ANN ARBOR—Although Islamic State fighters are often undermanned and undergunned, they prove difficult enemies to fight.

Researchers from the University of Michigan and Artis International show that the tenacity of these fighters—and those who oppose them—comes from a willingness to fight and die due to a commitment to sacred values, a readiness to renounce kin for those values, and a belief in the spiritual strength of their own group compared with the enemy.

The findings, reported in a study published in Nature Human Behaviour this week, help us understand what motivates individuals to join the battlefield. The research was led by Scott Atran, U-M professor of psychology, and Ángel Gómez, associate professor of social psychology at the research institute Artis International.

When ISIS greatly expanded its control over swaths of Iraq in summer 2014, the terror group’s battlefield advances took many by surprise, suggesting a will to fight that was not initially shared by the Iraqi army, the researchers say.

A proposed reason for the Islamic State’s will to fight is that their fighters act as “devoted actors.” They are willing to engage in costly sacrifices and extreme actions when motivated to protect non-negotiable sacred values—values that people refuse to trade off for material or monetary compensation.

“Although most analyses focus on relative material prowess among conflicting parties, ever since World War II, insurgent groups have in general prevailed with as little as 10 times less firepower and manpower than state forces,” the authors write. “One plausible reason resides in the motivations of combatants: when group interests become sacred and non-negotiable, spiritual considerations trump material ones.”

Atran—who is an adjunct research scientist in the Research Center for Group Dynamics, part of the U-M Institute for Social Research, and research professor at the Gerald R. Ford School of Public Policy—Gómez and colleagues now provide new evidence that the “devoted actor” framework can be used to understand the will to fight.

They use a combination of field interviews with frontline fighters in northern Iraq from February-March 2015, including captured ISIS fighters; a quantitative field study conducted from February-March 2016 among 56 Kurdish Peshmerga forces, Iraqi Army Kurds and Arab Sunni militia fighting in opposition to ISIS; and a series of large-scale online studies with over 6,000 Spanish participants.

The researchers identify a common association between the willingness to make costly sacrifices such as their own lives or the well-being of kin, a commitment to sacred values and the perception that one’s own group is spiritually stronger than the enemy.

Although the investigation suggests that commitments to abstract causes—such as “Kurdeity,” a sense of commitment to Kurdish language, heritage and land—informs the will to fight, the authors note that an equally important question for further research is why some groups are better able than others to inspire loyalty to abstract causes.

In an accompanying News & Views, John Horgan writes: “To say that studying frontline fighters is “challenging” (as the authors do) is an understatement. Yet, what makes this study all the more remarkable is its seamless interweaving of ethnographic, experimental and interview-based research both informed and challenged by a rich, interdisciplinary theoretical framework.”

Partial funding support came from the Minerva Program of the U.S. Department of Defense, as well as the Office of Naval Research, U.S. National Science Foundation and the Spanish government.

More information:

• Study: The devoted actor’s will to fight and the spiritual dimension of human conflict
• Scott Atran