Yes, yes, we know: Free speech is enshrined in the First Amendment and sacrosanct in the political culture. Inherent rationality in public discourse would break down, Americans are told since grade school, were the right of individuals to express their chosen philosophies to be abridged.

Yet an unprecedentedly sweeping attack on freedom of expression was launched last week when a celebration scheduled for Feb. 11 — an Iranian holiday marking the 26th anniversary of the Islamic revolution and the fall of the government of Shah Mohammed Reza Pahlavi in 1979 — was canceled by operators of the Bethesda Conference Center, where the event was to be held.

The Bethesda Conference Center, outside Washington, was to play host to roughly 1000 guests, mostly Iranian Americans. A spokesman for the center said that the event was canceled when officials “realized” that it was “illegal to do business with Iran” and that they will “be taking steps” to prevent similar bookings in the future.

This column is not holding a brief here for the Islamic revolution, but a brief for free speech.

The issue, in other words, is not about whether it is right for Iranian exiles to put on a function like that in the United States, but whether they have a right to it — a right to exercise their first Amendment freedoms of speech and association.

Where do you draw the line when you proceed to curtail the right of citizens to say what is on their minds — because their views are unpopular or even repugnant?

There is no line to draw here. The law is clear on that.

Outside hate speech that incites violence against others, especially minorities, no one in government, in the world of academe or in public discourse has the authority to limit how you express your thoughts about any pet issue of your choice.

There are atheists and racists who freely hold annual gatherings around the United States, the former to assert what they believe and the latter to prove that people of color are genetically inferior, as there are Nazis and Baptists who will tell you from their public podiums, respectively, that Hitler was a great man and that those men — sinners one and all — who do not convert to Baptism in the now will fry in everlasting hell in the hereafter.

And there are all sorts of kooky activists in every state of the Union, with a political axe to grind or an ideological agenda to promote, who feel free to run around and tell you, without fear of retribution or the threat of censorship, what their views are on issues as diverse as abortion, the Middle East, marijuana laws, the right to bear arms, Sept. 11, and the rest of it.

Back in 1964, at the height of the civil rights movement, when an Alabama court, in a case called “New York Times v. Sullivan,” ruled against a political advertisement that supported civil rights groups in the South, the case finally went to the Supreme Court. Justice William Brennan, writing for a unanimous court, said the Alabama judgment was a violation of the “the profound national commitment to the principle that debate on public issues should be uninhibited, robust, and wide-open, and that it may well include vehement, caustic, and sometimes unpleasantly sharp attacks on government and public officials.”

That was not all, for Brennan added that “neither factual error nor defamatory content suffices to remove the constitutional shield” that protects free speech.

Where, then, I ask, do we draw the line when it comes to freedom of expression?

Do we selectively abridge one group’s, but not another group’s, right to speak out and speak up because we find the views of the former offensive to, and the views of the latter in accord with, our own? Do we, in this case, deny Iranian Americans their right to free assembly in Bethesda because they come from a country that, according to President Bush in his State of the Union last Wednesday, “remains the world’s primary state sponsor of terror, pursuing nuclear weapons while depriving its people of the freedom they seek and deserve”?

Do we shut them up because these views do not conform to our own social, ideological and intellectual values, or because, say, they are wrong?

I don’t think that we are, by any stretch of the imagination — Patriot Act notwithstanding — going back to the depredations of the McCarthyism of the 1950s, the Red Scare of the 1920s or the Alien and Sedition Acts of the 1790s, but we are trampling on some pretty sacrosanct freedoms here.

And we are doing it selectively — for the speech police, as it were, is called in to intervene only when those, whose philosophies are at odds with ours, are involved.

Note this: Last week, at a panel discussion in San Diego, Lt. Gen. James N. Mattis, who commanded the first Marine Division in the 2003 invasion of Iraq, told his audience that “it was a lot of fun” to shoot the enemy. He was quoted in the Washington Post as saying: “Actually, it’s a lot of fun to fight ... It’s fun to shoot some people. I’ll be right up front with you, I like brawling. You go go into Afghanistan; you got guys who slap women around for five years because they didn’t wear a veil. You know, guys like that ain’t got no manhood left anyway. So It’s a hell of a lot of fun to shoot them”

The three-star general was simply told by the commandant of the Marine Corps to “choose his words more carefully”. Case closed. And I agree, for even a buffoon has a right to express his ideas in public.

Yet, when Ward Churchill, a Native American tenured professor, who teaches American Indian Studies at the University of Colorado, was discovered recently to have made some inflammatory remarks about Sept. 11, in a commentary piece he had dashed off within hours of the attacks, he not only triggered a national outcry but faced dismissal by his university’s Board of Regents, an elected body dominated by conservatives. (The legal process required to fire a tenured professor is long and complicated, so Churchill is not likely to go on food stamps any time real soon.)

When free speech is curtailed, or rationed out selectively, two victims fall by the way side: The very language we speak, that will now no longer grow and freshen, and the quick of the social spirit, that will now no longer convey humane order in our lives.

I say we should have let those cranks at the Bethesda Conference Center celebrate their wretched event, turning political reality on its head in order to say white where there is black. Or whatever the devil they wanted to say. No one had the right to cut off their right to speak and assemble freely. Alas, someone nevertheless did.