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Yesterday, we explored why it might not make sense to be too tough on crimes – the reason being is that raising the penalty on petty crimes at the same time effectively lowers the penalty on more violent crimes. This seems to be an unattractive and inescapable constraint in law enforcement. At some point, the marginal cost of committing a violent act must fall to zero in societies that impose the death penalty.

For those criminals committed to an act – if the penalty for committing that act is capital punishment, then any further violent act is essentially costless to commit. So, for a committed murderer, mass murder is only one small step away. Or for that same committed murderer, first torturing your victim and murdering them is no more costly to you than murdering them in a more “humane” way. This might raise two uncomfortable questions for you. First, what can we do as a society to deter such heinous acts, if we must inevitably run into this zero marginal cost problem?

That is not an idle question for law enforcement either. It has implications on the benefits side as well. One reason CEO pay has gotten so high is that it creates huge incentives for people below the CEO to work more productively in order to obtain the brass ring of becoming a CEO. That is great and I suspect it works pretty well. But once we accomplish that, where is the additional incentive going to come from once you become the CEO? The marginal benefit of good performance may not be as high or continuing to increase (I believe Arnold Kling raised this point in his book Unchecked and Unbalanced, but I actually forget when I first came across it). Now, I am no expert on contracting, but it appears that there may be a way to mitigate this problem on the benefits side. But the consequence of this decreasing marginal benefit is that the incentives for a CEO to continue to do great work are not as high as they were in trying to encourage him to become CEO in the first place (I will remain agnostic about whether the next 100 million is enough of an incentive to keep a guy working hard who already amassed $400 million or more).

The second and more intriguing issue for me is why we actually do not see much more mass murder and horrific violence than we already do? After all, there are fairly large numbers of violent people out there, and the marginal cost of committing those extra acts of violence are low. So either there is some other cost of moving from murder to mass murder that we are overlooking, or that the marginal benefits of moving from murder to mass murder are not sufficiently large.

I don’t know … but this question allows for an interesting empirical test to examine just how intense these incentives are. What one might do is to look at rates of really violent crime and mass murder in jurisdictions that have implemented the death penalty for murder versus the rates of really violent crime and mass murder in jurisdictions that have not implemented the death penalty for murder. The hypothesis would be that mass murder and other extremely violent incidents should be more likely in places where the death penalty is currently in force.

Of course, there is a huge problem with my idea. What is it? Well, in places that do not have the death penalty for “regular” murder, I suspect that there is no death penalty whatsoever. So, the crime of committing one murder or 10 murders or more is punished only by life in prison – in other words, the marginal cost of mass murder will not be higher in the jurisdiction without the death penalty if there is no difference in penalties for murder or worse. Empirically, there might be a way to deal with this, and there might be legal differences in the prosecution of criminals in each jurisdiction that might allow us to overcome this problem, but I have not thought about it much. I just throw it out there for consumption and as an idea for someone in need of an interesting economics paper topic.

UPDATE: Andy Nutting points me to this fascinating story.

One Response to “Mass Murder at the Margin”

  1. […] Here is a long post discussing it in detail. A student of mine sent the following to me: I have a parallel to what we talked about in class last week. My old high school just imposed a suspension on pantsing people. My brother was given a two day suspension and in-school suspension for doing this as an example, before the rule was known about. The penalty is now a 5 day suspension. I was having a conversation with my mother about the punishment not fitting the crime and I explained to her that having a penalty like suspension for pantsing may lead to mass pantsing or pantsing the underwear as well because they would get suspended anyway and that the school probably made their problem worse. She laughed at me and told me that high schoolers, specifically the young boys, don’t think that way and that the effect probably wouldn’t be as I described. I was wondering what you thought of this. […]

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