 As the Categorical Imperative indicates, in virtue of the humanity in them that persons are, and so ought to be treated as, ends in themselves. Commentators generally identify humanity (that which makes us distinctively human beings and sets us apart from all other animal species) with two closely related aspects of rationality: the capacity to set ends and the capacity to be autonomous, both of which are capacities to be a moral agent (for example, Wood 1999; Hill 1997; Korsgaard 1996). The capacity to set ends, which is the power of rational choice, is the capacity to value things through rational judgment: to determine, under the influence of reason independently of antecedent instincts or desires, that something is valuable or important, that it is worth seeking or valuing. It is also, thereby, the capacity to value ends in themselves, and so it includes the capacity for respect (Velleman 1999). The capacity to be autonomous is the capacity to be self-legislating and self-governing, that is, (a) the capacity to legislate moral laws that are valid for all rational beings through one’s rational willing by recognizing, using reason alone, what counts as a moral obligation, and (b) the capacity then to freely resolve to act in accordance with moral laws because they are self-imposed by one’s own reason and not because one is compelled to act by any forces external to one’s reason and will, including one’s own desires and inclinations. The capacity to be autonomous is thus also the capacity to freely direct, shape, and determine the meaning of one’s own life, and it is the condition for moral responsibility. It is then, not as members of the biological species homo sapiens that human beings have dignity and so are owed moral recognition respect, but as rational beings who are capable of moral agency.