Alan Thomas

This paper interprets Bernard Williams's claim that all practical reasons must meet the internal reasons constraint. It is argued that this constraint is independent of any substantive Humean claims about reasons and its rationale is a content scepticism about the capacity of pure reason to supply reasons for action. The final sections attempt a positive reconciliation of the internal reasons account with the motivation for external reasons, namely, securing practical objecitivy in the form of a commitment to impartiality. Impartiality is given a contractualist interpretation in the limited sense that socialised agents have a central disposition to hold those reasons that are defensible to reasonable interlocutors, but this is not a substantive constraint on their content. Such a commitment plays a structural role in motivation illustrated by the analogy of the internalisation of a relativised a priori principle. Theorists of moral motivation such as Nagel and Scheffler have uncovered the importance of such structural motivations, but they are best treated as an architectonic feature of a socialised agent's motivational set, not as a principle or motive akin to other principles or motives within that set. This gives us critical leverage on the motivational sets of individuals that goes beyond launching "optimistic internal reasons" statements at them, but it does not violate Williams's constraints on the idea of a practical reason in general