Jonathan Haidt says he wants to bring fun back to college.

The New York University Stern School of Business professor and author of bestselling book “The Anxious Generation” has been teaching college students since the mid-1990s.

He’s noticed a change in the atmosphere on campus over the years, he said at an early-March fireside chat at NYU to introduce the school’s latest initiative, NYU IRL, which aims to help students be more present by offering phone-free spaces, among other efforts.

Haidt said life on campus has grown much more tense over the years. Colleges once felt like places where students could freely explore new ideas, he said, but in the era of smartphones and social media, many worry that something they say could spread online and get them ostracized or “canceled.” Instead of openly debating and learning from experts or one another, students often remain on the defensive.

This change came in tandem with the introduction of social media and the smartphone, he said, as well as the spike in youth mental health issues he has long warned about.