Trying to understand a riot is never easy, especially when it's still raging. The rolling unrest tearing through multiple American cities is many things. But it's not simple. The horrific slow death of a black man at the hands of an impassive white police officer was just the match that lit a building fury. The police statement — which described a suspect "under the influence" who suffered "medical distress", with no mention of the police officer pinning him down — didn't help. Neither did the four-day delay in bringing charges against the officer. And the President's tweet that "when the...