“The American political system—which includes everyone from voters to journalists to the president—is full of rational actors making rational decisions given the incentives they face,” writes political analyst Ezra Klein. “We are a collection of functional parts whose efforts combine into a dysfunctional whole.”

In Why We’re Polarized, Klein reveals the structural and psychological forces behind America’s descent into division and dysfunction. Neither a polemic nor a lament, this book offers a clear framework for understanding everything from Trump’s rise to the Democratic Party’s leftward shift to the politicization of everyday culture.

America is polarized, first and foremost, by identity. Everyone engaged in American politics is engaged, at some level, in identity politics. Over the past fifty years in America, our partisan identities have merged with our racial, religious, geographic, ideological, and cultural identities. These merged identities have attained a weight that is breaking much in our politics and tearing at the bonds that hold this country together.

Klein shows how and why American politics polarized around identity in the twentieth century, and what that polarization did to the way we see the world and one another. And he traces the feedback loops between polarized political identities and polarized political institutions that are driving our system toward crisis.

This is a revelatory book that will change how you look at politics, and perhaps at yourself.