Kantian paternalism (KP) allows for paternalistic interference in order to help agents achieve the rationally chosen ends that constitute their conception of the good. It offers a necessary condition on paternalistic interference because it recognizes that the moral and non-moral costs of such interference can sometimes outweigh its benefits. Central to KP is the notion that paternalism is warranted when agents exhibit a certain form of instrumental irrationality. Intuitively, there is a difference between an agent irrationally choosing inadequate means to her chosen end and an irrational agent choosing inadequate means to her chosen end. The main normative power is the power of instrumental rationality, the power to determine the most effective means to the ends that constitute the conception of the good. Characterizations of rational suicide treat an individual's interests in a realist manner, as if what constitutes an individual's interests is wholly independent of her actual attitudes.