This fascinating story from the New York Times earlier this month describes the resurrection of a debate that had once seemed dead and buried — whether the death penalty deters murder.
A flurry of recent studies, it seems, argue that capital punishment prevents murders — between 3 and 18 murders for each execution, depending on the study.
Here, on the Death Penalty Information Center website, you’ll find links to some of those studies, and to criticisms of them.
This is the kind of unsettling but useful rebellion in scientific ranks that can remind one to reserve a bit of healthy skepticism about any and all claims that a scientific point is settled. It’s the essence of science that its conclusions are always subject to revision, no matter how thunderous the voice of authority and consensus in which a given theory speaks.
For all of my career as a journalist, it has stood as a settled question in social science that the death penalty has little or no significant deterrent effect. Now, “for the first time in a generation” (as the Times story puts it), that consensus view is coming under serious attack.
An intriguing feature of the new debate is that it largely pits economists against researchers in law, criminology and other social science fields. For economists, it is a matter of first principles that people respond to incentives and therefore that when the “cost” of an action rises, that action will become less common.
But this is an alien and difficult concept for great numbers of people.
To be sure, it’s only the first of many complexities, where murder is concerned, that a would-be murderer is by definition in an unusual frame of mind. He may not very rationally compare the costs and benefits of eliminating his romantic rival or turf-war enemy.
Then again, no one supposes, do they, that everyone who considers murder goes through with it? Or that moral scruples are the only reason they ever decide against it? If not, then, by defintion, we are assuming that would-be murderers in some fashion weigh the personal pros and cons of their choice.
Similarly, almost everyone can see the wisdom of the widespread modern legal practice of imposing a penalty for murder that is more severe than the penalty for any other crime. Doing otherwise would give robbers or rapists a dangerous incentive to kill their victims, because they could then eliminate witnesses without risking any stiffer punishment.
But to see this is to assume that criminals do respond to incentives.
Here’s a thought experiment: What if tomorrow was declared “Get Away with Murder Day”? What if, for one day, anybody could kill anybody and risk no worldly consequence?
Think Get Away with Murder Day might bring a higher than normal murder rate? If so, you think homicidal sentiments are affected by incentives.
Anyway, here are two questions:
1) Even under the old consensus assumption that the death penalty had no important statistical effect on crime rates, it stood to reason that the threat of execution deterred some murderers.
How many would have to be deterred to justify capital punishment as policy?
2) Perhaps the strongest argument against the death penalty is the danger of executing the innocent. While a wrongly imprisoned defendant may eventually be freed, nothing can be restored to one who is mistakenly killed.
How substantial does the risk of executing the innocent need to be to make capital punishment unacceptable no matter how strong its deterrent effect?