That’s the title of a 2016 meta-analysis by Michal Bauer, Christopher Blattman, Julie Chytilova, Joseph Henrich, Edward Miguel, and Tamar Mitts. It’s a fascinating and contrarian view on the long-term consequences of violence.
The short answer in the paper is that yes, it does. That’s the counter-intuitive angle that the paper is trying to evoke.
But almost certainly the more precise answer based on the weight of their research is, “war fosters cooperation among insiders, but not much cooperation, and perhaps even some hostility, toward outsiders.” This more nuanced answer is much less counter-intuitive than the title of the paper might suggest.
Think of the way that countries rally together during war or after a terrorist attack. When one’s survival is threatened, the instinct is to cooperate and work together to fend off an outside threat. The “rally around the flag” effect is real.
According to research by Bauer, Cassar, Chytilova, and Henrich (2014) in war-torn Sierra Leone, victims of violence were much less selfish and more inequality averse toward in-group members than those who had never been exposed to war. But there were no comparable effects of cooperation and unselfishness toward outsiders. Further, additional research by Cecchi, Leueld, Voor, and van der Waal (2015) on soccer players in Sierra Leone showed that victims of war violence behaved more altruistically toward their teammates but were also more likely to get yellow or red cards than those who were not victims of violence.
In the United States, the generation that fought in World War II is often referred to as “The Greatest Generation.” What made them so great?
That generation, more so than prior or subsequent generations of Americans, faced a real existential threat. They came together and overcame that threat, and that effort brought them closer together, creating a social cohesion that other generations do not possess.
To the extent that our country is particularly polarized now, perhaps one can view the lack of a serious external rival as a contributing factor in that polarization. Without external rivals to force us to direct our attention elsewhere, we increasingly direct our negative energy at our internal rivals.