 Autonomy is central in certain moral frameworks, both as a model of the moral person — the feature of the person by virtue of which she is morally obligated — and as the aspect of persons which grounds others’ obligations to her or him. For Kant, the self-imposition of universal moral law is the ground of both moral obligation generally and the respect others owe to us (and we owe ourselves). In short, practical reason — our ability to use reasons to choose our own actions — presupposes that we understand ourselves as free. Freedom means lacking barriers to our action that are in any way external to our will, though it also requires that we utilize a law to guide our decisions, a law that can come to us only by an act of our own will (for further discussion see Hill 1989; for doubts about this reading, see Kleingeld and Willaschek 2019). This self-imposition of the moral law is autonomy. And since this law must have no content provided by sense or desire, or any other contingent aspect of our situation, it must be universal. Hence we have the (first formulation of the) Categorical Imperative, that by virtue of our being autonomous we must act only on those maxims that we can consistently will as a universal law.