Punishment in general is physical evil accruing from moral evil. It is either deterrent or else retributive. Punishments are deterrent if their sole purpose is to prevent an evil from arising; they are retributive when they are imposed because an evil has been done. Punishments are, therefore, a means of preventing an evil or of punishing it. Those imposed by governments are always deterrent. They are meant to deter the sinner himself or to deter others by making an example of him. But the punishments imposed by a being who is guided by moral standards are retributive.
(Immanuel Kant, Lectures on Ethics, trans. Louis Infield, The Library of Religion and Culture, ed. Benjamin Nelson [New York: Harper & Row, 1963 (first published in 1930)], 55)
