The outrage over Mitt Romney’s extended off-the-record riff to wealthy donors about the fact that “47 percent of Americans pay no income tax” has shown no sign of dying down. As of now, this looks like the defining moment of his presidential campaign. In lumping together those who have no federal income tax liability with those “who believe the government has a responsibility to care for them,” the former Massachusetts governor gave new life to every crude caricature of conservatives as class warriors for the ultrarich.