The Supreme Court of Canada held last month that Canada's new youth justice statute excludes deterrence as a justification for punishment. The right is unhappy with this. Meanwhile, more and more American foreign policy seems to be based on the idea that America's enemies can't be deterred because they are irrational. The left sensibly object to this on the grounds that it is a recipe for permanent war.
Pith & Substance is always on the look out for that contrarian sweet spot where both left and right can be shown to be guilty of the same error, providing said contrarian with that smug sense of superiority we so desperately crave. This looks to be an opportunity.
Deterrence just means aligning incentives so that some very bad course of action -- braining somebody with a pool ball, say, or nuking Tokyo -- has costs to the person who might do it. The law of demand tells us that a course of action that has higher costs for the actor is one that is less likely to be taken.
Now, the principle that greater expected costs of an action will make it less likely ceteis paribus does involve the idea that the actor is, in some sense, rational. Conservative hawks think this is an excessively nice thing to say about Kim Jong Il, while liberal criminologists think it is a horribly mean thing to say about teenage miscreants. Even someone with less at stake -- the proverbial median voter on the Clapham omnibus -- might think experience puts in doubt the idea that fifteen-year-old boys and all-powerful hereditary Commie dictators guide their actions by the light of sweet reason.
This is where the much misused principles of Darwinian selection come in handy. As John Maynard Smith made us aware, rationality of the relevant sort (optimization of marginal benefit and cost, pursuit of Nash equilibria and so on) is the birthright not just of ponderous German philosophers, but of fungi and pond scum. While there are other, more hoity-toity sense of "rationality" and "reasonableness" -- and the Pithlord has no quarrel with these -- what holds for intestinal fauna holds for megalomaniacs and testosterone addled YOs. Sure, their vision of benefits and of expected costs may be a bit addled -- but all other things being equal, they still optimize on the margin.
Nobody seems to have a big moral objection to deterring rogue states, but there does seem to be a sense that the truly compassionate would not try to deter youth crime. Since a deterred youth crime is one that doesn't happen -- thereby saving both victim and perp some grief -- I don't get this on utilitarian grounds. I recognize that the folly of youth is a legitimately mitigating factor, but it seems to me that deterrence is the most humane rationale for the system. We don't know whether B.W.P. could have been deterred from terminating the life of his victim, but it would have been a good thing for both of them, so it is hard to see why a responsible government would enact legislation saying that such an objective is to be rigorously dismissed from consideration.