What Iran teaches us about why wars start

Why do countries fight wars that are almost always economically disastrous for both sides? That is the central question economist and political scientist Chris Blattman of the University of Chicago has spent his career studying. On a recent episode of The Indicator from Planet Money, Blattman walked through the five main reasons he has identified — and explained why, despite the headlines, full-scale war is actually the rare exception, not the rule.

Blattman’s interest in the subject began by accident, when he followed a humanitarian worker into a war zone in Northern Uganda. That trip led to a dissertation, several academic papers, and eventually a marriage. His research, much of it conducted with his wife Jeannie Annan, has focused on reintegrating child soldiers and helping women in war-affected areas. What he found confirms something many people suspect: war almost never makes anyone better off. According to Moody’s, the 2025 war with Iran cost the United States at least $132 billion — about $490 for every American adult — and resulted in the deaths of 13 U.S. service members and more than 3,400 Iranians. “There are circumstances where victory and some amount of luck makes you better off after the fact,” Blattman said. “Most of the time that’s not true.”

War is the exception, not the rule