Editor's note (11/16/15): Following the terrorist attacks in Paris on November 13, Scientific American is republishing the following article, which originally ran after the attack on Charlie Hebdo, a Parisian newspaper, in January 2015.

For years, I've been getting emails from people who praise my brilliant research on terrorism and then ask me tough questions about the topic. I'm forced to reply: "Sorry, I'm John Horgan the American science writer. I occasionally write about terrorism, but you have mistaken me for John Horgan the Irish psychologist and terrorism expert." I wish I could take credit for the work of the other John Horgan (who as far as I know is unrelated to me). For more than 15 years, he has carried out extensive interviews with former militants to understand why they turn to and away from terrorism. He has written half a dozen books on terrorism and has consulted for the FBI and other agencies. He was born in Ireland and received his doctorate from University College, Cork, and now directs the Center for Terrorism & Security Studies at the University of Massachusetts, Lowell. (See his website here.) I've been brooding over terrorism even more than usual lately because of terror attacks in Europe and the rise of ISIS. So I emailed Horgan and asked if he thought it would be too "gimmicky" for us to do a Q&A. "I’m all for gimmicky," he replied, "if it allows us to do something informative." Our exchange follows:

"Psychology has tremendous potential both to shape our understanding of terrorism as well as offering us the basis for a strategic framework aimed at reducing terrorist behavior." Psychologist John Horgan

Q: Why did you devote yourself to studying terrorism?

A: Initially, I just fell into it by accident. I was taking a social psychology class at University College, Cork one day and the Professor (Max Taylor, a well known terrorism expert) had just finished teaching us about the Milgram experiments on obedience to an authority. The idea that extreme behavior can often develop from mundane beginnings was the most profound thing I had ever heard. In the next class, Professor Taylor went on to tell us about how the same dynamics worked inside terrorist groups. I was hooked.

Q: How do you define terrorism?

A: The use, or threat of use of violence by non-state groups to achieve political change, and in doing so, targeting non-combatant civilians as its immediate victims.

Q: Some critics, namely Noam Chomsky, accuse the U.S. of terrorism. Comment?

A: Many if not most governments at some point engage in acts that are similar in design and outcome to what we call ‘terrorism’. When states do it, and when it is known they do it, the language changes to something like “state-sponsored terrorism” or even “war crime”. Terrorism as a label is typically reserved for non-state groups. I don’t have any problem with people who abhor that label, but it is something we are stuck with, so we can at least use it consistently. I guess what I do is focus on terrorism by non-state actors. When I tell people I study terrorism, they almost always say, “But what about the actions of this government or that government?” Well there are people who study that too! We cannot fully understand terrorist behavior without studying the behavior of states who claim to counter it – after all, both sides often use the actions of the other to claim legitimacy for what they do, as well as to mobilize their respective audiences into action.

Q: Are there any especially insidious misconceptions about terrorists?

A: There are way too many to list here. An issue I find problematic right now is the idea that to prevent terrorism, we have to first prevent radicalization. It’s an assumption that seems credible, and few would argue against it, but I’m not yet convinced of its scientific validity. There are far more people who hold "radical" views than will ever become involved in terrorism, and there are plenty of terrorists (who are already small in number – a point we tend to forget) who don’t initially hold radical views but drift into terrorism regardless. In fact, more and more evidence suggests that quite a few terrorists acquire their radical views through ideological training only after they become involved with a recruiter or a group. We don’t know nearly enough about the temporal sequencing of this process, yet I never cease to be amazed by how quickly policymakers are to embrace what seems to be an unending series of dueling metaphors that substitute for serious analysis and research.

Q: Are any psychological paradigms—psychoanalysis, evolutionary psychology, behaviorism, etc.—useful for understanding terrorism?

A: I am a behavioral psychologist at heart, and believe we have the conceptual tools at our disposal to develop a science of terrorist behavior, but psychology as a discipline has failed to embrace the study of terrorism. Psychoanalytic explanations dominated in the 1970s and 80s, and we’re seeing some really innovative thinking both from evolutionary psychology but also industrial/organizational psychology in the areas of organizational behavior, creativity, how and why people leave organizations etc. We have a long way to go, but there is some really neat research being done right now by a tiny handful of psychologists. If we could do more to encourage the study of terrorism by psychologists at the graduate level, we’d be in far better shape in 10 years from now instead of asking the same tired old questions (and maybe giving the same tired old answers) every time a crisis unfolds.

Q: What are the major reasons why people turn to terrorism, and especially suicidal terrorism?

A: It’s typically a combination of big issues and little ones, or what some call "push and pull" factors. The bigger issues include alienation, shared anger or outrage (e.g. at some foreign policy), frustration, disillusionment, a sense of victimization by the actions, or in the case of Syria, inactions, of others. The littler issues, the "lures" include the perceived benefits of turning – e.g. adventure, excitement, camaraderie, a sense of belonging, being part of something far bigger etc. The key to understanding is not just to ask why people turn but how they turn, and what strategies recruiters use in that process. Effective recruiters will use whatever tools in their arsenal to pull someone in, whether it is convincing them of their duty to go fight in defense of others, to convincing them that involvement offers them a way out of the humiliation and victimization the recruiter will remind the young person they are otherwise destined to face at home. Radicalization, and how it relates to recruitment (and how we respond to it) is a constantly changing system. Why someone joins today is different to why someone might have joined even the same group three years ago. Don’t expect easy answers. Even repentant terrorists willing to speak about their experiences don’t necessarily have clear answers. A lesson I’ve learned from trying (and failing) to answer that question over the years is that we need a better way of both thinking and talking about motivation.

Q: You have written about "disengagement" from terrorism. How can people be encouraged to turn away from terrorism?

A: I was struck by how rife disillusionment is inside terror groups. The idealism that helps draw someone into terrorism often conflicts with the reality as experienced by the newly minted recruit. Entrapment (in a psychological sense) develops quickly and recruits have to cope with that disillusionment one way or another. You acquiesce to it and move on, maybe by embracing ideological content or seeking comfort in the camaraderie. Or you struggle with and try to conceal it until you can get out. Some terrorists report being disillusioned long before they have been able to disengage from terrorism. They report a sense of suffocation – being unable to leave for fear of retaliation (either by the terrorists or by the State) and being equally afraid of their disillusionment being detected by those close to them in the movement. I think we need to do a better job of providing "off-ramps" not just for people who are on the road to terrorism in the first place, but also to those who have gotten themselves in a jam and want to get out before it’s too late. Some see that as a soft option. I see it as reducing the nature and extent of the problem. We certainly need to do a far better job of showcasing accounts of repentant former terrorists who are in an ideal position to credibly undermine the allure of involvement in the first place.

Q: Is there anything about Islam that makes adherents especially prone to terrorism?

A: Just like talking about "terrorism," it has become impossible to talk about the relationship between Islam and terrorism without causing great offense to some. Debate is so polarized now between those who say that we if we want to understand terrorism, Islam is "everything," and those who say that Islam is completely irrelevant. Both positions are incorrect. I certainly think the role of Islam, and religious ideology more generally, is vastly overstated as a mobilizing agent for involvement in political violence. I believe it is far more relevant in terms of sustaining commitment and continued engagement with a group. Islamic content is used both as a defense of activity as well as a justification for certain kinds of tactics. This is not unique to Islam, however, and I think any "believer" can take great comfort from religious precepts especially if they are struggling to justify to themselves (as well as others) what they have now gotten themselves into. It’s the uncritical embracing of religious ideology that is often associated with terrorism. This is why I think converts appear especially susceptible to terrorist recruiters. They don’t have the deeper religious knowledge that could easily rebut many of the clichéd arguments used by recruiters attempting to inspire young Muslims to mobilize in the first place.

Q: How can we reduce the probability of attacks like the Charlie Hebdo massacre?

Q: This is a tough question to answer. There will be the inevitable talk of preventing radicalization, of doing better job to integrate Muslims and so on. Yet success in either domain will never prevent terrorism from happening. We don’t seem to be capable of realizing that despite a grossly inflated sense of the threat, terrorism is neither an existential problem nor is it something that can be "defeated." Terrorist events remain rare. The bigger question for me is the worrying sense of how poor our societal resilience is, often in the wake of such attacks. There are other, successful examples of countries that have faced horrific acts of violence (e.g. Norway, after the Anders Breivik attack) and made a fundamental choice not to alter their way of life. Some kinds of terrorist attacks (e.g. lone wolf attacks) may be more detectable than people realize, and though the Charlie Hebdo attackers may well be connected to a broader network, I think most people aren’t willing to concede that it’s not actually possible to detect and prevent all terrorist attacks.

Q: The political scientist John Mueller has argued that the U.S. overreacted to the 9/11 attacks. Comment?

A: I agree.

Q: If President Obama asked for your advice on fighting terrorism, what would you tell him? What should he do about ISIS?

A: The President is not short of advice on this matter. What nobody will tell him is that we need longer-term investment so as to avoid frantic and rash policymaking every time a crisis unfolds. We need a Manhattan Project for understanding terrorist behavior, a sustainable investment in more psychological research. I know - of course I would say that - but I’m serious. This is the only thing that will move us beyond the "folk psychology" explanations we see of this phenomenon. Psychology has tremendous potential both to shape our understanding of terrorism as well as offering us the basis for a strategic framework aimed at reducing terrorist behavior. Psychological concepts are increasingly appropriated by other disciplines, notably political science, without any clear sense of either context or limitation. And yet, whenever there is a crisis, the questions that are at the top of the list relate to psychology – why and how does someone become a terrorist and what, if anything, can we do to prevent it?

Q: Will the world ever be free of terrorism?

A: Not until it becomes an ineffective and unattractive strategy for groups who bank on the predictability of our responses to their actions. For that to happen, it depends in part on States holding the moral high ground, formulating responses based on evidence, and not falling into the traps that terrorist groups are so clever at setting for States. So, in other words, no.

Photo: Meghan Moore