On Wednesday, President Donald Trump retweeted anti-Muslim propaganda videos from a known hate group. The videos — one of which has been revealed to be fake — purport to demonstrate the dangers Muslims pose to Western society: that Muslim migrants beat up white Europeans, threaten Western culture, and mock Western religious figures.

As my colleagues at Vox have pointed out, Trump’s retweets fit with a pattern: He feels that the whole of Islam, collectively, is a threat to the United States and the West. He treats Muslims as a monolith, a group of millions who deserve to be banned from the United States. There’s a psychological theory that helps explain this tendency: “collective blame,” when we punish the whole for the actions of a few.

In some ways, Trump is channeling how many people in America feel about Muslims. We see collective blame rear its head after an act of terror committed by a member of the Islamic faith. “Maybe most [Muslims are] peaceful, but until they recognize and destroy their growing jihadist cancer they must be held responsible,” Rupert Murdoch tweeted after the 2015 terrorist attack in France. A similar sentiment often repeats on Murdoch’s Fox News.

There’s nothing logical about condemning millions of people — who are spread across the globe and are unrelated to each other except by religious tradition — for the actions of a few. You wouldn’t blame all white people for the actions of Dylann Roof, who walked into a church in Charleston, South Carolina, and killed nine African-American worshippers. You wouldn’t blame all Christians for the meanness of the Westboro Baptist Church.

Yet collective blame happens, with ugly consequences.