Why We're Polarized synthesizes several years of Klein's political reporting into a clear thesis:

Increasingly overlap between our personal and political identities has combined with technological amplification of salient challenges to those identities to both reveal pre-existing political differences and manifest conflicts de novo.

This thesis is supported by a smattering of evidence from behavioral psychology, political science, and sociology. My principal critique of Klein's work here is that these social science results are taken at face value, with little skepticism, and immediately held up as keys to the cipher of American democracy.

As a life scientist, you're trained to treat new results in the literature as a starting point for a new therapy or application, rather than a product ready for market. Klein's treatment of the social science literature feels a bit like jumping from the first proof-of-concept in a mouse model, skipping clinical trials in humans, and implementing the new therapeutic idea as frontline therapy.

This is to say -- take the first half of the book with a grain of salt.

I found Klein's chapters on the role of the media (an area he is uniquely qualified to cover) and asymmetry between the American political parties to be particularly insightful. His media thesis boils down to: "The media's most important decision is what we cover, not how we cover it."

This analysis runs counter to the media's self-portrayal as an objective institution in a manner that feels honest and accurate. Despite Klein's hesitancy in his concluding policy prescriptions, I also found the concluding chapter to be well-measured and systematic in it's approach.

Taking the past decades of American political life into account, it's difficult to argue with Klein's central premise that the American system of government is not suited to deal with partisan division as the central axis of conflict. Structural reforms are necessary if this is to be the continued state of the world.

Klein is also to be commended for his nuanced view of polarization as a concept. As he writes, it is easy for authors to use "polarized" as a pejorative, ignoring the suppression of real conflict that occurs in the absence of clear political choices. In this light, Klein's prescriptions to amend our system to account for the reality of polarized political identities, rather than attempting a return to the conflict suppression of mid-twentieth century American, seems especially disciplined.

Pair with: Dancing in the Glory of Monsters: The Collapse of the Congo and the Great War of Africa for a consideration of how prolonged failure of governing institutions can encumber a society.