For a decade, foreign policy circles have treated war between the United States and China as something close to destiny. The theory has a fancy, fashionable name borrowed from ancient Greece: the “Thucydides Trap” – the idea that a rising power and an established one are fated to collide, the way two articulated lorries merging into a single lane rarely ends well. The term is widely used in commentaries on US-China relations. Frictions get written off as “inevitable” regardless of what actually...