Liberal protesters didn't stop Donald Trump in Chicago. They helped him.

What did the protests actually accomplish? Yes, the Trump rally was called off. But the candidate himself ended up getting hours of free air time out of it, as he called in to MSNBC, Fox News, and CNN to discuss the night’s events over unsettling footage of mob violence. He also got to portray himself as a martyr for free speech and his supporters as the victims of intolerance and aggression at the hands of left-wing activists. And in the days since Friday, Trump has gone even further — to blame the violence at his rallies on “our communist friend” Bernie Sanders and threaten ominously that he might begin sending his supporters to disrupt Sanders events as retaliation.

Why would Trump embrace and encourage political violence instead of condemn it? Because he intuitively understands something that left-wing protesters apparently do not: When anarchy spreads, it’s the toughest, most authoritarian candidate who benefits, since he gets to sell himself as the only one capable of restoring law and order. So if you want to stop Trump, don’t contribute to stirring up trouble at his rallies.

Understanding this isn’t complicated. All it takes is rudimentary analysis of the political situation. Why, then, are growing numbers of progressives going to Trump campaign events looking for trouble, and sometimes acting in foolish ways that might plausibly result in someone ending up dead? And why are people cheering on such behavior on social media?