“The idea that violence is legitimate for political purposes has moved into the mainstream,” said Robert Pape, a political science professor at the University of Chicago. “It’s still a minority. … But if you’ve got 10 percent or 15 percent of a community that believes that violence is acceptable for some political causes, that just encourages more violence for those causes.”…

According to Pape, the rising threat of violence that he and his colleagues at the Chicago Project on Security and Threats study is not exclusive to the political left or right, with Pape citing as examples the attempt on Kavanaugh’s life and the white supremacist mass shooting in May at a grocery store in Buffalo, N.Y.

Rather, the issue comprises multiple factors, which Pape analogized to a three-legged stool: These include an individual’s volatility and opportunity to inflict harm, as well as the degree of community support for politically inspired acts of violence.

Although it’s difficult to pinpoint when sympathy for political violence began “seeping into the mainstream,” he said, “we can be confident that these community sentiments for violence are here today.”