Abstract

Smith begins by noting the isomorphism between the rational transition to a psychological state from others and the derivation of a concluding proposition from premises in the deductive theoretical realm, and he argues that this isomorphism led Hume to think that the rationality of the psychological transition is to be explained by the deductive validity of the derivation. Generalizing, Smith argues, Hume concluded that the concept of a reason—that is, the concept of a consideration that justifies—must be prior to and explain the concept of rationality. The fact that there is no such isomorphism in the practical and inductive realms is therefore, Smith suggests, what led Hume to his inductive and practical skepticism. Pace Hume, however, Smith argues that we need not agree that the concept of a reason is prior to the concept of rationality: we have an independent idea of the coherence of a set of psychological states and this is sufficient to provide us with an account of what it is for beliefs and desires to be justified. But it remains an open question whether the Kantians are right that practical coherence can be extended as far as yielding justified desires to do as morality bids.