  Rational requirements of this kind have recently become a subject of lively philosophical debate. The idea that there are structural requirements on our attitudes appears to be common ground among philosophers who differ significantly in their views about the nature and scope of practical reason. It is accepted by most Humeans, for instance, who believe that there is no scope for the rational criticism of individual ends, and also by Kantians, who think that the requirements of reason ultimately constrain us to choose in accordance with the moral law. From the perspective of practical and theoretical deliberation, we commonly grant the force of these structural requirements, acknowledging a kind of rational pressure to bring our beliefs and intentions into compliance with the instrumental principle and other standards of consistency and coherence.