Violence polarizes. It makes people pay attention. It makes people take sides. And this goes for violence from authorities like the police as well as protesters.
Citizens of Ferguson clean up after the police and violent protesters.
It doesn’t take many people, committed or crazy, in masks or police uniforms and riot gear, to hijack a story or a movement by doing something provocative. Surely, almost no one who lives in Ferguson is happy to see young men throwing Molotov cocktails or looting stores.
Effective policing entails separating those seeking a confrontation with the police or a chance to act out from a larger community of protesters. It should be easier to make this separation in Ferguson, where everyone seems to say that some large share of the violent protesters are from elsewhere. But the policing in this very small city has been anything but effective (see Zack Beauchamp’s piece at Vox). When military assault vehicles appear in the streets, the citizens of Ferguson are likely to be just as angry at and scared of the police as the “agitators.”
Putting the police in the hands of the state highway patrol and Captain Ron Johnson was an effort to improve the policing and unite the nonviolent protesters with authorities. It may still work, but the local police have been able to undermine that alliance by sporadically releasing odd piece of information and videotape.
This won’t go on forever, but it’s not yet clear when the nightly unrest will end.
And the awful thing: would there be national attention to the racial politics of policing and 
the militarization of local police departments if the protests hadn’t gotten out of hand and continued?
When their efforts spur stories about the issues, protesters are winning. In America, violence usually undermines stories about policy. But that’s not what’s happened in Ferguson–yet. Indeed, overly aggressive and visibly ineffective efforts at social control have provided with a chance to turn the terrible case of a police shooting into a larger cause. It doesn’t usually happen, but this time–thus far–there’s national attention to larger social problems–and some sympathy for substantial reforms.
Here’s another sign: Prof. Lindsey Lupo, author of Flak-Catchers: One Hundred Years of Riot Commission Politics in America,
notes that that most coverage hasn’t called the violent disturbances at night, “riots,” a word that dismisses notions of larger causes.
One reason, I think, is that there has been some softening up of the body politic, which is more ready for action on policing and race in the wake of the visible campaigns around the shooting of Travyon Martin that led to…..nothing.
Politics Outdoors 
Dr. Meyer
What I am trying to wrap my mind around is how we define violence. It is striking to me that we seem more concerned about property crime (looting) than the use of force which results in death. How do we reconcile the praise of Bundy and his armed defenders and the treatment of protesters in Ferguson? Obviously some are allowed a degree of violent posturing that others are not. I have come to understand that violence, like race, is culturally and socially described. Now I’m trying to understand just what we mean by “violence”.
People often deploy a double standard on violence, supporting instances they judge necessary–when committed by people they like. Dropping bombs on ISIS, for example, is clearly violent, but at least so far, broadly supported.
Breaking store windows and throwing rocks–or Molotov cocktails–is also violent.
So, there’s definitions and there’s Cliven Bundy.
I’m willing to describe intentional damage to persons and property as violent. Threatening to shoot Bureau of Land management officials (as Cliven Bundy’s supporters have) is clearly threatening violence, and veers to terror. I’ve written about it here, e.g., https://politicsoutdoors.com/2014/04/24/cliven-bundy-gets-real/
Over time, much of Bundy’s mainstream conservative support defected, and the threat of violence was one reason. I think even those who remained would describe Bundy’s conduct as threatening justifiable violence–to counter the threatened violence of the government. No?