Before western societies became too squeamish to put down riots effectively, rioters were treated as wild beasts and shot down in the streets. Unless and until we return to doing that or engaging in some similar and equally effective method of putting an end to urban riots, our perpetually aggrieved and disgruntled mad dogs will use any pretext to continue and expand their uncivilized and destructive activities . . . to the point that a real race war will be the only alternative to the destruction of civilized life.
For a look at how and why the situation in Wisconsin's largest city has been spiraling out of control and what it portends, take a gander at this essay.
After doing so, one would do well to remember that civilization as we know it really is a very recent development. It is not mankind's historic norm. It instead is a thin and fragile veneer that suppresses the barbaric and chaotic conditions in which human beings led nasty, brutish, and short lives throughout a vast majority of the time that homo sapiens have existed on our planet.