Noah Smith in Noahpinion:
One name you don’t hear a lot these days is Thomas Piketty. In 2013, the French economist burst into the popular consciousness with the publication of Capital in the Twenty-First Century. The basic thesis was that unless extraordinary forces — war, or massive government action — intervened, capitalism would naturally tend toward greater and greater inequality. That thesis was summarized by the famous and pithy formula “r>g”, meaning that if the rate of return on capital is greater than the growth rate of the economy as a whole, inequality mechanically increases. In Piketty’s telling, only the extraordinary combination of the Great Depression, the New Deal, World War 2, and rapid postwar growth managed to save us from a social collapse due to spiraling inequality in the early 20th century, and now we were back in the danger zone.