How do societies work their way out of polarization? And what does the answer have to do with broken trucks, the Apollo program, the movie 'Watchmen', Iroquois Native Americans, a new idea for social media algorithms, moral taste buds, and how we can take advantage of the common threads that bond us -- coming to see each other again as fellow travelers improvising their way through the same noisy world?

What do propaganda posters have in common across nation and time, and how is that related to the medial prefrontal cortex? What is behind repeating cycles of societal polarization? What does any of this have to do with the American Civil War, hippies vs soldiers, border ruffians vs free-staters, hanging chads, Pearl Harbor, and why education can serve as an immune response to mind viruses?

Would a utopia be possible? Or does our innate tribalism and jealousy make perfect societies difficult to achieve? Do we secretly love hierarchies? Why are primate brains such excellent detectors of unfairness? Why do things become more desirable when we’re told we can’t have them? Did the church’s disavowal of first-cousin marriage lead to better politics? This week Eagleman talks with psychologist Paul Bloom about the (im)possibility of achieving societal utopias.