just deny that premise (that was the first of the three replies discussed above). However, one might instead appeal to the much more modest premise that if an agent judges that some possible action of hers is morally required then she will be motivated to perform that action unless she is practically irrational. Michael Smith refers to this as the “practicality requirement on moral judgement” (see Smith 1994: 61). This requirement seems plausible because the recognition that an action is right plausibly is the recognition that the action is well-supported (perhaps conclusively supported) by justifying moral reasons for action, and such a recognition should motivate someone unless the agent is practically irrational. For present purposes, the point is that even if Mackie’s challenge can be bypassed or met in one of the three ways just discussed, a further challenge concerning motivation still faces the non-naturalist. For if the practicality requirement on moral judgement is correct then the non-naturalist needs to provide some account of why an agent’s recognition that one of the actions available to her has the non-natural property of rightness is such that her recognition of this fact rationally requires that she be motivated to perform the action.  In particular, some account of why judging that something is well supported by reasons (understood in non-naturalist terms) is appropriately connected to motivation.