So maybe we can't draw any straight lines between the violent rhetoric coming from the far right and any particular violent act, but things like this really make me wonder.
Is there really any left equivalent of this? Sure, there were very insulting things said about Bush and Cheney, comparing them to Hitler and Mussolini (and to Dr. Strangelove and Sauron which should give us pause about how literally these comparisons were meant to be taken), but hunting licenses and targets? The Obama-Hitler comparisons (like the one illustrated above) strike me as in deadly earnest and meant to be taken quite literally. The left questioned Bush's legitimacy (as did a lot of people after the 2000 Election), but calling him an alien who should be overthrown by violence if necessary?
Right wing radio jocks call for the violent overthrow of the government routinely. Glenn Beck says the same thing ever so implicitly without ever saying so openly.
The last left wing extremist group to call for the violent overthrow of the government (and to act on it very violently) were these people, The Symbionese Liberation Army:
The SLA last dominated the headlines almost 40 years ago. The surviving members are now entering their dotage. There really hasn't been anything quite like them on the left since, not even the so-called "eco-terrorists."
The SLA got outclassed and out-slaughtered by a whole lot of people on the extreme right over the last 4 decades. We all remember Timothy McVeigh. Some of us remember the inhabitants of Elohim City and the many Missouri, Arkansas, and Oklahoma state troopers killed by those folks in the 1980s.
In the demands for civil discourse in politics following a horrendous act of violence that may or may not be politically motivated, I'm not buying the moral equivalency between left and right arguments.