Fact is that antisocial behavior always happens on the margins, so how you or I would respond isn't relevant. What's relevant is how external sources affect people who are intellectually or emotionally challenged.
The Giffords shooting provides a good opportunity to apply the thesis of "Such-and-Such Is Fiction" to a real-world example. Therefore, I continued with these sarcastic comments:
Neither the Bible nor the Koran ever influenced anyone. Same with speeches by Lincoln, Churchill, FDR, JFK, MLK, Reagan, et al. Same with right-wing hate speech. People's beliefs and actions materialize out of thin air for no discernible reason and are totally unconnected to external sources.
The 9/11 terrorists weren't influenced by hate speech similar to, but worse than, the hate speech used by today's conservatives. No, they killed 3,000 Americans for reasons unrelated to what they were programmed to believe by relentless hate-filled lies and propaganda.
"America = den of Zionists" and "Obama = Kenyan/Muslim/socialist/terrorist." Two examples of false propaganda designed to stoke fear and hate.
Rightist vs. leftist hate speech
Can you imagine Reagan saying Democrats such as Tip O'Neil threatened the American way of life or were a danger to the country? I can't.
P.S. My list included FDR, JFK, and MLK, so clearly I think liberal speech can affect people as much as conservative speech.
Someone named Windy chimed in:
George W. Bush launched an illegal war based on false intelligence that has killed thousands of innocent people. When any Democratic politician does that, you have my permission to say nasty things about him or her. Until then, no.
For more on the subject, see Loughner Echoes Right-Wing Extremists and Debating Loughner's Influences.