It is a heavy irony that it should be autonomy, the moral notion the world owes mainly to Kant, that is now invoked as the justifying ground of a right to die. For Kant, autonomy, which literally means “self-legislation,” requires acting in accordance with one’s true self – that is, with one’s rational will determined by a universalizable, that is, rational maxim. Being autonomous means not being a slave to instinct, impulse or whim, but rather doing as one ought, as a rational being. But “autonomy” has now come to mean “doing as you please,” comparable no less with self-indulgence than with self-control. Herewith, one sees clearly the triumph of the Nietzschean self, who finds reason just as enslaving as blind instinct and who finds his true “self” rather in unconditioned acts of pure creative will.
Leon R. Kass – Life, Liberty, and the Defense of Dignity: The Challenge for Bioethics p.216