Kant on the motive of (imperfect) duty

This paper argues that Kantians face a little discussed problem in accounting for how actions that fulfill imperfect duties can be morally motivated. It is widely agreed that actions that are performed from the motive of duty are performed through a recognition of the objective necessity of the action. It is also generally held that the objective necessity of an action consists in its rational non-optionality. Many actions that fulfill imperfect duties, however, are rationally optional. Given these constraints, it is impossible that such rationally optional actions (including, for instance, many acts of benevolence) could be performed from the motive of duty. After presenting the problem as one that Kantians should find genuinely pressing, this paper offers a solution by advancing an alternative to the conception of rational necessity widely shared by Kantians. On the alternative view presented here, an action is rationally necessary if and only if the justifying reasons that speak in favor of performing the action do not depend on any empirical and therefore contingent motivational source on the part of an agent. Such actions may well be rationally optional. Moral motivation is therefore possible even in the case of rationally optional actions.