Paul Krugman: Why We Fight Wars

A century has passed since the start of World War I, which many people at the time declared was “the war to end all wars.” Unfortunately, wars just kept happening. And with the headlines from Ukraine getting scarier by the day, this seems like a good time to ask why.

Once upon a time wars were fought for fun and profit; when Rome overran Asia Minor or Spain conquered Peru, it was all about the gold and silver. And that kind of thing still happens. In influential research sponsored by the World Bank, the Oxford economist Paul Collier has shown that the best predictor of civil war, which is all too common in poor countries, is the availability of lootable resources
like diamonds. Whatever other reasons rebels cite for their actions seem to be mainly after-the-fact rationalizations. War in the preindustrial world was and still is more like a contest among crime families over who gets to control the rackets than a fight over principles.