• Studies Show: Decapitation Counterproductive  The New York Times' Robert Wright kicks off the discussion, looking at the al-Awlaki decision in light of research by one Jenna Jordan of the University of Chicago. He compares killing terrorists to stop terrorism to "try[ing] to end the personal computer business by killing executives at Apple and Dell"--the industry will persist anyway. But beyond that, he says, Jordan's "work suggests that decapitation doesn't lower the life expectancy of the decapitated groups--and, if anything, may have the opposite effect." In fact, with religious groups (like al Qaeda and the Taliban)
  

The chances that a religious terrorist group will collapse in the wake of a decapitation strategy are 17 percent. Of course, that’s better than zero, but it turns out that the chances of such a group fading away when there’s no decapitation are 33 percent. In other words, killing leaders of a religious terrorist group seems to increase the group's chances of survival from 67 percent to 83 percent.

• Would Be Interesting to See More Studies, says counterinsurgency expert and blogger Andrew Exum. He'd like to see increased sample size and "some research demonstrating the effect of decapitation strategies when paired with broader, more comprehensive counterinsurgency or counter-terror strategies." He points out that Jordan's findings are in keeping with the thoughts of intelligence analyst Matt Frankel, whose arguments include--he writes elsewhere--that so-called "[high value targeting] campaigns do not work in a vaccum. They have to be connected to a broader [counterterrorism] or [counterinsurgency] strategy."

• Hard to Stop These Groups No Matter What, points out Mother Jones's Kevin Drum, looking at the Jordan study's numbers. He also links this discussion back to one Robert Wright started last year, citing research of one Aaron Mannes. Mannes showed, in Drum's words, that "killing the leaders of a religious terrorist group doesn't cause them to collapse but it does cause them to embark on even more deadly attacks."

• Decapitation Success Depends Upon What You're Targeting  Juan Cole at Salon draws a distinction between "social movements" and "organizations." Decapitation, he argues. Al-Qaeda, he thinks, is "more like an organization," and killing leaders there can be helpful. Yet "just killing Pashtun insurgent leaders, whether in Pakistan or in Afghanistan, is unlikely to destroy the Taliban, because they are a movement embedded in an often supportive population."

• Don't Expect Administration to Use This, warns Matt Yglesias at Think Progress: "The first rule of being an American foreign policy practitioner or pundit is something like 'ignore all relevant academic research' so I doubt this will make a ton of difference on the debate."