A 2010 survey by the American Association of Colleges and Universities found that of 24,000 college students, only 35.6% strongly agreed that "it is safe to hold unpopular views on campus." When the question was asked of 9,000 campus professionals—who are more familiar with the enforcement end of the censorship rules—only 18.8% strongly agreed.

Mr. Lukianoff thinks all of this should alarm students, parents and alumni enough to demand change: "If just a handful more students came in knowing what administrators are doing at orientation programs, with harassment codes, or free-speech zones—if students knew this was wrong—we could really change things."

The trouble is that students are usually intimidated into submission. "The startling majority of students don't bother. They're too concerned about their careers, too concerned about their grades, to bother fighting back," he says. Parents and alumni dismiss free-speech restrictions as something that only happens to conservatives, or that will never affect their own children.

"I make the point that this is happening, and even if it's happening to people you don't like, it's a fundamental violation of what the university means," says Mr. Lukianoff. "Free speech is about protecting minority rights. Free speech is about admitting you don't know everything. Free speech is about protecting oddballs. It means protecting dissenters."