Looking at data from the civil rights era, Wasow argues that “proximity to black-led nonviolent protests increased white Democratic vote-share whereas proximity to black-led violent protests caused substantively important declines” — enough to tip the 1968 election from Hubert Humphrey to Nixon. More broadly, in news coverage and public opinion from those years, nonviolent protests (especially in the face of segregationist violence) increased support for civil rights, while violent protests tipped public opinion away from the protesters, and toward a stronger desire for what Nixon called law and order, and Wasow calls “social control.”…

For liberals, meanwhile, or anyone committed to reform without revolution, recognizing how the politics of riots usually play out imposes a special burden to forestall and contain them — and when that isn’t possible, to clearly distinguish the higher cause from the chaos trailing in its wake.

My suspicion is that this will be more easily accomplished in 2020 than it was in 2016 or 1968. Across his presidency Trump has been more a Wallace than a Nixon, less “law and order“ than “the law for thee but not for me,” and his obvious disregard for civic peace makes it hard for him to campaign as its custodian. At the same time, the manifest injustice of George Floyd’s treatment by the Minneapolis police has imposed a limit on Trump’s demagoguery; even the president claimed to be honoring Floyd’s memory in the same breath that he attacked the rioters. And unlike four years ago, in 2020 Trump’s waning re-election hopes probably depend on winning a higher-than-usual number of black and Latino men, which mean that the politics of racial backlash are more fraught for his strategists than one might usually expect.