We discuss Kant’s conception of moral rationalism from the viewpoint of recent debates, which have distinguished different forms of moral rationalism. We argue that Kant’s version, ‘silencing’, is different and stronger than currently held versions of moral rationalism and that it also differs from versions of silencing that contemporary thinkers advocate. We then discuss Kant’s version of silencing in the context of the moral demandingness debate and argue that silencing can make a perfect duty very demanding. However, it is important that whilst in cases of conflict between duty and personal happiness the normative standing of the latter is silenced, silencing does not require that agents do all they can in the case of imperfect duties. We finally indicate the kind of latitude imperfect duties allow for, according to Kant’s strong form of Moral Rationalism.