Science reports: To beat your enemies, you must understand them intimately. And so anthropologist Scott Atran and his colleagues have spent the last 2 years interviewing Islamic State group fighters and their opponents on the front lines. For a study published yesterday in Nature Human Behavior, Atran, director of research at Artis International, a research institute based in Scottsdale, Arizona, and his research team personally talked with extremists in the field, whom they’d reached through local leaders. They also conducted online surveys with thousands of Spanish citizens in order to include a more pacific population. Science spoke with Atran, who also holds positions at the University of Michigan in Ann Arbor, the University of Oxford in the United Kingdom, and France’s CNRS in Paris, about his work. This interview has been edited for brevity and clarity.

Q: What makes someone willing to die fighting for a cause?

A: Well, lots of things, but what best predicted willingness to die on the battlefront was both devotion to a tight-knit group of comrades—fusion with them—and commitment to sacred values. But the values actually trumped the group, which may be the first time that was shown. Because most of the military sociology and psychology, at least since World War II, has said that will to fight is based on camaraderie and fighting for your buddies.

In September 2014, [then-President Barack] Obama’s national security director said the greatest mistake the U.S. made in Iraq was underestimating ISIS’s will to fight, and he said it was similar in Vietnam. And then he said will to fight is an imponderable, which is why we undertook this study.

Q: What are sacred values?

A: They are moral values. We’ve shown in lots of different contexts that sacred values are immune or resistant to material trade-offs. You wouldn’t sell your children or sell out your country or your religion for all the money in China. Another aspect is that they generate actions because they’re the right thing to do, so you’re not really worried about risks or rewards or cost or consequences. [Continue reading…]