In his inaugural address Wednesday, incoming New York Mayor Bill de Blasio tried to establish an intellectual pedigree for his focus on economic inequality. He invoked Bill Clinton, Hillary Clinton, Franklin Roosevelt, Eleanor Roosevelt, Al Smith, Frances Perkins, Fiorello La Guardia, Jacob Riis, David Dinkins, Mario Cuomo, and Harry Belafonte. It reminded me of when Democrats, eager to prove their national-security bona fides, tell audiences they hail from the party of Roosevelt, Truman, and Kennedy. As if there wasn’t some other Democrat after Kennedy who dabbled at war and peace, some guy from Texas. De Blasio’s speech was a bit...