Hate breeds hate. Killing brings killing. It starts slowly, and builds until both sides of have suffered enough to want it to end. As a matter of history, we have a rich tradition political violence. One which the left is a breath away from rediscovering.
The right conceives of the left through its own stereotypes. The O'Reilly's of the world do not conceive of the day when they might find themselves targeted in their turn. But violence is not so neatly constrained as to lie with one group and not another. If we are not to return to an earlier time, when domestic terrorism was commonplace and songs such as "Sister Jenny's Turn To Throw The Bomb" and "Blackleg Miner" were considered black humor grounded in truth, it is time to start seriously considering pulling back the rhetoric.