Justice and Virtue in Kant's Account of Marriage

Abstract

All duties are either duties of right (officia iuris), that is, duties for which external lawgiving is possible, or duties of virtue (officia virtutis s. ethica), for which external lawgiving is not possible. - Duties of virtue cannot be subject to external lawgiving simply because they have to do with an end which (or the having of which) is also a duty. No external lawgiving can bring about someone's setting an end for himself (because this is an internal act of the mind), although it may prescribe external actions that lead to an end without the subject making it his end. (Immanuel Kant, The Metaphysics of Morals)