The development of the field of terrorism studies has, in recent years, appeared to outpace the development of actual terrorism. Now may be the era of diminishing marginal returns. One conclusion from English's thoughtful, informed meditation on the state of terrorism research is that there is not a lot new to say (and even here the field could have been spared another disquisition on the problems of terminology). It is not evident that the general lessons for counterterrorism that have come to the fore in dealing with Islamist terrorism are that different from those that emerged from dealing with Northern Ireland (on which English has written extensively). The basic need is to maintain a sense of perspective and understand that although particular campaigns come and go, political violence is a continuing possibility. English argues that governments must accept that the military has a limited role to play when dealing with the violence but that good intelligence will always be necessary.
Another author with an Irish background is Horgan. His topic, asking why terrorists disengage, is a good one, and is far less explored than the question of why they engage in the first place. Unfortunately, as a pilot project for something bigger, this book has a rather interim and tentative feel. After an earnest section on methodology and a decent overview of the current debates over deradicalization, there are eight case studies of individuals, representing only a small sample of the interviews Horgan has conducted, and these are only moderately interesting. It is hard to discern a single pattern of disillusion. What does come across is that whatever terrorists' commitment to an underlying ideology, their actual experience of perpetrating violence affects them in different ways and can lead to disaffection.
The real gem of recent releases is Berman's brilliant analysis of religious terrorism. The value lies not only in what is learned about this form of violence but also in the elegance of the analysis. This is first-rate social science, with a compelling theory, strong evidence, and an accessible style. The conventional explanations for the success of religious terrorist groups point to the nature of the theology and perhaps fanatical cultural predispositions. Berman identifies the need to avoid defection as essential for the survival of these organizations, a weakness that the authorities can often exploit by making irresistible offers to individual members, in the form of either bribes or threats. To understand why defection is less frequent than might be expected, he explores the nature of religious communities that tend to insist on distinctive dress and social codes, encourage religious education even though it limits opportunities for outside advancement, and provide charitable services to their adherents. They use whatever extra revenues they can get to boost these services and distance members from the most likely alternative culture. In most cases, these religious communities have nothing to do with terrorism -- for example, ultra-Orthodox Jews -- but should such groups become inclined to violent strategies, the tight communal bonds help solve the problem of defection. Their loyalty to their communities, and the aid that will go to their families, helps explain the readiness of some to become suicide bombers and also why the nonsuicidal members of terrorist teams stick with their tasks.