Kant's Metaphysics of Morals

Most philosophers who have considered legal punishment suppose that penal institutions, either as they exist or at least as they would exist if they lived up to some normative concept of them, can be morally justified. Kant is best known as a subscriber to the first of the justifications of punishment. Kant's insistence on retributivism, that it is a fundamental moral principle or categorical imperative that moral evil deserves punishment is clear enough. Punishment is justified as a form of coercion used to protect right. Kant occasionally tries to present God's providential apportionment of happiness in accordance with worthiness as a case of doing retributive justice. Whatever opinions Kant himself may have held or expressed in favor of retributivism, Kantian ethics is seriously lacking as long as it cannot justify them or even consistently include them.