At the University of Miami on Wednesday, Joe Biden had an odd fantasy. He declared that had he heard Donald Trump boasting about sexually assaulting women in high school, he would have taken “him behind the gym and beat the hell out of him.” Biden has said something similar before. He shouldn’t say it again.

The reason is obvious: America’s leaders shouldn’t glorify violence. It’s a point liberals have made many times since Trump’s political rise. They made it after Trump gestured to a protester at a Las Vegas rally in February 2016 and announced that, “I’d like to punch him in the face.” They made it in July 2017 when Trump tweeted an image of him body slamming and punching a man whose head was replaced by the CNN logo. They made it later that month after Trump encouraged police in Long Island to slam suspects’ heads against their police cars while taking them into custody. Again and again, liberals warned that Trump’s fantasies of violence could incite actual violence. And they have been proven right. A study published this month by researchers at the University of Pennsylvania found that when Trump held a campaign rally in a city, assaults went up.