French economist Thomas Piketty caused a sensation in early 2014 with his book on a simple, brutal formula explaining economic inequality: r is greater than g (meaning that return on capital is generally higher than economic growth). Here, he talks through the massive data set that led him to conclude: Economic inequality is not new, but it is getting worse, with radical possible impacts. In this TED, which took place in Berlin, Piketty argues that wealth inequality is always a lot higher than income inequality. He calls for progressive income taxation to redistribute wealth.