In my criminal law class at law school, we discussed four basic theories of “why we punish”: deterrence (“to keep them from doing it”), incarceration (“to keep those who do it away from us”), rehabilitation (“to help them stop doing it”), and retribution (“because they deserve it”). Any punishment should fall in line with your basic theory of punishment.
It seems to me that each theory of punishment, when applied and examined, ends up needing such a degree of retribution as justification that retribution may be said to be the primary theory. Deterrence is probably the most commonly-held theory in America, but if deterrence is our primary motivator, we should chop the hands off of teenage shoplifters; that would deter! We don’t do that because we don’t think they deserve to have their hands chopped off. That punishment strikes us as cruel and unusual in comparison to the weight of the crime. I find incarceration equally problematic (we could lock up criminals indefinitely), and rehabilitation is foolish because it doesn’t (can’t?) work. Ultimately, the other theories lead to obvious injustices unless they have retribution as a foundation, notwithstanding critics that claim the retributive theory is too “vengeful.”
One of the best explanations of the problems with the deterrence and rehabilitation theories is C.S. Lewis’ essay, The Humanitarian Theory of Punishment. In the essay, he argues:
[With respect to] the deterrent justification of punishment we shall find the new theory even more alarming. When you punish a man in terrorem, make of him an ‘example’ to others, you are admittedly using him as a means to an end; someone else’s end. This, in itself, would be a very wicked thing to do. On the [retributive] classical theory of Punishment it was of course justified on the ground that the man deserved it. That was assumed to be established before any question of ‘making him an example arose’