The issue of income inequality has been driving the intellectual, political, and policy debate on the Left and within the Democratic party.

It’s been a strain through President Obama’s rhetoric; part of the rise of populist Sen. Elizabeth Warren, D-Mass.; the explanation for the surprising success of Capital in the Twenty-First Century, the treatise of French economist Thomas Piketty; and the underlying justification for the push for higher taxes on the wealthy and increased minimum wage.