From CNN:
They’ve sung his praises on social networking pages, calling him a “hero,” “the greatest man of our time,” “a legend.” They’ve said he deserves to be knighted and should be decorated with medals. They’ve cried out for his amnesty and have even proposed serving time for him.
The article is about the man who threw his pair of shoes at the former President of the United States. He was sentenced this week to three years in prison. The quote raises the question of whether we should allow a third party to serve jail time on behalf of (and instead of) the convicted criminal.
In the economic theory of criminal justice, a punishment is designed to make potential “criminals” internalize the costs imposed on society by their crime. The principle is that we can never know in advance whether any act should be allowed. There are always circumstances in which the private benefit exceeds the social cost and so we design the punishment so that the act will be committed if and only if that is the case.
For example, driving too fast raises the chance of an accident and the driver internalizes only half of the consequences of an accident. So traffic fines are set in order to cover the gap. (The fine equals the cost of the damage times the increased probability of an accident due to speed. This explains why the fine is small and why it is increasing in speed.) We understand that sometimes it is socially optimal to allow the driver to speed. For example, his wife may be about to give birth all over his nice upholstry. So we allow him to speed for a price. If the price is set correctly, he will choose to do so only when it is socially optimal.
As it turns out there are occasions in history when it is socially optimal to throw a shoe at the leader of the free world. A pair of shoes in fact. Since this is not always the case, there is a punishment for it which ensures that it will be done only when it is socially optimal. But here’s the problem. Let’s suppose that those who benefit from seeing a shoe nearly leave its heel print on the cheek of the departing Decider are prevented from ever getting within range. Then it is socially optimal to enforce a contract which appoints a representative who will be in range to do the throwing and to have a third party enjoy the video and then pay the penalty.
In fact, when the benefit of seeing said video is shared by millions around the world, but the benefit to each is not enough to outweigh the cost of the penalty, then it is optimal to allow each of us to volunteer to serve a small jail sentence in return for watching the shoe fly.
All part of bringing Western democracy and justice to the Middle East.
Cheap Talk 
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March 18, 2009 at 9:27 am
mk
I like the game-theoretic notion of justice as deterrence, but it has some weird consequences (which might well be desirable).
For example, if a teenager kills someone, and at the trial he marshalls evidence that he was beaten as a kid, and there is a robust relationship between being beaten and (increased likelihood of) violent crime, then the parents should pay part of the sentence for the murder.
This notion of responsibility flowing probabilistically to other actors can happen quite often. Replace “the kid” and “the parents who beat the kid” with:
1) “A person” and “the spouse who just cheated on him/her” (prompting violent rage with probability = P)
2) “A schoolkid” “all the other kids who make fun of him/her in school” (prompting resentment, isolation and even violence with probability=Q)
3) “a child” and “the parents who, before the child’s birth, observed genetic information indicating that their child was subject to greatly increased genetic propensity to violence” (in this case the “second punishable offense” is the act of giving birth!!)
4) “a drug addict who commits a murder” and “the person who introduced them to drugs”
Surely we have “control” over our actions (my actions are not statistically independent from my desires), but surely it is also true that our actions are often *more predictable than chance* given recent history. In some such cases, the perpetrators of that recent history may deserve part of the punishment for a crime.