June 13, 2012 by galudwig
In a recent blog post on bloomberg, Betsey Stevenson and Justin Wolfers make the case against using sociological and criminological studies to defend or oppose the death penalty.
While I agree with their general argument, I find their title to be very misleading. The death-penalty debate is a market failure? If it is, the authors did not explain why. In fact, the market has nothing to do with this.
Uncertainty and the lack of ‘ceteris paribus’
Stevenson and Wolfers’ central argument is that studies that purport to quantify the effect of the death penalty on homicide rates are lacking in scientific rigor and their conclusions decided by political opinions.
Quoting a study by the National Academy of sciences they conclude that
existing research is not informative about whether capital punishment decreases, increases, or has no effect on homicide rates, and that such studies should not influence policy judgments about capital punishment.
One of the reasons for this lack of confidence in the findings of such studies is the following:
Even if the correlation between capital punishment and murder rates could be reliably estimated, that wouldn’t be enough to prove causation. For instance, more vigorous capital punishment probably occurs at the same time as other reforms to sentencing, prisons and policing. Unless these variables are measured accurately — and our existing criminal-justice statistics do not provide adequate measures — it is impossible to disentangle which reforms are driving the homicide rate.
This and other problems lead to what they call model uncertainty:
there are many seemingly plausible ways of looking at the evidence that yield dramatically different answers. [This] facilitates abuse in the midst of a politically charged debate. With so many plausible approaches, there’s nothing to stop researchers fishing for a flashy result that may further their careers or ideological objectives.
Of course, the same charge could be leveled at the whole body of empirical economics and virtually the entire field of sociology. After all, economists can quote countless empirical studies that “prove” how instituting a minimum wage somehow doesn’t cause unemployment.
Another example is the recent talk about the success of Estonia’s austerity policies, Krugman’s refutation based on empirical evidence, and Mitchell’s apt returning of the favor. This kind of endless back-and-forth clearly shows how there is no ‘ceteris paribus’ in the real world of historical events and how empirical ‘evidence’ can go in all directions, depending on who is interpreting the data.
The so-called ‘austrian’ school of economics, and Ludwig von Mises and Murray Rothbard in particular, have talked about this problem for many decades. It’s refreshing to see these sociologists admit that they have a problem, if only just for this particular issue.
But back to the issue at hand. Stevenson and Wolfers consider the fact that the death-penalty debate is driven by political opinion to be a representation of ‘market failure’:
The debate over the death penalty offers a vivid illustration of a tragic flaw in the market of ideas: Strong beliefs attract a lot more attention, and can have a lot more influence, than the truth.
This ‘market for ideas’ is somewhat free (but far from unhampered), but the problem here is not that some studies are political — this much should be obvious. The problem is that these studies are used by politicians to further their policies. Clearly not a market failure, but rather a failure of the political process.
To drive my point home, we are talking here about how studies may influence how a monopoly on violence may justify killing their citizens in the name of the people it purports to represent. We are talking about the ‘market of ideas’ being poisoned by bad science. But these ideas concern political questions.
Is it any wonder that the debate about a political issue is driven by political opinions and not by whatever the authors’ idea may be of detached, objective science?
The mainstream answer to perceived ‘market failures’ are government interventions. Characterizing the failure of the political process of being independent of politics itself — clearly an absurd proposition to begin with — as a ‘market failure’ begs the question of what ‘we’ should do about it.
If studies are not to be used in the death-penalty debate, then what? Sweeping rhetoric? Moral or religious arguments? As is most always the case, my opinion is that ‘we’, meaning ‘the state’, shouldn’t be involved at all. But that’s fodder for another post.