As Democrats wonder how the United States overwhelmingly chose to elect a convicted felon to the nation’s highest office, one answer may be found in the words of a Republican-appointed former Supreme Court justice. On Wednesday, MSNBC columnist Steve Benen recalled how Associate Justice David Souter — who was appointed by President George H.W. Bush in 1990 — warned Americans in 2012 that authoritarianism was just around the corner. Souter predicted that, paradoxically, American democracy could end up being its undoing if a majority of voters in an election collectively decide to end it. “I thi…