Kant’s project in ethics is to defend the conception of morality that he takes to be embedded in ordinary thought. The principal aims of his foundational works in ethics – the Groundwork of the Metaphysics of Morals and the Critique of Practical Reason – are to state the fundamental principle of morality, which he terms the “Categorical Imperative”, and then to give an account of its unconditional authority – why we should give moral requirements priority over non-moral reasons – by grounding it in the nature of free rational agency. Roughly the principle of morality gets its authority from the fact that it is by acting from this principle that we exercise our free agency. In these works Kant develops a distinctive account of the content of moral requirement (which is filled out in his later work, The Metaphysics of Morals). According to one version of the Categorical Imperative, we determine what sorts of actions are permissible or required in various situations by asking whether a principle of action is rationally willed as universal law for agents with autonomy. A second version of the Categorical Imperative derives the content of morality from the principle that we are to respect “humanity”, or “rational nature”, as an “end in itself” and never merely as a means. “Humanity” is the capacity for autonomous rational choice, and it includes the capacity to act from one’s own judgment of what one has reason to do, to set ends for oneself, and to guide one’s actions by values one finds it reasonable to accept. To hold that this capacity is an end in itself is to claim that it has an absolute value – a value that Kant terms “dignity” – that sets limits on the..