Rising economic inequality in the United States has been a major animating force on both the political left and the right.

Whether it is Bernie Sanders promising to rebuild blue-collar communities or Donald Trump pledging to ‘make America great again,’ today’s political platforms often revolve around a return to the perceived ‘normal’ of a vibrant middle class and more equitable distribution of wealth that America experienced in the 1950s, 60s and 70s.

Yet with a broader look at history, it’s clear that period of falling inequality was the exception, and that today’s increasing inequality is more a return to the norm. And when inequality did fall throughout history, Stanford University Professor Walter Scheidel argues in a new book, it tended to do so for very unpleasant reasons.

In ‘The Great Leveller: Violence and the History of Inequality from the Stone Age to the Twenty-First Century,’ Scheidel examines societies from ancient history to the present. He finds that most societies gradually grew more unequal over time, and where those inequalities were levelled out, they were almost always done so by violent forces — war, revolution or plague. The work contains some shocking lessons about the nature of inequality and what that might mean for our future.

Q. How does inequality today compare with history? When have we seen inequality peak, and when has it fallen?

A. If you look over hundreds or thousands of years, you see a pattern of rising and falling inequality. But for most of history, inequality was either rising or stable at high levels. It’s rare for inequality to fall significantly. In that respect, the world we live in is a typical environment, in which inequality is rising or has reached very high levels in many countries.

Q. We saw an unusually large drop in inequality during World War I and World War II. Has that shaped people’s perceptions of what inequality should look like?

A. It has. The post-war period, the 50s, 60s and 70s, has become the reference point. In that period, economic growth was strong, the middle class was expanding, and inequality was low by current standards. But since the 1980s, growth has slowed, and what growth we have disproportionately benefits the famous one per cent, at the very top at the income distribution.

That marks a real change from the post-war period, and that is understandably perceived as undesirable. But if you look at history more broadly, it’s the post-war period that was anomalous.

Q. Your book discusses four factors that have flattened inequality through history. The first one is ‘mass mobilisation warfare.’ You say that not all wars lead to more equality. What is it about this type of war that does?

A. History has been full of wars, but most don’t systematically equalise the distribution of income and wealth. It’s really a phenomenon of the first half of the 20th Century. For the first time you have wars on a really large scale, where a large percentage of the adult male population is conscripted, and civilian men and women alike are mobilised for the war effort.

For the first time in history, industrial capacity and the nation state make it possible for government to reshape economic outcomes in a time of crisis. To raise funds for the war, the government raises taxes to extremely high levels — over 90pc on the highest earners in the US in the 1940s. In many countries, the war causes massive physical destruction of capital, housing stock and factories.

The rich lose a great deal. At the same time, unskilled workers are better off, because there is more demand for their labour, and conscription leads to full employment, which drives up wages. A number of things come together in just the right way to greatly compress inequality in the US, Europe, Japan and other countries involved in these conflicts.

Q. What are the other three great levellers?

A. The second factor I discuss in the book is Communist revolutions, which grow out of WWI and WWII in the case of Russia and China. Communist revolutionaries expropriate and nationalise all assets, land and industry. They create a planned economy with set wages and prices. As a result, very little inequality is left in their systems.

But these are very violent events. Tens of millions of people lose their lives. And greater equality only lasts as long as the regimes are in place. Once the Soviet Union collapses, inequality doubles within just a few years in Russia. When China liberalises its economy in the 1980s, it sees huge economic growth, but inequality rises as well.

The last two forces were more common in pre-modern history. One is the collapse of the state, for example Mayan civilisation, or the fall of the Roman Empire. In these cases, if the earlier state created or reinforced inequality, then its dismantling has the opposite effect. The ruling class is undermined or in extreme cases disappears entirely.

The last is severe epidemics like the Black Death, the plague in late medieval Europe. When massive pandemics kill a large percentage of the population, there is as much land and capital as before but there are fewer workers, and that increases demand for labour and raises wages. The poor are less poor and the rich are less rich, and the gap between them narrows significantly

Q. Every one of these major compressions was driven by something very violent or unpleasant. You argue that peaceful methods of levelling equality, like democracy, education and land reform, aren’t nearly as effective, right?

A. That’s true. It’s not to say that these things don’t have an effect. If we didn’t have a form of social democracy, redistributive measures and mass education in the US today, conditions would be much worse. But if you’re looking for a sizeable reduction in inequality, history indicates that peaceful measures by themselves are not going to make that much of a difference. There are no major episodes of levelling in history that are not associated with some kind of violent disruption.

— The Washington Post Service

Published in Dawn, Business & Finance weekly, April 24th, 2017