This paper argues that, with certain provisos, predicting one's future actions is incompatible with rationally deliberating about whether to perform those actions. It follows that fully rational omniscient agents are impossible, since an omniscient being could never rationally deliberate about what to do. Consequently, theories that explain practical reasons in terms of the choices of a perfectly rational omniscient agent must fail. The paper considers several ways of defending the possibility of an omniscient agent, and concludes that while some of (...) these may work, they are inconsistent with the aim of explaining practical normativity by appeal to such an agent. (shrink)

An important debate in moral philosophy concerns the thesis of internalism, of which the characteristic idea is that there is a conceptual link between moral judgment and motivation. According to the internalist, to judge that something is right is to be motivated to do it (at least under certain conditions). Externalists are those who deny the truth of internalism. There are two ways that either party to this debate may argue for their preferred position. The indirect approach requires defending an (...) account of moral judgment and showing (for internalists) that it entails there is a conceptual link between moral judgment and motivation or (for externalists) that it entails there is no such link. In contrast, the direct approach requires arguing in favor of one position without assuming any particular account of moral judgment. In this paper, I examine two attempts—one by Michael Smith and one by Sigrún Svavarsdóttir—to resolve this debate between internalists and externalists by using the direct approach. Smith attempts to do so in favor of internalism while Svavarsdóttir makes the attempt in favor of externalism. I conclude that both attempts fail. (shrink)