MICHAEL BARONE: A Democratic Cassandra gets canceled for telling the truth.

“I think Democrats are ignoring this problem, are hoping that it will go away. And it’s not going to go away.” That was CNN anchor Don Lemon, speaking to colleague Chris Cuomo on Tuesday night, on the Republican National Convention, five days after the Democrats had adjourned their convention sine die (as they used to say) during which they ignored “this problem” for four straight nights.

What was “this problem?” “Guess what, the rioting has to stop,” Lemon went on. “Chris, as you and I know, it’s showing up in the polls, it’s showing up in focus groups. It’s the only thing right now that’s sticking.”

“Sticking” in this context means hurting the Democratic ticket. Last week, when it evidently didn’t show up at the polls and in focus groups, Lemon was not giving similar advice to the party he obviously favors.

But he might have done so if he had listened to a shrewd Democratic political consultant — and if that consultant had not been “canceled” for giving similar advice three months ago.

The consultant in question is 28-year-old David Shor. On May 28, three days after the death of George Floyd, he made an interesting point in a tweet: “Post-MLK-assasination race riots reduced Democratic vote share in surrounding counties by 2%, which was enough to tip the 1968 election to Nixon. Non-violent protests *increase* Dem vote, mainly by encouraging warm elite discourse and media coverage.” In the tweet, he cited Princeton political scientist Omar Wasow’s 53-page paper entitled “Agenda Seeding: How 1960s Black Protests Moved Elites, Public Opinion and Voting.” By the way, if it matters, Wasow is of African descent and co-founder of the social networking website BlackPlanet, which was sold in 2008 for $38 million. The paper, perhaps revised in the editing process, appeared in the American Political Science Review.

It didn’t matter. Shor lost his job, the riots rolled on, and now — as should have been predictable to anyone who wasn’t an idiot — they have hurt the Democrats. Epistemic closure has its costs.