If there's one word any college student knows, it's "diversity." Every university, it seems, is "committed" to diversity -- or at least says it is. For example, Arizona State says on its Web site that it "champions diversity." But the reality is sometimes a bit different.

At the start of the year, ASU offered two English classes, ENG 101 and 102, taught by Professor G. Lynn Nelson. His Web page claimed, "My classes seek to help people discover within themselves the intertwined power of literacy and peace." Apparently they do that through segregation. You see those classes were, "For Native Americans only," as the site put it.

The university says it's fixed the problem, and that the classes are, in fact, open to everyone. "ASU promotes equal opportunity in educational programs and promotes respect for diversity," Executive Vice President Milton D. Glick wrote in a letter to the Foundation for Individual Rights in Education.

Sadly, even if this particular example has been fixed, it's symptomatic of a larger problem. When it comes to political philosophy, the modern American academy presents a grim front of uniformity -- an almost religious orthodoxy. That ought to trouble thoughtful people on both the right and the left.

Professor Stanley Rothman of Smith College examined the politics of more than 1,600 college faculty at almost 200 schools. He found that in "all faculty departments, including business and engineering, academics were over five times as likely to be liberals as conservatives." In fact, he determined that a leftist political viewpoint was almost as important a factor in hiring decisions as tangible academic achievements, such as publications and awards.

In The Chronicle of Higher Education, Professor Mark Bauerlein of Emory University points to three factors that explain why the academic world tends to exclude conservatives:

1. The Common Assumption. "The assumption is that all the strangers in the room at professional gatherings are liberals," he writes. "There is no joy in breaking up fellowship feeling, and the awkward pause that accompanies the moment when someone comes out of the conservative closet marks a quarantine that only the institutionally secure are willing to endure."

2. The False Consensus Effect. "That effect occurs when people think that the collective opinion of their own group matches that of the larger population." Bauerlein gives as an example the infamous statement ascribed to a New York Times film critic: "I don't know how Richard Nixon could have won. I don't know anybody who voted for him." The same thing was certainly said in many academic halls after the 2004 election.

3. The Law of Group Polarization. "When like-minded people deliberate as an organized group, the general opinion shifts toward extreme versions of their common beliefs," Bauerlein writes. In old left circles, this meant racing to embrace Stalin. Nowadays, the far left does not simply oppose the war in Iraq. Instead it argues, "BUSH LIED!" or asserts that neoconservative Israeli loyalists have hijacked our government.

Since they operate in an environment where their prejudices are supported and dissent has been thoroughly demonized, most teachers and administrators really do not understand what conservatives are so upset about.

There will, however, be consequences. As the radical polarization of the academy continues, more people will turn away from academic life, which will only make the problem worse.

What type of diversity does our higher educational system really need?

Our free, self-governing society requires the open exchange of ideas, which in turn requires a certain level of civility rooted in mutual respect for each other's opinions and viewpoints.

Liberals need to accept that conservatives deserve a place at the table and that we have productive ideas to discuss. That would be a critical step toward starting a real dialogue. But it won't happen until America's higher education community reaches out to include conservatives, instead of locking us out like so many non-Native American ASU students.

Ed Feulner is president of The Heritage Foundation (heritage.org), a Washington-based public policy research institute.