An eye for an eye

Revenge cuts both ways in the Israeli-Palestinian conflict. Scientists of the University of Zurich, the Massachusetts Institute of Technology, and Tel Aviv and Quinnipiaq Universities show that attacks by either side lead to violent retaliation from the other. Both Israelis and Palestinians may underestimate their own role in perpetuating the conflict.

A team of scientists from the University of Zurich, the Massachusetts Institute of Technology, and Tel Aviv and Quinnipiaq Universities have found that attacks by both Israel and Palestinians lead to violent retaliation from the other side. This finding challenges claims by both Israelis and Palestinians that they confronted with a fundamentally hostile and implacable foe, suggesting instead that part of the violence of each side is a direct reaction to previous attacks by the other party.

The team analyzed a large dataset of killings and rocket attacks in the Second Intifada between Israel and Palestine, spanning the years 2000-2008, using a statistical method called Vector Autoregression. "This technique allows us to study the effect of a single additional attack from one side on future attacks by the other side," says lead author Johannes Haushofer, a neurobiologist and economist at the University of Zurich. "We find that when one side attacks the other, they directly inflict a certain additional number of fatalities or rocket attacks on their own people, because they can be nearly certain that the other side will retaliate. For example, when Israeli forces kill 5 Palestinians, they automatically increase the probability that Israelis will die from Palestinian attacks on the following day by 50%."

The study, published in Proceedings of the National Academy of Sciences this week, overturns earlier findings which had suggested that only Palestinian attacks lead to retaliation, while Israeli attacks did not. "The previous evidence suggested that Israeli attacks were often responses to Palestinian aggression, whereas this did not appear to be true for Palestinian attacks," says Anat Biletzki, a professor of philosophy at Tel Aviv and Quinnipiaq Universities, and former head of BT'selem, an Israeli human rights organization that collects the data that were used in the study. "This implied that the conflict was one-sided, with Palestinians attacking Israel, and the Israeli army merely responding to this aggression. Our findings suggest that the situation is more balanced than that."

The scientists hope that this insight will lead to a better understanding of the forces that perpetuate the conflict. "Psychologists have long known that people tend to understand their own behavior in terms of the external situation they find themselves in, but another person's behavior in terms of that person's inherent character," says Nancy Kanwisher, a professor of neuroscience at the Massachusetts Institute of Technology and the senior author of the study. "This cognitive bias may exacerbate blind spots on both sides of the conflict and tend to think of themselves as victims who merely respond to external violence, without appreciating their own causal role in provoking those acts of violence."