There has been a lamentable tendency in American public policy discourse since the 1960s to shift responsibility for acts committed by individuals to complex factors over which they supposedly have no control. Thus, within hours of President Kennedy’s assassination, some commentators claimed that it resulted from an “atmosphere of hate” in Dallas, not the actions of the man firing from the sixth-floor window of the Texas Schoolbook Depository, Lee Harvey Oswald. Similarly, in 1968, the Kerner Commission appointed by President Johnson famously pointed to “white racism” as the cause of riots in predominantly black areas of Watts and Detroit, instead of the street thugs, looters and radicals like the Black Panthers who shattered storefront windows, tossed Molotov cocktails into occupied buildings, and killed policemen and firefighters responding to the violence.

Variations on this theme have been regularly peddled ever since, including soon after the tragic wounding of Rep. Gabrielle Giffords, D-Ariz., and killing federal Judge John Roll and four others. Influential liberal activist and blogger Markos Moulitsas, for example, tweeted “Mission accomplished, Sarah Palin.” The New York Times’ Carl Hulse wrote that “while the exact motivations of the suspect in the shootings remained unclear, an Internet site tied to the man, Jared Lee Loughner, contained anti-government ramblings. And regardless of what led to the episode, it quickly focused attention on the degree to which inflammatory language, threats and implicit instigations to violence have become a steady undercurrent in the nation’s political culture.”