WASHINGTON -- Warning: The following contains extreme vulgarity by a candidate for the United States Senate.

In the razor-close and nationally important Senate race in Minnesota, Republican incumbent Norm Coleman is presented with a unique political problem. Should he raise in his ads the issue of comedian Al Franken's offensive vulgarity? Or would this risk a backlash against Coleman for coarsening the public conversation? Remember that when Ken Starr detailed Bill Clinton's most repulsive antics -- stained dresses and such -- it was Starr who was accused of sexual obsessiveness.

Franken's defenders explain that his edginess is the result of being a "satirist" -- a term he embraces. "My work, dare I say, is provocative, touching and funny," Franken has explained. "It sounds immodest, but I now have a brand name in political satire."

Satire has been called "punishment for those who deserve it." Writers from Erasmus to Jonathan Swift to George Orwell have used humor, irony and ridicule to expose the follies of the powerful, the failures of blind ideology and the comic weakness of human nature itself.

So what is Franken's "provocative, touching and funny" contribution to the genre? Consider his article in Playboy magazine titled "Porn-O-Rama!" in which he enthuses that it is an "exciting time for pornographers and for us, the consumers of pornography." The Internet, he explains, is a "terrific learning tool. For example, a couple of years ago, when he was 12, my son used the Internet for a sixth-grade report on bestiality. Joe was able to download some effective visual aids, which the other students in his class just loved." Franken goes on to relate a soft-core fantasy about women providing him with sex who were trained at the "Minnesota Institute of Titology."

Orwell would be so proud.

"Porn-O-Rama!" is a modern campaign document every voter should read -- the Federalist Papers of lifestyle liberalism. It has the literary sensibilities and moral seriousness of an awkward adolescent nerd publishing an underground newspaper to shock his way into campus popularity. But, in this case, the article was written in 2000 by a 48-year-old man.

Franken's "brand name" includes other highlights. In 2006, after a long monologue about a dog and its vomit, Franken impersonated the deceased Sen. Strom Thurmond as saying: "Yeah, I screwed a woman who was vomiting once." He once proposed a television sketch about a female CBS reporter being drugged and raped. He has suggested that his next book title might be "I F------ Hate Those Right-Wing Motherf------!" To an event hosted by the Feminist Majority Foundation in 1999, Franken told this thigh-slapper: "Why don't we focus on what Afghan women can do? They can cook, bear children and pray. As I recall, that was fine for our grandmothers."

Our popular culture, of course, violates even these expansive boundaries of tastelessness with regularity. We laugh at comedies featuring the C-word, and at cartoons of foul-mouthed third-graders. In the cause of relevance and realism, our common life is already decorated with excrement. Why should political discourse be any different?

For at least one reason: Because vulgarity is often the opposite of civility. This is not, of course, always true. I know a brilliant and large-hearted academic with roots in south Philly who uses the F-word with the frequency of "like" or "and." But the vulgarity of "The Jerry Springer Show" or misogynous rap music -- the cultural equivalents of Franken's political "satire" -- generally expresses contempt and cruelty. Franken is not content to disagree with Karl Rove; he calls him "human filth." He is not satisfied to criticize Ari Fleischer; Franken terms him a "chimp." The objects of Franken's humor -- including political opponents and women -- are not merely mocked but dehumanized. His trashiness is also nastiness. Rather than lampooning the emptiness and viciousness of our political discourse -- a proper role for satire -- Franken has powerfully reinforced those failures.

Some institutions must be more than a mirror to our culture, including families, religious communities and government. At its best, politics can offer examples of civility and generosity that challenge selfishness and prejudice -- the tradition so far embraced by both John McCain and Barack Obama. At the very least, politics should not actively push our culture toward vulgarity and viciousness. This is not prudery; it is a practical concern for the cooperation and mutual respect necessary in a functioning democracy. And it is hard to believe those causes would be served by a Sen. Franken.