States are still built on stratification, on hierarchy, on concentration of power. Even if they are formally democracies, it doesn't seem to make an enormous difference, because even in democracies there are ways for the rich to exercise disproportionate influence on the political process, as we see in the United States today. That means that even in attenuated form, states tend to preserve, if not in some cases actively promote inequality.

Historian Walter Scheidel traces the long twin histories of economic inequality and violence throughout human history - as a cycle of rising wealth disparity and brutal, leveling shocks have followed us since the dawn of agrarian civilization - and explains why peaceful solutions to today's inequality won't be found in the past, but must be built in the future.

Walter is the author of The Great Leveler: Violence and the History of Inequality from the Stone Age to the Twenty-First Century from Princeton University Press.