Punishment consists in doing things to people which are expectedly undesirable from the point of view of the recipients. These have typically included the infliction of physical pain, deprivation of life itself, and, for long the standard form, deprivation of liberty of movement, in the form of a period in jail. We have a fairly strong prima facie duty to refrain from inflicting such things on anyone. (Some might even think that we have a rigorous, or “absolute” duty thus to refrain, but that would make punishment necessarily unjustifiable.) But if we accept any such duty—as we all do—then the question of justification for punishment obviously arises, for clearly we need to justify the doing of what is normally wrong. We need to show why certain kinds of non-normal behavior call for punishment.