The Vox editor explains why there’s no chapter devoted to Facebook or Twitter in his new book about how the US is more divided than ever. Ezra Klein, the editor-at-large at Vox and the host of The Ezra Klein Show podcast, has a new book out called Why We’re Polarized. He agreed to chat with us about the book’s arguments and the role that technology plays in it. Nicholas Thompson: Welcome, Ezra! The book is marvelous. I read the galleys pretty much cover to cover and was captivated. You take readers through American history and explain persuasively that we’re vastly more polarized now than in the past. And your publisher craftily timed your release exactly to the impeachment hearings, which were perhaps the most partisan moment in history. NT: When I started, I expected to find a chapter on filter bubbles and Facebook. Or about how Twitter pushes political conversations to extremes. Or how YouTube takes people from cookie-baking tips to jihadism. There are a few bits about tech, many of which are intriguing. But why don’t we start with this: Explain your general thesis and why the social platforms play a relatively small role in it. EK: In a way, these answers are the same...