Glenn Greenwald leads a discussion about the moral and practical issue of violence in protests.

Here is what I think. It may be inevitable that people who are long-oppressed and then suddenly angered by violence break out in violence. But it is crucial for their movement to organize itself to reject that violence, so that repressive forces can't use that violence to smear the cause and repress the protests.

In case the black bloc shows up, protesters should train in advance to insist it is not welcome and not part of their protest. Besides, surely some of the black bloc are provocateurs, perhaps thugs without uniform, and their aim is to harm the cause.