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.