The visit of Pope Benedict XVI to Turkey today will be a test of an idea which he elaborated in the Regensburg address that caused so much stir back in September: the idea that reason is essential to dialogue. To write that address, the pope drew on his experience as a university teacher in Bonn back in the late 1950s. At Bonn, the pope later recalled of the university community, “we made up a whole, working in everything on the basis of a single rationality with its various aspects and sharing responsibility for the right use of reason.” A shared commitment to reasoned dialogue fostered comity between the two theological faculties and other departments, even when there was “radical skepticism” about “something that did not exist: God.”

What the pope was saying was complex. What masquerades as tolerance can be intolerance. And acts that might be portrayed as intolerant can benefit the cause of tolerance.

The Turkey question is deeply important to the entire world. We are longing for evidence that a Muslim country can remain tolerant. But what is also interesting to Americans is that we have our own variation on the “Turkey question” — the question of tolerance on our campuses. Columbia University, especially, deserves attention here, for recent events there indicate that the rational idea of a university has been turned on its head. The analogy seems odd, but as a recent graduate of Columbia, I’ve come to think it is worth pursuing.

Consider the history of that great university. In 1917, with America’s entry into the Great War, Columbia’s trustees ratified a resolution vesting President Nicholas Murray Butler with the authority to impose an oath of “unqualified loyalty to the Government of the United States. “Butler realized that in wartime especially, allegiance to government is vital: “What had been tolerated before became intolerable now. What had been wrongheadedness was now sedition. What had been folly was now treason.” While some would say Butler proscribed academic freedom, he acted not to enforce ideological correctness, but to draw a line between dissent and treason. The war changed everything. There must now be a distinction between those who were and who were not, in Butler’s phrase, “with whole heart and mind and strength committed to fight with us to make the world safe for democracy.”

Nowadays, Columbia is different. Such “radical skepticism” as the pope described is permitted, but only as long as it does not challenge the administration’s ideological commitments. With skepticism confined in this way, academic freedom has come to mean the freedom not to dissent.

This topsy-turvy order became clear to me during the October 4 student attack on representatives of the Minutemen, who oppose illegal immigration. The College Republicans, a group in which I had been active, had invited this group to speak on illegal immigration at America’s Southern border. Not everyone agrees with the Minutemen, including The New York Sun. Still it seemed wrong to all of us who watched the replay on the Internet that Jim Gilchrist, the speaker, could not deliver his speech. A crowd led by the student chapter of the International Socialist Organization rushed the stage. The university’s own police failed to stop the crowd.

Two days later, a university-wide communication from President Lee Bollinger decried the incident as a violation of free speech and even promised an investigation. However, the violation occurred because of the university’s passivity.

One protester reportedly remarked, “I don’t feel like we need to apologize or anything. It was fundamentally a part of free speech. … The Minutemen are not a legitimate part of the debate on immigration.” The net result was that free speech was enjoyed exclusively by members of the International Socialist Organization and the Chicano Caucus and their sympathizers.

All this should come as no surprise, for Mr. Bollinger has a different view of freedom than his predecessor. A year ago, Mr. Bollinger said of Butler that his measure was “the best-known invasion of academic freedom during the World War I era.” After mentioning cases in which professors were fired or investigated, Mr. Bollinger went on to say without qualification: “The McCarthy era also posed significant challenges to academic freedom.” Mr. Bollinger was willing to discount the necessity of allegiance that Butler acknowledged.

But as we know now, McCarthyism may need to be revisited. The tactics of the McCarthyites were deplorable, but the reality was that some of the people investigated were indeed secret communists who were not always acting in the interest of the liberal culture of America.

If Butler seems so distant to us today, it is also perhaps because he could speak so unequivocally about “folly” and “wrongheadedness.” My own view is that his words in fact indicate an appreciation of reasonableness that today’s free speech advocates lack. Dialogue at Columbia is becoming futile, and I and other Columbians were disappointed.

When and how did the academic flight from reason occur? We find a clue in the historical context of the pope’s Bonn experience, which was a luminous interlude in dark times, not only because of the Nazi tyranny that preceded it, but also because of the student revolution that would later shake the world in the 1960s, and from which German and indeed all Western universities have yet to recover. In their rebellion against the authority of reason, these two very different periods share a common trait.

Reason is not only the essential requirement for dialogue within the university, but also in the world at large. This is why the pope concluded his address by saying of reason that “to rediscover it constantly is the great task of the university.”

The Columbia fiasco reminds us that dialogue is the privilege of reasonable minds. When the pope journeys to Turkey, let’s hope that his commitment to reason will be reciprocated. But we also need such reciprocity at home, at Columbia, and at other universities.

Mr. Plieninger earned a master’s degree from the department of Germanic languages and literature at Columbia University in 2005.