Defenders of Motivational judgment internalism (MJI) argue that in one sense or another, our moral judgments necessarily motivate us to some extent. One of the most prominent defenders is Michael Smith, who in his highly influential book The Moral Problem defends a form of moral rationalism, which is the view that moral reasoning is based on practical reasoning, and thus that moral facts can and are determined a priori. This form of rationalism Smith claims to entail his account about internalism.One (...) of the main merits of Smith’s account of moral motivation is that it allows for individual difference in levels of moral motivation, by making the claim that moral judgments necessarily motivate defeasible. Before elaborating on how Smith does so, I shall first discuss Smith's approach in The Moral Problem, which will also help to set out the basic assumptions that will be taken for granted within this essay. I will then look at the account that he provides, and assess it with respect to one of Russ Shafer-Landau's criticisms thereof. Shafer-Landau rather helpfully puts Smith’s case for his moral rationalism in the form of what he calls ‘the incoherence argument’. The strongest problem that Shafer-Landau has with this argument seems to be with the following claim: ‘it is irrational for an individual to not desire what his fully rational self would desire’. What I hope to conclude is as follows: Although Smith’s account of internalism can for the most part withstand this objection that Shafer-Landau makes to it, even though Smith himself does not demonstrate any incoherence in failing to desire what one’s fully rational self would desire, in that a different kind of incoherence can be defended through other means. This would however result in a requirement for Smith to make significant concessions to his project in The Moral Problem. (shrink)