The Rosetta Stone that explains this tribal divide is Columbia historian Richard Hofstadter’s classic 1964 essay, “The Paranoid Style in American Politics.” Hofstadter’s piece for Harper’s may be unfamiliar to many now, but each writer at the opening of this column knows by rote what Hofstadter’s essay taught generations of young, left-wing intellectuals about conservatism and the right…

Frank Rich, Oct 17: “Don’t expect the extremism and violence in our politics to subside magically after Election Day—no matter what the results. If Tea Party candidates triumph, they’ll be emboldened. If they lose, the anger and bitterness will grow.”

Robert F. Kennedy Jr., Tuesday in the Huffington Post: “Jack’s death forced a national bout of self-examination. In 1964, Americans repudiated the forces of right-wing hatred and violence with an historic landslide in the presidential election between LBJ and Goldwater. For a while, the advocates of right-wing extremism receded from the public forum. Now they have returned with a vengeance—to the broadcast media and to prominent positions in the political landscape.”

This isn’t just political calculation. It is foundational belief.