These two books present invaluable and unique contributions to the understanding of terrorism and its outcomes. The strength of both books lies in the refreshing perspectives that they offer. Despite the dramatic proliferation in the studies of terrorism since September 11, 2001, the sociological, social-psychological, and economic dimensions of the phenomenon have not until recently received the theoretical attention given to its political ones. These books help to remedy this defect.

Although both books should become essential readings for students of terrorism, they could not be more different. The Faces of Terrorism offers a comprehensive theoretical attempt to explain the causes, dynamics, and consequences of and policy responses to terrorism. Written by Neil J. Smelser, one of the most influential sociologists of our times, it publishes the results of a study that was sponsored by the U.S. National Academy of Sciences. Terrorism, Economic Development and Political Openness is an edited volume by two World Bank economists, Philip Keefer and Norman Loayza. The majority of its contributors are prominent scholars of political economy. The differences in the books' disciplinary perspectives are paralleled by differences in their structures. The first one progresses from the roots of terrorism to its outcomes, while the second volume begins with chapters on the costs of terrorism and only toward the end moves to a consideration of its complex origins and causes. Yet the main difference between the books regards their authors' angle of vision. While Smelser focuses on broad theoretical questions, and thus offers a bird's-eye view of the phenomenon of terrorism, the contributors to Keefer and Loyaza's focus on more specific questions and employ more quantitative empirical techniques and approaches.

Smelser applies his extensive understanding of human behavior and collective action to the study of terrorism. He uses various sociological concepts and theories, including relative deprivation, political opportunity structure, and his own structural strain theory, in a successful attempt to prove that terrorism is a multicasual social phenomenon, and that as a result it should be studied in a broader context than as sui generis. Though, as stated by the author, the book is academic by nature, I found Smelser's writing style to be clear and engaging. One of the things that made this book even more appealing were the boxes embedded in the various chapters. In these boxes Semlser puts aside the academic jargon and shares with the reader his own views and experiences. I was also impressed by the author's ability to overcome many of the problems that are inherent in the study of terrorism. One example is the exclusion of state terrorism from the discussion. While he acknowledges the importance of this phenomenon, he rightfully chose not to deal with it. I agree with his contention that the outcomes of state terrorism are in most cases more horrific than those of terrorism perpetrated by sub- or suprastate actors. Yet in order to understand the causes and dynamics of the latter on a theoretical level, the former, which is different by nature, should be excluded from this framework and addressed in a different study.

The two chapters of the book that deal with ideologies and personal motivations of terrorists are of particular importance. Smelser analyzes ideology as a social construct. This fits very well into the recent growing understanding that rather than blaming specific ideologies or religions for producing terrorism, we should look into the forces within all ideologies that drive a minority of their adherents to extremism and violence. The analysis of personal motivations adds significantly to the literature. Once again, the author suggests that no single explanation can account for all the individual motivations to engage in terrorism. Thus, he is dismissive neither of psychological explanations that lately have become less fashionable nor of the sociological and economic ones. This, in my opinion, reinforces the importance of carrying out interdisciplinary, rigorous empirical research, which is still largely missing from the research on personal motivations and group processes.

Moving to the response to terrorism, Smelser examines the effects of terrorist attacks at the social level in various scenarios, starting from rare occurrences and ending with a continuous campaign of terror. He then moves on to discuss various modes of response to terrorism, both in the short and long runs, and identifies their advantages and disadvantages. I found his realistic analysis of the costs of various counterterrorism approaches extremely sobering. The book ends with an interesting appendix that deals with the question of the definition of terrorism from a scientific viewpoint. Smelser's observations contribute significantly to current theoretical debates regarding the study of terrorism. Even more significant is the contribution to policymaking. In my opinion the most substantive contribution of the book is its broad theoretical and perhaps even epistemological message—that terrorism is a multifaceted and complex phenomenon that eludes reductive explanations. Though this may be frustrating for policy makers who typically seek easy and quick fixes, if anti-terror policies are to be effective, it is essential that they be derived from the most sophisticated social scientific understandings, and that they should be accordingly nuanced and flexible in applying these understandings.

The goal of the editors of the second volume is to address two important and often neglected economic questions. The first is the economic costs of terrorism and counterterrorism. The second is the various types of connections that exist between economic development and terrorism. The opening chapter by Todd Sandler and Walter Enders brings forward empirical evidence that the costs of terrorism are much higher in small and poor countries than in larger, more affluent ones due to the fact that larger and richer countries are more capable of making policy adaptations and diverting resources in order to help the affected sectors. In a less statistically sophisticated yet very enlightening analysis, Gregory F. Treverton and his collaborators offer a comparative analysis of the economic costs of United States and UK counterterrorism policies. Some of their conclusions are especially interesting and counterintuitive. For example only 1%–2% of the U.S. GDP is devoted to such tasks. Moreover, most of the expenditure on counterterrorism is a result of military operations abroad.

S. Brock Blomberg and Gregory D. Hess's chapter opening the second part of the book reintroduces a sophisticated quantitative method for assessing the influence of economic development on terrorism. They find that crossnational terrorism is positively associated with increasing development. Yet a closer look at the data shows that in developing countries this trend is reversed. As for domestic terrorism, it is actually negatively tied to levels of development. Their second chapter, which looks into the ties between globalization and terrorism, suggests that increasing levels of development, democracy, and openness create a safer environment in countries from which terrorism originates. On the flip side, such improving conditions make the country more likely to become a target for terrorists. Alan Krueger and David D. Laitin offer a slightly different angle. They find that economic indicators, such as GDP and illiteracy, are not good predictors for assessing whether terrorism will originate from a specific country. They conclude that such ties are indirect and are actually mediated by non economic variables, most prominently levels of repression. Nicholas Sambanis takes this critical approach to the impact of development on terrorism even further. He argues that terrorism is a complex phenomenon that can appear in various situations and cannot be explained by a single model. Further, he asserts that levels of income or democracy are unlikely to be of much help in explaining this phenomenon. Yet in cases where terrorism appears as a tactic within the broader context of a civil war, enhanced levels of development can help to diminish it. The next chapter by Laitin and Jacob N. Shapiro focuses less on policy solutions than on methodological and theoretical questions. The authors, who view terrorism as a tactic adopted by rebel groups, argue that in order to offer models for explaining terrorist campaigns, rather than merely measuring the number of terrorist attacks, it is necessary to consider a new dependent variable—the ratio between terrorist attacks and other actions that the rebels take.

Most of the contributors to Keefer and Loayza's volume seem to agree with Smelser that it is impossible to find a single variable or model for predicting, much less explaining, terrorism, a point strongly underscored in Fernanda Llussá and José Tavares's concluding chapter. Indeed, both books together clearly indicate the increasing theoretical and empirical pluralism and sophistication in the field of terrorism studies. For many years confined to the disciplinary boundaries of political science, the study of terrorism is becoming thoroughly interdisciplinary. This should be a welcome development for scholars and policymakers alike.