Why We're Polarized

by Ezra Klein

Interlude What I’ve tried to do in the first half of this book is build a model of what’s driven American politics into its current place of bitter polarization. Let’s take a moment to put it all together. The human mind is exquisitely tuned to group affiliation and group difference. It takes almost nothing for us to form a group identity, and once that happens, we naturally assume ourselves in competition with other groups. The deeper our commitment to our group becomes, the more determined we become to make sure our group wins. Making matters worse, winning is positional, not material; we often prefer outcomes that are worse for everyone so long as they maximize our group’s advantage over other groups. The parties used to be scrambled, both ideologically and demographically, in ways that curbed their power as identities and lowered the partisan stakes of politics. But these ideologically mixed parties were an unstable equilibrium reflecting America’s peculiar, and often abhorrent, racial politics. The success of the civil rights movement, and its alliance with the national Democratic Party, broke that equilibrium, destroyed the Dixiecrat wing of the Democratic Party, and triggered an era of party sorting. That sorting has been ideological. Democrat now means liberal and Republican now means conservative in a way that wasn’t true in, say, 1955. The rise in partisanship is, in part, a rational response to the rise in party difference—if the two sides hated and feared each ...