What happened Monday night at the Correspondents’ Dinner wasn’t surprising, at least for people who study violence.

Political violence in the United States has been rising for years. And the conditions that drive it - extreme polarization, a President who stokes it, easy access to guns, and a social media environment that radicalizes - are all in place.

That means incidents like this are going to happen again unless we change things. Which so far we haven’t.

I talked about this on CNN last night: