NYTimes

Both parties, though, change shape to fit the zero-sum contours of the moment. Progressives emphasize compassion less and redistribution more. Conservatives emphasize entrepreneurial dynamism less and the threat of government elites more. Electorates get a little uglier when faith in progress declines. Voters across the spectrum get more cynical and distrustful. They are quicker to perceive threats from The Other.

For example, anti-Semitism is a good barometer of a worsening public mood. According to the Pew Research Center, acts of hostility toward Jews are now rampant in 39 percent of countries, up from 26 percent in 2007. The U.K. Community Security Trust registered 1,168 anti-Semitic incidents in Britain in 2014, more than double the number from the previous year.