Piketty's Three Big Mistakes

Matt Rognlie is a fun guy and a very smart guy. An economics doctoral student at Massachusetts Institute of Technology, Rognlie had a blog, but ditched it in favor of writing long comments and e-mails to bloggers (including yours truly). As proof that blogs can be an important part of the research process, Rognlie turned a blog comment into the most biting critique of Thomas Piketty yet produced.

Piketty, remember, is the French economist who became a celebrity for his work on inequality. In his blockbuster book, "Capital in the Twenty-First Century," he asserts that the rate at which capital owners’ wealth increases is almost always larger than the rate of economic growth. If that’s true, it means that the rich get richer, and wealth inequality never stops increasing.