This is a podcast episode literally years in the making. It’s an excerpt — the first anywhere — from my book Why We’re Polarized. A core argument of the book is that identity is the central driver of political polarization. But to see how it works, we need a better theory of how identities form, what happens when they activate, and where they fit into our conflicts. We’ve been taught to only see identity politics in others. We need to see it in ourselves. If you’re a longtime listener, this excerpt — like the broader book — will tie a lot of threads on this show together. If you’re a new listener, it’ll give you, I hope, a clearer way to understand a powerful driver of our politics and our lives.  Why We’re Polarized comes out on January 28. You can order it, both in text and audiobook forms, at WhyWerePolarized.com. Find the audio book on Audible.com New to the show? Want to listen to Ezra's favorite episodes? Check out The Ezra Klein Show beginner's guide. Want to contact the show? Reach out at ezrakleinshow@vox.com You can subscribe to Ezra's podcast Impeachment, explained on Apple Podcasts, Spotify, Stitcher, Overcast, Pocket Casts, or your favorite podcast app. Credits: Producer and Editor - Jeff Geld Researcher - Roge Karma Learn more about your ad choices. Visit podcastchoices.com/adchoices