On May 14, 2022, an eighteen-year-old man murdered ten people and injured three more in a supermarket in a carefully chosen majority-black neighborhood in Buffalo, New York. His stated goal was to kill as many black people as possible.

The young man has been described in numerous media reports as “disturbed,” “quiet,” “idiosyncratic,” and “a lone wolf.” These portrayals undercut the reality of the murderer’s state of mind. He was and is not insane: His 180-page manifesto reveals no sign of the random, confused, and disordered thinking one might expect from a genuinely psychotic person. Nor is he a “lone wolf.” He is part of a massive, growing movement of adherents to an anti-Semitic conspiracy theory variously called “White Replacement Theory,” “Great Replacement Theory,” and “White Genocide Theory.”

It’s easy to confuse the actions of a die-hard, anti-Semitic conspiracy theorist with those of a person suffering from psychosis. Both kinds of people are disconnected from reality. However, a psychotic person’s problem is a malfunctioning nervous system. He or she sees and hears things that aren’t real, and these hallucinations can feed various delusions—think of Russell Crowe’s portrayal of mathematician John Nash in A Beautiful Mind.

Advocates of the Great Replacement Theory don’t hear voices or see phantoms. They are disconnected from reality for a completely different reason: They have allowed themselves to be convinced that all the world’s problems are caused by a secret cabal of Jews who are determined to eradicate white people by promoting, among other things, immigration and interracial marriage.