I start from the presupposition that the use of force against another is justified only in self-defence or in defence of others against aggression. If so, the main work of justifying punishment must rely on its deterrent effect, since most punishments have no other significant self-defensive effect. It has often been objected to the deterrent justification of punishment that it commits us to using offenders unacceptably, and that it is unable to deliver acceptable limits on punishment. I describe a sort (...) of deterrent theory which can avoid both of these objections. (shrink)