The key moment in many revolutions comes when police and militaries refuse to fire on crowds. But what is difficult to explain about those moments is their infrequency. Soldiers and police come from the same society as the crowds. Why do they kill them? Why are elites and authorities able to rest so comfortably in the knowledge that in the final analysis, thousands of armed men will do what they are told? I think this is one of the most important questions we can ask, and not enough of us ask it.