“In groups the most contradictory ideas can exist side by side and tolerate each other, without any conflict arising from the logical contradiction between them”, wrote Freud in his 1921 book Group Psychology and the Analysis of the Ego. One hundred years later, in an age of war, social networks, and ubiquitous threats to democracy, the questions raised by Freud are as relevant as ever. In today’s mass and group formations, psychological processes and mechanisms can be recognized as the...