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November 19, 2007

Death Penalty and deterrence

The New York Times has a very well written article this weekend on the latest economic research into the death penalty by Adam Liptak.The first iteration of the article I saw was on the Chicago Tribune website which gave it a terribly misleading headline, "Scholars cite evidence that death penalty deters murders." I figured it was just going to be a typical, this group of scholars at some random think tank has found this result, but it wasn't at all.Liptak does a good job of summarizing a couple of recent findings and more or less comes to the conclusion that there just isn't enough variation in the death penalty to accurately measure its impact on crime rates or homicide. Liptak cites heavily from a paper by Penn stud Justin Wolfers and Yale Law School professor Jon Donohue. Last year I was luckily enough to see Donohue present the paper at the U of C law school and I blogged about it here.Here is what I walked away from that talk thinking:

What Donohue found was that in replicating past studies, changing some of the simplest parameters of the models caused the results to completely reverse (to the extent that results found that each execution actually caused more people to be murdered). One aspect of Donohue's was against the use of such sensitive results in emotionally charged debates, like the deterrent power of the death penalty or the impact on crime of guns. Such empirical research is extremely powerful, especially when it can be simplified into: X executions prevents Y murders.
But, after reading Liptak's article, I can't help but think about another failure of economics to inform this debate. Ultimately, I don't think it matters if the death penalty saves a couple of lives. The death penalty is a costly process, both financially and morally. There are plenty of ways that we can deter homicide. For example, we can do what Vonnegut's fictional island San Lorenzo would do to deter its population from practicing a certain religion: impale those caught with a giant hook.Of course, that would never jive with Americans, but my point is that the real question isn't whether the death penalty deters homicide, it's whether it's the optimal way of deterring the most number of murder. Economics does very little to educate this discussion.