Political scientists have documented how the spirited disagreements that used to characterize our political system have turned to rancor and disdain. Democrats and Republicans alike are far more likely today than they were only a few decades ago to say their rivals are not just wrong but stupid, selfish, and close-minded
This statistic is particularly telling: In 1960, only 5 percent of Republicans and 4 percent of Democrats said they would be displeased if their son or daughter married somebody with the opposing party affiliation. In 2010, 49 percent of Republicans said they would be unhappy if their son or daughter married a Democrat, and 33 percent of Democrats said they’d be unhappy if their son or daughter married a Republican
Political sociologist Seymour Martin Lipset puts it this way in his 1959 classic Political Man: "A stable democracy requires the manifestation of conflict or cleavage so that there will be struggle over ruling positions, challenges to parties in power, and shifts of parties in office.” But he added that the system must permit “the peaceful 'play' of power,” and “the adherence by the 'outs' to the decisions made by the ‘ins.’”
If the “ins” fail to recognize the rights of the “outs,” Lipset concluded, “there can be no democracy."
In 1967, Lipset, along with Stein Rokkan, edited a volume entitled Party Systems and Voter Alignments: Cross-National Perspectives, in which they noted that political conflicts come in many varieties. They conceptualized them along a spectrum from most tractable — that is to say, workable and manageable — to least tractable.
At the tractable end of the spectrum, they placed a politics of pure economic materialism: They include conflicts over allocation of resources — disputes between producers and buyers, workers and employers, tenants and owners, and so on. These “can be solved through rational bargaining and the establishment of universalistic rules of allocation.”
At the intractable end are what Lipset and Rokkan call “Ideological oppositions.” These are all-consuming, 24-hour disputes “incompatible with other ties within the community.” In this kind of conflict, each side strives to “protect the movement against impurities and the seeds of compromise."
This is the kind of politics that leads to democratic breakdown and violence.