Run-of-the-mill violence Gene Lyons Probably every decent American had the same emotional reaction as former Supreme Court Justice Sandra Day O’Connor to the appalling events in her home state of Arizona. “It sounds like something that might happen in some place like Afghanistan,” she told The New York Times. “It shouldn’t happen in Tucson.” We keep saying that, but political assassinations and assassination attempts are more common in the United States than just about anywhere. During my adult life, lunatics with guns or bombs have changed American history more than any election: President John F. Kennedy, Sen. Robert Kennedy, Rev....