Have American academics lost their collective minds?

This week, Columbia University allowed Iran's loony President Mahmoud Ahmadinejad to be a lecturer on its campus.

In the circus that followed, Ahmadinejad weighed in on everything from Israel to homosexuals, and came off, as expected, like a petty bigot. All the same, by his very presence on an Ivy League stage, Ahmadinejad showed the world that a top American university considers his odious views worth showcasing.

Ahmadinejad has denied the first Holocaust and all but promised a second one. His country's government is on its way to having a nuclear bomb, sends Iranian terrorists into Iraq to kill American soldiers and customarily jails journalists and expels politically active students from their universities.

But all that apparently still earned Ahmadinejad his publicity coup — and occasional applause from the Columbia audience.

Yet in this time of war, Columbia won't allow our own Reserve Officers' Training Corps (ROTC) on its campus.

One wonders whether Columbia would have invited Hitler as well. Don't laugh — a foolish dean did indeed announce two days before Ahmadinejad's visit that he would have likewise invited the Nazi fuhrer to speak.

Along with a general lack of common sense — and decency — the powers that be at Columbia, for all their erudition, don't seem to understand the line between responsible debate and crass propaganda. But sadly they're not alone in failing to understand how free speech works in a free society, especially on university campuses.

Take what happened this month at the University of California, Davis. Under pressure from campus feminists, the university withdrew an invitation to former Harvard University President Larry Summers to speak at a board of regents dinner.

Now, Summers has never threatened to blow up another country, but apparently he has committed a far greater sin for academics. The distinguished former secretary of the Treasury in the Clinton administration ran afoul of Harvard feminists for his off-the-cuff theorizing a few years ago about why women were not better represented on math and science faculties.

As penance, Summers allotted some $50 million in various earmarks for feminist programs at Harvard. But professors at UC Davis argued successfully that Summers was still unsuitable to speak at the regents event.

Meanwhile, the University of California, Irvine, this summer first offered, then rescinded, and, finally amid furor, re-offered their law school deanship to Erwin Chemerinsky. The liberal and outspoken Chermerinksy's academic qualifications — he's been a distinguished law professor at Duke — were never in doubt. But apparently the university's chancellor, Michael Drake, was first fearful of offending a few donors by the appointment — and then more fearful of the public outrage should he not hire Chemerinsky.

At Stanford University's Hoover Institution on War, Revolution and Peace, where I work, the decision to invite former Defense Secretary Donald Rumsfeld to serve on one of its task forces on ideology and terror as a distinguished visiting fellow caused furor on campus.

Rumsfeld was the youngest secretary of Defense in our history (when he served in the position during the Ford administration), and the only one to hold the distinguished office twice. Before resigning amid public controversy over the Defense Department's inability to stabilize Iraq, Rumsfeld helped to plan brilliant victories over the Taliban and Saddam Hussein and sought to reform the American military.

Yet more than 2,000 Stanford students and professors signed a petition in an unsuccessful effort to block the Rumsfeld appointment, arguing that his record in Iraq forfeited his very right to serve on a Stanford-affiliated task force.

In each of the above cases, the general public has had to remind these universities that their campuses should welcome thinkers who have distinguished themselves in their fields, regardless of politics and ideology. The liberal Chemerinsky, the Clinton Democrat Summers and the conservative Rumsfeld have all courted controversy — and all alike met the criterion of eminent achievement.

But the propagandist Mahmoud Ahmadinejad has not. Unlike Chemerinsky, Rumsfeld and Summers, he used the prestige of an Ivy-League forum solely to popularize his violent views — and to sugarcoat the mayhem his terrorists inflict on Americans and his promises to wipe out Israel.

Here's a simple tip to the clueless tenured class about why a Larry Summers or Donald Rumsfeld should be welcome to speak, and Mahmoud Ahmadinejad shunned: former Cabinet secretaries — yes; homicidal dictators killing Americans — no.

Finally, universities should be free of sin before casting ideological stones at others. There are enough self-inflicted problems on their own campuses to keep them busy — from the declining skills of today's college students to skyrocketing tuition and exploitation of graduate students and part-time faculty. They needn't create more where they don't exist.

Victor Davis Hanson is a classicist and historian at the Hoover Institution at Stanford University. Reach him at author@victorhanson.com.