U.S. Rep. Jack Bergman (R-Mich.), center, leaves the scene of  the shooting at Eugene Simpson Stadium Park in Alexandria, Va., on Wednesday. Republican congressional members were practicing for a charity baseball game. (Alex Wong/Getty Images)

On Wednesday, a gunman opened fire on a congressional GOP baseball practice in Alexandria, Va., and died after a gun battle with police officers. The gunman’s social-media posts suggested anger at Republicans generally and Trump in particular, a possible motive for the shooting. Over the past several years, the Monkey Cage has published a number of posts related to similar violence, offering social science’s insights into such questions as political violence, gun regulation, terrorism and political polarization. Below we offer a few highlights and bulleted lists of relevant posts for further reading.

Terrorism and mass shootings. In December 2015, Nathan Kalmoe reported on his survey of Americans’ attitudes toward violence against the government, finding that “although most people opposed violence, a significant minority (ranging from 5 to 14 percent) agreed with each violent option, and 10 to 18 percent expressed indifference about violence in politics. This implies that millions of ordinary Americans endorse the general idea of violence in politics.” Those attitudes spanned the political spectrum; Democrats, Republicans, liberals and conservatives were equally likely to believe such violence might be justified. Erica Chenoweth wrote about research showing that mass shootings and terrorism are “contagious” and that more media coverage makes more attacks more likely. Erin M. Kearns, Allison Betus and Anthony Lemieux explained that, yes, some terror attacks are underreported — but that those carried out by Muslims tend to overshadow others.

Regulating guns and reducing violence. Mass shootings are often followed by public discussions about whether various gun policies might have prevented the violence. After the Charleston, S.C., church shooting, David Fortunato examined the claim that had parishioners been carrying guns themselves, they might have prevented their own deaths. Last spring, Alexandra Filindra explained the research, including her own, that has found that support for gun rights, and against gun regulation, is strongest among whites who are racially prejudiced. Mark Joslyn and Don Haider-Markel explore the idea that, increasingly, a gun culture has developed in which “gun ownership represents a cluster of values, such as strong individualism, distrust in government and personal freedoms” that are linked to the Republican Party.

Meanwhile, because the gunman was expressing strong political views, questions arise about whether the extreme polarization in U.S. politics is hurting our democracy. Several Monkey Cage authors have taken a look.