In a wide-ranging address at Harvard, former Mayor Bloomberg ranged from defending the right to build a mosque near Ground Zero to attacking efforts to ban federal public-health research on guns. But the core of his remarks, excerpted below, took on liberal intolerance on campus today. — THE EDITORS

Repressing free expression is a natural human weakness, and it is up to us to fight it at every turn. Intolerance of ideas — whether liberal or conservative — is antithetical to individual rights and free societies, and it is no less antithetical to great universities and first-rate scholarship.

There is an idea floating around college campuses — including here at Harvard — that scholars should be funded only if their work conforms to a particular view of justice.

There’s a word for that idea: censorship. And it is just a modern-day form of McCarthyism.

Think about the irony: In the 1950s, the right wing was attempting to repress left-wing ideas. Today, on many campuses, it is liberals trying to repress conservative ideas, even as conservative faculty members are at risk of becoming an endangered species. And perhaps nowhere is that more true than here in the Ivy League.

In the 2012 presidential race, according to Federal Election Commission data, 96 percent of all campaign contributions from Ivy League faculty and employees went to Barack Obama. There was more disagreement among the old Soviet Politburo than there is among Ivy League donors.

That statistic should give us pause, because neither party has a monopoly on truth.

When 96 percent of Ivy League donors prefer one candidate to another, you have to wonder whether students are being exposed to the diversity of views that a great university should offer.

A university cannot be great if its faculty is politically homogenous. A liberal arts education must not be an education in the art of liberalism.

The role of universities is not to promote an ideology. It is to provide scholars and students with a neutral forum for researching and debating issues — without tipping the scales in one direction, or repressing unpopular views.

This spring, it has been disturbing to see a number of college commencement speakers withdraw or have their invitations rescinded after protests from students and — to me, shockingly — from senior faculty and administrators who should know better.

It happened at Brandeis, Haverford, Rutgers and Smith. Last year, it happened at Swarthmore and Johns Hopkins.

In each case, liberals silenced a voice — and denied an honorary degree — to individuals they deemed politically objectionable. That is an outrage and we must not let it continue.

If a university thinks twice before inviting a commencement speaker because of his or her politics, censorship and conformity — the mortal enemies of freedom — win out.

It’s not just commencement season when speakers are censored. Last fall, our police commissioner was invited to deliver a lecture at another Ivy League institution, but he was unable to do so because students shouted him down.

Isn’t the purpose of a university to stir discussion, not silence it? What were the students afraid of hearing?

Why did administrators not step in to prevent the mob from silencing speech?

And did anyone consider that it is morally and pedagogically wrong to deprive other students the chance to hear the speech?

Here is a short passage from John Stuart Mill’s “On Liberty”: “The peculiar evil of silencing the expression of an opinion is, that it is robbing the human race; posterity as well as the existing generation; those who dissent from the opinion, still more than those who hold it.”

He continued: “If the opinion is right, they are deprived of the opportunity of exchanging error for truth: if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error.”

Mill would’ve been horrified to learn of university students silencing the opinions of others. He would have been even more horrified that faculty members were often part of the commencement censorship campaigns.

For tenured faculty to silence speakers whose views they disagree with is the height of hypocrisy, especially when these protests happen in the Northeast — a bastion of self-professed liberal tolerance.

A university’s obligation is not to teach students what to think but to teach students how to think. And that requires listening to the other side, weighing arguments without prejudging them, and determining whether the other side might actually make some fair points.

If the faculty fails to do this, then it is the responsibility of the administration and governing body to step in and make it a priority. If they do not, if students graduate with ears and minds closed, the university has failed both the student and society.