Tens of millions of Americans are watching this year's presidential debates. And while the myriad rules governing these events may be controversial, at least voters have a chance to hear from both of the men who want to lead this nation for the next four years.

           
But imagine if, instead of hearing from both candidates, voters were exposed only to one, over and over. That would be an indoctrination, not a debate. Americans wouldn't stand for such a thing. So why are we allowing it in higher education?

           
Universities are supposed to be about exploring ideas and searching for truth. Instead, many schools have become liberal bastions, where dissenting ideas are all too frequently scoffed at or even stamped out.

That makes sense when you consider who's doing the teaching. According to a poll by the Higher Education Institute at UCLA, 48 percent of college faculty members and administrators describe themselves as "liberal" or "far left." Another 34 percent claim to be in the middle, with only 18 percent calling themselves "conservative" or "far right."

Those numbers are quite different from what we see outside the ivied halls of academe. According to the Pew Research Center, only 20 percent of the general public call themselves liberal, while 33 percent say they're conservative.

           
Liberal bias on campus manifests itself in many ways, but what's probably the most dangerous is that students can spend years in school without hearing from a conservative. "[Students are] not really exposed to views outside of a radical-leftist perspective," self-declared conservative professor James Miller of Smith College said in The Chronicle of Higher Education. "They have no idea that there are other views out there." Conservative law professor Carol Swain of Vanderbilt told the Chronicle, "Most students will not get the kind of education their parents would hope they get and will not be exposed to different sides of an issue."

           
When students dare to speak out, they're often threatened. At Georgia Tech, a student made the mistake of telling her professor she planned to attend C-PAC, an annual gathering of conservative leaders. "Then you will probably fail my class," he told her. He was as good as his word. He failed her on the first test and frequently blasted conservatives in class. Eventually, she withdrew.

In another case, a student at Metropolitan State College in Denver testified before the Colorado legislature that his politics got him thrown out of a course. "I don't want your right-wing views in my classroom," the teacher told him.

When the student finished testifying, the professor accosted him, right there in the hearing room. "I got my Ph.D. at Harvard. I'll see your [expletive] in court. Then we'll see a chilling effect."

           
This incident actually spurred university administrators to action. Under pressure from activist David Horowitz and the Colorado state legislature (under the leadership of the dynamic Republican State Senate President John Andrews), the entire University of Colorado system adopted a provision promising, "Colorado's institutions of higher education are committed to valuing and respecting diversity, including respect for diverse political viewpoints." That wording echoes a key provision of Horowitz's "Academic Bill of Rights," a document that also aims to forbid the hiring (or firing) of professors on the basis of their political opinions.

I applaud the University of Colorado administration for taking this action. What a shame, though, that it was even necessary.

But since it is, federal lawmakers ought to consider something similar. Next year, Congress will renew the Higher Education Act, which regulates federal funding and financial aid to college students. Instead of simply shoveling out more money, this time lawmakers also should update the act to ensure it protects all ideas -- including conservative ones -- in universities.

That doesn't mean the government ought to be assigning texts or grading tests. But it does mean that teachers and students deserve to know they can espouse conservative ideas in the academy without fear of being fired or failed.

After all, don't we deserve at least as robust a debate on campus as we already have in the political arena?

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