"Just because the dots between violent rhetoric and violent actions don't connect in this case doesn't mean you can afford to ignore the possibility -- or, as many fear, the inevitability -- that someone else will soon draw the line between them.... Now that the right has proved to the world that it was wronged, this would be a good time to prevent the next tragedy from destroying its political momentum. Despite what we eventually learned about the shooter in Tucson, should the right have really been so shocked that many feared a political connection between the heated rhetoric of 2010 and the shooting of Giffords?" - Joe Scarborough.
My only caveat is that we don't yet really know the full background to Loughner's mental illness.
So far, the paranoia and conspiracy theories dominate - but they also dominate the atmosphere of the far right. And when a mentally ill young man complains of the "Broken United States Constitution", or regards legal tender as illegitimate “I did not pay with gold and silver!”, some of this nuttiness has penetrated. It didn't come from nowhere. And the critical point from the very beginning was not that Loughner was some kind of trained militia member killing a foe, but a mentally unstable person who, because he is mentally unstable, might be susceptible to extreme rhetoric from authority figures.