The econometric evidence is there, for those who are open to it: Capital punishment does deter homicide. See, for example, the careful analysis by Hashem Dezhbaksh, Paul Robin, and Joanna Shepherd, "Does capital punishment have a deterrent effect? New evidence from post-moratorium panel data," American Law and Economics Review 5(2): 344–376 (available in PDF format here). Dezhbaksh, Rubin, and Shepherd argue that each execution deters eighteen murders. That number may be high, but the analysis is rigorous and it accounts for relevant variables, such as income, age, race, gender, population density, and use of the death penalty where it is legal. It's hard to read that analysis and believe that capital punishment doesn't deter homicide -- unless you want to believe it. I certainly wouldn't take "Ouija Board" Goertzel's opinion over that of careful econometricians like Dezhbaksh, Rubin, and Shepherd.John McAdams, a professor of political science at Marquette University, makes a succinct case for the death penalty, regardless of its deterrent effect:
Now, I must say that I don't care whether or not capital punishment deters homicide. Capital punishment is the capstone of a system of justice that used to work quite well in this country because it was certain and harsh. There must be a hierarchy of certain penalties for crime, and that hierarchy must culminate in the ultimate penalty if criminals and potential criminals are to believe that crime will be punished. When punishment is made less severe and less certain -- as it was for a long time after World War II -- crime flourishes and law-abiding citizens become less secure in their lives and property.
I'm a bit surprised . . . [by the] claim that "the burden of empirical proof would seem to lie with the pro-death penalty scholar." If we execute murderers and there is in fact no deterrent effect, we have killed a bunch of murderers. If we fail to execute murderers, and doing so would in fact have deterred other murders, we have allowed the killing of a bunch of innocent victims. I would much rather risk the former. This, to me, is not a tough call.I wish I'd said that.
(Thanks to my son for the lead to the McAdams quotation.)
Does Capital Punishment Deter Homicide?
Libertarian Twaddle about the Death Penalty
Crime and Punishment
Abortion and Crime
Saving the Innocent?
Saving the Innocent?: Part II
More on Abortion and Crime
More Punishment Means Less Crime
More About Crime and Punishment
More Punishment Means Less Crime: A Footnote
Let the Punishment Fit the Crime
Another Argument for the Death Penalty
Less Punishment Means More Crime