Is Violence a Disease?

A few years ago an economist colleague of mine debated a professor from our university’s school of public health on gun violence and gun control. My colleague walked through the empirical evidence on the effects of gun control laws on crime, accidental injury, and other social ills, citing well-known studies by economists and legal scholars such as John Lott, John Donahue, Gary Kleck, Ian Ayres, etc. As Circle Bastiat readers probably know, the empirical social science evidence, while not conclusive, clearly suggests that stronger gun control leads to increased rates of gun violence.  The public health professor — an MD who also teaches in the medical school — ignored these issues entirely, instead telling emotional stories about ER patients he’d treated for gunshot wounds and how everything must be done to stop this “epidemic” of gun violence.

The two speakers were, of course, talking totally past each other. One approached gun control from a simple, “rational actor,” cost-benefit approach. Gun control laws may make it slightly more difficult for bad people to get guns and for good people to do bad things, accidentally or in the heat of the moment, with a deadly object. But gun control also makes it more difficult for good people to acquire and use guns defensively, to deter crime. The net effect is ambiguous, but the existing empirical evidence strongly suggests that the latter effect outweighs the former. (Of course, I’m ignoring for the moment the relevant normative, political, and Constitutional issues.) The other speaker did not see gun violence, and violence more generally, as the result of purposeful human action. Rather, he saw violence as a disease, like the flu or cancer, which — while affected in some ways by people’s preferences, beliefs, and choices — is basically an epidemiological problem.

Indeed, the epidemiological approach to gun control is gaining adherents. “Is It Time to Treat Violence Like a Contagious Disease?” asks Wired in its latest issue. MSNBC breathlessly reports a claim that the National Rifle Association “suppressed” an important study, “rigorously conducted by ten credentialed experts” and “appearing in the prestigious New England Journal of Medicine,” showing that owning a gun makes a person less safe, rather than more safe. But these studies, conducted by public health professionals rather than empirical social scientists, are typically marred by basic methodological flaws such as sampling on the dependent variable, failure to account for endogeneity and unobserved heterogeneity, and other problems that would flunk a first-year econometrics grad student. Jacob Sullum offers a nice summary of some of this literature. Sullum focuses on researcher bias (e.g., selective citation of the existing literature), but also discusses some of the most infamous gaffes, such as a 2009 paper in the American Journal of Public Health showing that gun owners were more likely to be shot than “similar” people not owning guns, but matching only on age, gender, and race, ignoring the fact that people who are more likely to be the victim of gun violence are more likely to own firearms — i.e., that the causation is reversed. (This is a typical problem of what econometricians call “identification,” for which there are several generally accepted remedies, all apparently unknown to the public health research community.)

My sense is that the basic problem is the disease model of violence. Medical professionals are used to running controlled experiments, using clinical trials, and are unaware of how to perform empirical social science research outside a laboratory setting, so they apply the epidemiological model to issues like gun control, not recognizing that the decision to engage in violent acts, like crime more generally, is a form of purposeful human action. It’s time for journalists and politicians to recognize that the disease model is fundamentally flawed, and to turn to the best available research by economists, legal scholars, and other social scientists trained in how to do this kind of work.

(NB: I’m not suggesting that the mainstream law-and-economics research on crime, based on neoclassical economics, is free from problems. Ignoring time preference. See Samuel Cameron’s thoughtful essay.)


  1. “public health workers deal with the spread of AIDS is by educating, by redirecting behavior, by changing norms in a community so that everyone uses a condom”

    Yes, but AIDS _is_ a disease. We got rid of smallpox largely by, you know, oh, nevermind. I suppose the main challenge is to figure out how to get latex onto the appropriate social organs! Yes, we must speak frankly about such dire problems!

  2. Is there anything I could say here which Thomas Szasz hasn’t already treated at length? Probably, but it wouldn’t be trivial to produce it.

    Treating something _like_ a contagious disease implies that it isn’t one.

    “It’s not immediately clear that these lessons, drawn from the epidemiology of largely drug- and gang-related urban violence, could apply to the Newtown or Aurora or Virginia Tech tragedies, but underlying factors transcend demography. “They’re part of the same syndrome,” said Slutkin, who likened the mass shootings to what epidemiologists called sporadic disease, while urban violence is endemic.”

    Do these people actually have anything to say, or do they just employ these metaphors to sound like they do? At least it is admitted that the leap from AIDS to gun violence isn’t “immediately clear”.

    “Jared Loughner didn’t simply have a mental health problem, but a violence problem.”

    Was it his problem or ours? Certainly dead men don’t have problems, so …

    That I feel obliged to include this disclaimer that I condemn Loughner’s actions saddens me.

  3. Some random thoughts..

    Violence is a human tool to used gain something whether it be something of value, something to control, or something to maintain such as life. It is a means to an end. To connect violence to anything other than humans is false, intentionally misleading and plays on the ignorance, stupidity and fear of social entities to create a perceived atmosphere that can be directed to a goal ie: a refinement on managing the mob mentality for a lynching rather than to wait for a judge.

    Violence is inherently a human concept to created to explain an action that occurs between two beings, including animals and other than human creatures, that is performed for a specific purpose to gain maintain or survive that

    If you are discussing human violence as it relates to guns then you must consider all forms of human violence that involves guns regardless of the source.

    If you are discussing just human violence then you must discuss all forms of violence including that which uses no tools to that which uses any available tools regardless of the source.

    The present concept of violence has been corrupted for political gain against those who would resist a tyrannical government yet that same concept of violence perpetrated in abortions is ignored and in other instances barely noticed. As in history being written by the victors, propaganda is written by those in power.

  4. While I believe this analysis is true isn’t it also true that the approach of the gun control advocates is to prevent treatment of the disease? What if we treat the flu by preventing anyone from taking the vaccine? Does it make sense to treat a broken arm by tearing down the swing set but not setting the bone and putting the limb in a cast?

    Would it make sense to attempt to test everyone to determine who had the flu virus and isolate them? Yet isn’t this the approach suggested when advocates attempt to profile violent individuals? Has anyone ever been successful with a violence profile in preventing a criminal from committing a crime?

    Yet aren’t these exactly the policies proposed by gun control advocates. If violence is a disease it is one with an extremely high mortality rate and so preventitive measures should be our most important goal. If violence is a disease we need the most effective preventative measures available and that is to kill the infection before it kills us.

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