Why does an insurgent group choose suicide bombings over other types of attacks? Eli Berman and David Laitin apply economic theory and new data to this question and come up with some interesting opinions in what is one of the more interesting papers to come out of the NBER recently.

Theirs is part of a growing number of academic articles looking at the economic and political logic of terror tactics. See this article investigating the connection between poverty and terrorism, this one on education and the productivity of terrorists, or Perspective on Politics’ symposium on terror. (Sorry if these links are gated. Try Google for free versions.)

Berman and Laitin cite some of their past work on why religious fanaticism does not offer a convincing explanation for suicide bombings. Rather, they emphasize that suicide bombings are used when the conditions don’t favor standard insurgency tactics: when targets are hard and well-protected, and when capture of the attacker risks undermining the entire group. They even provide some suggestive data to support the hypothesis.

While fanaticism isn’t a precondition for suicide bombings, Berman and Laitin do argue that hybrid religious sects–sects like Hamas that provide public goods and services as well as fight wars–have an advantage in insurgency and suicide bombing.

In their view, religious sects are like “club goods”–they provide something that members value (like religious salvation and community, as well as public services) that is limited to members alone. Also, significant sacrifices are required to join (like years of religious study, or strict behavioral restrictions). These sacrifices screen out the uncommitted, and make the club good more valuable to remaining members.

Such an organization is more effective at insurgency and suicide bombings because it lowers the likelihood that a member will fail to carry out his or her orders. The least committed are screened out ahead of time, and the group can “punish someone who does defect by withholding services.

This is a nice explanation, a nice analysis, and a great paper. I’m still not fully convinced, however, that this is the main logic underlying suicide terrorism.

One of the crucial assumptions in their logic is that it must be costly to the group for the suicide attacker to be captured. But is this always true for a group like Hamas and Hezbollah? Is the motive for the suicide of the attacker really to avoid their capture? Is capture more costly to these organizations than it is for other insurgencies? The logic is plausible but not necessarily true.

Their model also seems to sidestep the million dollar question: why is it ever rational to blow oneself up? The model described by the authors clearly shows how it makes sense for a group to promote suicide tactics. Unless the actual bomber values the afterlife, martyrdom, or the payments to his or her family, then we are back to explanations of psychological manipulation, propaganda, and religious fanaticism (which the authors are trying to avoid).

Suicide attacks seem to be carried against hard targets only when the opponents are of an opposing religion. Why don’t differences in ethnicity provoke the same approach? Think of Basques or South African blacks, who did not resort to terrorism.

What I like about the paper most, however, is their focus on how an understanding of the logic underlying these groups contributes to the counter-insurgency, counter-terrorism, and humanitarian policies of the US. This is precisely why the logic of violence is such an important area of research.