Quoted: Pamela Oliver, a University of Wisconsin sociologist who studies social movements, agrees that if Trump becomes the GOP’s nominee this fall, it will further galvanize minority voters and civil-rights activists. But she warns that the racially tinged conflicts at Trump rallies have a dark side that could backfire on protesters. When majorities whip up racial animus, she says, “it often ends very badly for minorities.” If the skirmishes, violence, and clashes with law enforcement continue, Trump’s campaign could also end badly for some legally vulnerable police officers.