A battle is raging in terrorism studies. Proponents of the "strategic model" claim that rational people participate in terrorist groups mainly for the political return. Proponents of the "natural systems model" claim that rational people participate in terrorist groups mainly for some form of social gain. The first model argues that terrorists attack civilians for the collective benefit of coercing political concessions, whereas the natural systems model claims that individuals engage in terrorism for the personal, selective benefit of participating in an exciting, tight-knit, social group. Although this debate is spearheaded by academics, it is hardly academic: The question of terrorist motives is fundamental to counterterrorism because one cannot expect to cure a malady without understanding its underlying cause.
Cronin, professor of strategy at the U.S. National War College, does not explicitly align herself with either school of thought, but How Terrorism Ends suggests that social calculations are more determinative than political ones. Her analysis of how terrorism ends indicates that it is seldom due to rational, political considerations. Cronin finds, for example, that negotiating with terrorists "very rarely" works since most "terrorist groups choose not to negotiate at all." This aversion to compromise results because "organizational survival overshadows the [stated] cause." The logic is clear but sadly familiar: "If violence is part of the identity or livelihood of participants themselves, then the likelihood of negotiations resolving a conflict is miniscule." The Oslo accords are illustrative: By embracing them, Palestinian terrorists of all persuasions would have unquestionably advanced their stated territorial aims. But groups such as Hamas and Palestinian Islamic Jihad instead ramped up their violence, helping to derail the peace process in order to ensure their organizational survival.
In fact, Cronin notes that what usually brings terrorists to the negotiating table are generally threats to the organization itself rather than to its putative political purpose. She finds that terrorist groups rarely abandon the armed struggle due to achieving their official political goals. This conclusion is expected given the fact that terrorist groups virtually never attain their given political aims, a point underscored in this reviewer's 2006 study in International Security, which compared the abysmal success rate of terrorist campaigns to other forms of protest. Her case studies do, however, bolster the thesis that terrorism is inherently politically counterproductive by hardening governments and discouraging them from making concessions. She sensibly focuses on the handful of terrorist groups in modern history that achieved their policy demands such as the African National Congress and shows that they did so "despite the use of violence against innocent civilians [rather] than because of it." The author is quick to point out that this does not mean terrorism accomplishes nothing at all; as previous studies have shown, terrorist acts can undercut the organization's professed political agenda while simultaneously boosting membership, morale, and cohesion.
So how then does terrorism end? By provoking government repression, its perpetrators have occasionally been stamped out. In fact, Cronin observes that "it is difficult to find cases" where governments did not use repressive measures, digging in their political heels. This does not mean that she endorses a policy of outright repression, however, since this response risks backfiring by turning the local population against the government and ultimately invigorating the terrorist group. A more frequent way for terrorism to end is by alienating potential supporters. She provides numerous examples of terrorist groups that "imploded" due to their lack of appeal to fresh recruits, infighting between organization members, and especially, backlash against the gory violence itself, which she believes is "the most common" way for these organizations to go out of the terrorism business. One example occurred in August 1998 when the Real Irish Republican Army splinter-group spurred a local backlash against it by killing twenty-nine noncombatants in Omagh, Northern Ireland. Similarly, the November 2005 Islamist terror attacks in Amman, Jordan, killed sixty innocent people but dramatically eroded local support for al-Qaeda and its affiliates throughout the country. Finally, Cronin finds that terrorist groups sometimes abandon the armed struggle but remain intact for patently apolitical reasons. A typical reorienting pathway is the transition to purely criminal behavior exemplified in the Abu Sayyaf Group, a Philippines-based al-Qaeda affiliate.
Cronin has written an important book on how terrorism ends. Her analysis is equally illuminating for its insights into why people engage in terrorism in the first place. The evidence is growing that these two areas of study may actually lead to the same conclusions. If so, serious implications for counterterrorism policy should flow from the recognition that social factors tend to trump political ones in the making and unmaking of terrorists.
Max Abrahms is a postdoctoral fellow in the Dickey Center for International Understanding at Dartmouth College, a postdoctoral fellow on the Empirical Studies of Conflict project sponsored by Princeton University, and lectures on terrorism at Johns Hopkins University.
 On the debate in terrorism studies between the strategic model and the natural systems model, see Max Abrahms, "What Terrorists Really Want: Terrorist Motives and Counterterrorism Strategy," International Security, Spring 2008, pp. 78-105.
 Max Abrahms, "Why Terrorism Does Not Work," International Security, Fall 2006, pp. 42-78.
 Mia Bloom, Dying to Kill: The Allure of Suicide Terrorism (New York: Columbia, 2005); Marc Sageman, Understanding Terror Networks (Philadelphia: University of Pennsylvania Press, 2004).