Authoritarianism is not a new, untested concept in the American electorate. Since the rise of Nazi Germany, it has been one of the most widely studied ideas in social science. While its causes are still debated, the political behavior of authoritarians is not. Authoritarians obey. They rally to and follow strong leaders. And they respond aggressively to outsiders, especially when they feel threatened. From pledging to ‘make America great again’ by building a wall on the border to promising to close mosques and ban Muslims from visiting the United States, Trump is playing directly to authoritarian inclinations.