Last I heard, there's nothing solid tying Loughner to the more violent right-wing rhetoric. It may have affected him, but if so, it doesn't show up strongly in his writing.
The one relatively good thing in the situation is that he's still alive, so we've got a better chance of learning about his influences.
There's a wide insurrectionist streak in the American right, but what's unusual is that Loughner didn't stop with killing a politician or a politician and a judge. He went after a crowd of people who weren't in the government, and I can't think of any other American examples of assassination combined with mass murder.
This is terrorism, and I think he was influenced merely because terrorists have moved the Overton Window-- the range of what's thinkable.  Killing random people is how you say you're serious.
If this is true, there's no obvious solution. I'm hoping that terrorism will fade out eventually, and expecting that no one will be quite sure why.
 I think I'm right about this-- if not, I'm sure you'll tell me.
 OK, it's a slight extension of the idea of the Overton Window.
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