The richer and more market-oriented societies have become, the nicer people have behaved. Think of the Dutch after 1600, the Swedes after 1800, the Japanese after 1945, the Germans likewise, the Chinese after 1978. The long peace of the nineteenth century coincided with the growth of free trade. The paroxysm of violence that convulsed the world in the first half of the twentieth century coincided with protectionism.
