What makes terrorists tick?

Not long before the Sept. 11 attacks, Harvard-trained political scientist Louise Richardson gave up the full-time pursuit of her scholarly specialty — the origins of terrorism.

“It was a lot more difficult then than it is now to persuade people of the importance of terrorism, except of course my students, who were always deeply engaged,” she said.

Today, Richardson is busy as the executive dean of the Radcliffe Institute for Advanced Study — and busier than ever as a lecturer on terrorism. She’s one of a small band of academics who specialize in where terrorists come from, why they get support, and how they decide to escalate their politically motivated violence.

The 50-year-old political scientist, teacher, and author grew up in Roman Catholic rural Ireland just as a long civil war boiled over into open violence. That background — including a teenage flirtation with the idea of joining the Irish Republican Army (IRA) — was in part why she set her academic sights on terrorism “long before it was fashionable,” said Richardson.

As for the IRA, she added, “by the time they did try to recruit me, I was older and wiser.”

With her academic specialty now in the limelight, Richardson has made Radcliffe an intellectual crossroads for scholarly debate on terrorism, and what nations should do about it.

For one, she is collaborating with Philip B. Heymann, the James Barr Ames Professor of Law at Harvard Law School, to organize a series of private seminars on the “complicit communities” that terrorists need to survive — and how to reduce the incentives for this critical local support.

The group — academics, writers, and former intelligence experts — started meeting in April, with a daylong discussion of terrorism at a big table in the sunny and serene Radcliffe Gymnasium.

Sitting next to Richardson was forensic psychiatrist and former Central Intelligence Agency case officer Marc Sageman, whose “Leaderless Jihad” (University of Pennsylvania Press, 2008) describes how Muslim youth become radicalized.

By this fall, Richardson’s collection of experts will offer the new occupant of the White House their recommendations.

“The new president, whoever he or she is, is going to have to make a dramatic change — provide a clear message early on that the new administration is different,” she said.

Starting in 2006, Richardson has also used Radcliffe to hold three “expert seminars” on postcolonial wars.

Joining in the private discussions were unlikely groupings of former insurgents, military leaders, and humanitarian aid representatives.

“These are not people who normally talk to one another,” said Richardson, whose experts include former Tamil Tiger fighters and the military officers who fought them. “This is what we try to do at Radcliffe — get people in the room who would not normally be in the room together.”

Helping to organize all this is physician Jennifer Leaning, co-director of the Harvard Humanitarian Initiative and professor of the practice of international health at the Harvard School of Public Health.

The first seminar, in December 2006, brought together experts on postcolonial wars in Algeria, Mozambique, Angola, and Vietnam.

The second, in December 2007, dealt with conflicts in Kenya, Malaya, and Sri Lanka. The third, in May, was on conflicts in the Democratic Republic of the Congo, in the former Rhodesia, and in the violent borderlands of Rwanda and Burundi.

In October, said Richardson, the public will be invited to a “culminating conference” on the origins, conduct, and impact of these wars.

One finding that has emerged so far, Richardson asserts: The longer a conflict goes on, the more reformists are marginalized, and the more ruthless, tough, and intractable the leaders of resistance become. It’s a lesson for the American war in Iraq, she said.

Since the Sept. 11 attacks, Richardson has maintained a breakneck series of globe-spanning speaking engagements and interviews — 60 last year alone, which took her from Singapore and Indonesia to Berlin, Brussels, and Berkeley. (In three weeks last month, she flew three separate times to Europe.)

Shortly after the 2001 attacks — it was still September — Richardson was at Simmons College for a debate on the proper response of nations to terrorist attacks. Her opponent — crisis consultant and State Department veteran L. Paul Bremer — went on to act out his responses to terrorism as head of the Coalition Provisional Authority in post-invasion Iraq.

Said Richardson mildly, “We had very different perspectives.”

Her own views on the best responses to terrorism are outlined in “What Terrorists Want: Understanding the Enemy, Containing the Threat” (Random House, 2006).

Richardson conceived the book as a primer on the complexity of terrorism, which she defines as the deliberate and violent targeting of civilians for political purposes.

Fundamentally, terrorism requires a “lethal cocktail,” she wrote — “a disaffected individual, an enabling community, and a legitimizing ideology.”

And any terrorist wants “three immediate objectives,” according to Richardson, who coined “the three Rs”: revenge, renown, and reaction.

So far, Richardson contended, American response to terrorism — including declaring a global war on fighters without armies or states — has given Islamic terrorists all three outcomes they desire.

Not every attack can be prevented, she said, but democratic governments can temper and control their reactions.

Richardson’s latest book, co-edited with Robert J. Art, is “Democracy and Counterterrorism” (United States Institute of Peace Press, 2007). It outlines 16 case studies of how democracies combated terrorism and won.

According to Richardson, fighting terrorism requires having a defensible and achievable goal — and “eliminating terror” is neither, she said. Fighting terrorism also requires living by democratic principles, knowing your enemy, finding allies, maintaining perspective, and separating terrorists from their communities.

Richardson is a master of context. For one, she said, the idea of terrorism goes back millennia. Its first documented practitioners, Richardson argued, were the Zealots, Jewish nationalists who nearly two thousand years ago opposed Roman rule in Palestine. Since then, said Richardson, religious believers of every stripe — when weaker than their adversaries — have resorted to terrorism.

Along with a steady output of books, book chapters, essays, reviews, and interviews, Richardson has continued to teach — a joyful skill that well before the Sept. 11 attacks had netted her Harvard’s Levenson Memorial Teaching Prize and the Roslyn Abramson Award, both for undergraduate teaching.

In fact, it was an immediately popular junior honors seminar at Harvard College in the early 1990s that inspired Richardson to bring her lifelong interest in terrorism studies into the classroom for the first time.

Since then, she has taught at least one course a year on terrorism, including one every year since Sept. 11, 2001, at Harvard Law School, where she is a lecturer.

Sometimes her teaching takes an informal turn. On the morning of the Sept. 11 attacks, Richardson was at Radcliffe’s Fay House talking with architects about a renovation project. Drew Faust, then Radcliffe dean, walked in with the world-changing news.

For the rest of the day, with a television playing in one corner, Richardson gathered staffers together and answered questions about terrorism and its causes.

“It was helpful,” she said, “to talk rationally.”