In 2015, an angry confrontation at Yale over how to dress up on Halloween caused a national sensation. Protesting students called for the university to fire Nicholas Christakis, a sociologist and physician, because they felt he and his wife, also teaching at Yale at the time, did not protect them from possible psychic injury.

The conflict started a week earlier, when the school's Intercultural Affairs Council sent an email encouraging members of the community to be careful not to offend their fellow students with culturally and racially insensitive costumes. Christakis' wife, Erika—an expert in early childhood education—responded with her own thoughts. "Is there no room anymore for a child or young person to be a little bit obnoxious…a little bit inappropriate or provocative or, yes, offensive," she wrote. From her perspective, American universities had "become places of censure and prohibition."

Students said that by sending her email, Erica Christakis had failed to create a safe space at Yale's Sillman College, where she served as associate master. Nicholas Christakis jumped into the fray, defending his wife's email, and he tried to engage in a dialogue with protestors in a courtyard. Scenes of students shouting at Nicholas and calling for his firing went viral.

Christakis not only held on to his tenured professorship, but three years later he was awarded the Sterling Professorship, Yale's highest faculty honor. And his confrontation with students kicked off an ongoing national debate about freedom of speech, political correctness, and sensitivity on college campuses.

As a sociologist, the 56-year-old Christakis is no stranger to highly charged group interactions. His new book is Blueprint: The Evolutionary Origins of a Good Society, which argues that our genetic makeup predisposes us to favor peaceful interaction and respectful co-existence over angry and violent mob rules.

Nick Gillespie sat down with Christakis to talk about his theory that what unites as humans is stronger than what divides us, the power of evolution as an explanatory system for society, and whether Enlightenment values such as civil discourse and intellectual freedom are still respected in our nation's colleges and universities.

Edited by Ian Keyser. Intro by Todd Krainin. Cameras by Jim Epstein and Kevin Alexander.

Music credit: 'Voyeur' by Jingle Punks

Photos by Ragesoss and Sibjeet, under a creative commons license.