An economist, Tyler Cowen, writes in the New York Times:

The continuing slowness of economic growth in high-income economies has prompted soul-searching among economists. They have looked to weak demand, rising inequality, Chinese competition, over-regulation, inadequate infrastructure and an exhaustion of new technological ideas as possible culprits.

An additional explanation of slow growth is now receiving attention, however. It is the persistence and expectation of peace. The world just hasn’t had that much warfare lately, at least not by historical standards.

What is all of this really about? Once again Thomas Piketty. Economists do not know how to get around his book Capital in the 21st Century. What Piketty points out is that the major wars in the 20th century were so destructive that they destabilized the capitalist order, which tends to benefit those whose income is derived from capital assets rather than wages. After the Second World War, those with capital lost some ground to wage earners (the Golden Age of Capitalism). So, with Piketty we get a new and striking possibility: It's not war itself that can bring about economic recovery; but instead any shock that's strong enough to shake some cash loose from where it is currently concentrated and accumulating, at the top parts of our society. What the shock provides is the opportunity for a government to tax the rich. This is the message that has upset so many American economists: taxes really matter.

As for Tyler Cowen, we only get something that George Orson Welles said in 25 seconds a long time ago: