There is no author or legislator of the moral law. It is simply valid in itself in the nature or essence of things. We become autonomous only when we obey it, because then our will aligns itself with the objectively valid law, and our choice follows the same law as that we give ourselves. We can think of rational faculty (or the idea - the pure rational concept, not exhibitable in experience) as the legislator or author of the law because reason recognizes an objective standard, and to that extent is already aligned with objective moral truth.
Allen W. WoodKant thinks of judgment as a special faculty or talent of the mind, not reducible to discursive reasoning but cultivated through experience and practice.
Allen W. WoodKant did think he had a moral route back to rational faith in God, for those who need it, and he thought that at some level, we all do need something like it.
Allen W. WoodKantian ethical theory distinguishes three levels: First, that of a fundamental principle (the categorical imperative, formulated in three main ways in Kant's Groundwork); second, a set of duties, not deduced from but derived from this principle, by way of its interpretation or specification, its application to the general conditions of human life - which Kant does in the Doctrine of virtue, the second main part of the Metaphysics of Morals; and then finally an act of judgment, through which these duties are applied to particular cases.
Allen W. WoodVirtues consist not only of acting in certain ways, but in ways of caring and feeling.
Allen W. Wood