Political commentators do a lot of deploring of polarization these days. They write as if this were a new feature of our postmodern age, the result of the divisive effects of social media — but this is not a new problem at all. It worried our Founding Fathers more than any other threat to the Republic they sought to establish. In the Federalist Papers, James Madison warned that “Men of factious tempers, of local prejudices, or of sinister designs, may, by intrigue, by corruption, or by other means, first obtain the suffrages, and then betray the interests, of the people.” We remember George Washington’s injunction against foreign entanglements in his Farewell Address, but who recalls his even more fervent warning of “the baneful effects … of the alternate domination of one faction over another, sharpened by the spirit of revenge, natural to party dissension, which in different ages and countries has perpetrated the most horrid enormities”?