The great risk from political correctness on the nation's campuses is not that those who take offense will either win or lose the debate with those who set forth "offensive" facts or positions. The great risk is that the debate will never take place.

At Harvard last month, university President Lawrence H. Summers drew fire from the easily offended when he dared ask why fewer women than men seem to reach the highest ranks in mathematics and science. Summers asked whether fewer women might be willing to put in as many years of 80-hour weeks because of child-rearing, as well as whether women's minds might be genetically different.

The howls of outrage were predictable. Yet how are we to discover what factors may be blocking more women from success in these fields if we are not free to discuss and analyze any possible explanations, no matter how unlikely or unpleasant they may at first seem?

But we needn't go as far as Massachusetts to find an attempt to bully into silence someone who dares discuss matters that bother the easily offended.

At the University of Nevada, Las Vegas, 20-year professor Hans Hoppe, a world-renowned economist of the Austrian school, in March gave a stock lecture on planning for the future that he says has never resulted in complaints.

The lecture discussed different groups of people having different investment time horizons. The very young and the very old rarely concern themselves with the long-term economic future, Mr. Hoppe told his class, unlike married couples with children. Homosexuals, because they are less likely to have children and tend to live riskier lifestyles, also are less likely to plan for the long term, he said.

A student complained to university authorities, saying he had taken offense. The university then launched a months-long series of secret proceedings in which Mr. Hoppe's interrogators refused to consider signed letters from other students in the class as to the true nature of the discussion, but instead gave every appearance of presuming the tenured professor guilty. University authorities attempted to reprimand the professor and fine him.

Finally, the ACLU has stepped in. Coincidentally, the ACLU wrote UNLV's standards for teaching controversial matters. And local ACLU Executive Director Gary Peck says those guidelines, "which the university has blatantly violated in this case, don't merely allow professors to address controversial issues, they require them to address controversial matters."

"Academic freedom means nothing if it doesn't protect the right of professors to present scholarly ideas that are relevant to their curricula, even if they are controversial and rub people the wrong way," Mr. Peck says.

Indeed. The university should apologize to Mr. Hoppe and advise its students that the purpose of a university is to expose them to a wide range of new ideas --- even if some seem initially shocking or offensive.