Anne Applebaum: We all pay for Trump's Twitter trolling

Though it has a long way to go, the science that underlies the fight against extremism has made a lot of progress in recent years. Psychologists and social media analysts have found that people become radicalized by other members of a group. People seek out the like-minded, then enter online forums, then become more extreme by reading and communicating with others. As the study of history will also tell you, individuals will do things as part of a mob that they would not do alone.This is the psy