A Duke University history professor recently suggested that many of the conservative and libertarian subjects of her book “seem to be on the autism spectrum.”

Nancy MacLean, author of the controversial book Democracy in Chains: The Deep History of the Radical Right's Stealth Plan for America, made the comments during a February 7 lecture at the New York City Unitarian Church of All Souls, where she was slated to discuss “the roots and agenda of the radical right.”

She was delivering a presentation on her book’s conspiratorial thesis about the American libertarian movement, which she claims originated with Nobel Prize-winning economist James Buchanan. Almost exactly one hour into the event, an audience member asked her “where his motivations” and ideas came from, and whether those are ideas are “ones of personal greed or…malevolence.”

After praising the interrogator for asking “such a profound question,” MacLean speculated that libertarian views might be the result of autism.

“As an author, I have struggled with this, and I could explain it in different ways. I didn’t put this in the book, but I will say it here,” she answered. “It’s striking to me how many of the architects of this cause seem to be on the autism spectrum—you know, people who don’t feel solidarity or empathy with others, and who have difficult human relationships sometimes.”

“I don’t know, that is speculation,” she reminded the audience, but despite the disclaimer, an audience member later referred to “autistic libertarians” in a question. At another point in the lecture, MacLean also called Trump’s federal judicial appointees “illegitimate.”

MacLean is a history professor and “scholar of the twentieth-century U.S.” at Duke, a private North Carolina university.