A consequence of extreme political polarization is that people are punished for acknowledging a good idea if it comes from the other side. When people sort themselves into political tribes, finding something to admire in the opposing tribe doesn’t get interpreted as open-mindedness—it gets interpreted as treason.

This threatens to strangle our society’s capacity for self-improvement, because it perverts the process by which good ideas are distinguished from bad ones. People in a polarized society assess an idea by asking who proposed it, instead of what comprises it. If it came from an “enemy” group, the idea is bad. Humans exercise this sort of bias all the time, but a highly polarized society encourages it by turning it into a virtue.

Conservatives should take the left seriously—not just because it will improve the marketplace of ideas, but because their base is practically screaming at them to do it. The most recent generation of Republican congressmen, including outgoing Speaker of the House Paul Ryan, advocated Reagan-style economic policies that their voters don’t want.