What makes Thomas Piketty so sure he can save the world?

The French economist, statistician and polymath Thomas Piketty sprang to fame in 2013 with a daunting tome, Capital in the Twenty- First Century. In it he documented a ‘fundamental force of divergence’ in the capitalist system, which he represented by the equation r>g — the tendency for returns to capital to grow faster than national income, and therefore for wealth to concentrate in fewer and fewer hands. This tendency was reversed between 1914 and 1980 by the impact of two world wars, the Great Depression, social democracy and the trade unions, but it has since reasserted itself, restoring levels of inequality last seen 100 years ago. In his new blockbuster,