Offers a solid overview and summary on the academic literature on polarization in U.S. national politics. His original ideas aren’t as strong as the research he surveys, but Klein is keenly aware of his limits and fesses up almost every time he gets in over his head (I hate concluding chapters, he writes in his concluding chapter, but he does the concluding chapter stuff anyway). Very insightful book, by turns depressing and inspiring. I like the way Klein’s career has developed and his voice has matured.