Stephen Colbert’s “testimony” before Congress last week was a clear sign that ironic rot (if you’ve got a better term, let me know) is sinking into the foundation of our political system.

Irony or post-irony or ironic post-whatever has been metastasizing through the culture for decades. The most famous example was “Seinfeld,” a hilarious show that was famously “about nothing” and much-derided by earnest writers on the left and right for its detached mockery of any deeply held principle or conviction.

But it hardly began with “Seinfeld.” David Letterman launched a talk show that made fun of talk shows. Before that, “Saturday Night Live” crafted brilliant fake commercials and newscasts (which, sadly, are the only reliably funny parts of the show these days).

In the 1990s, Washington fell in love with Hollywood in an unprecedented way. In countless films, politicians, reporters and pundits played themselves. There was also an influential, and occasionally funny, sitcom called “Murphy Brown” that jumped back and forth from make-believe to reality. Things got particularly confusing when Vice President Dan Quayle criticized the show for glamorizing out-of-wedlock birth, and the show’s creators responded by having the fictional Murphy Brown whine about personal attacks on her lifestyle.

Things got outright weird with the creation of “The Daily Show,” a fake news program hosted by Jon Stewart since 1999 that often provides some of the best (and occasionally the worst) criticism of American politics and is revered on the left as somehow newsier than news. For what it’s worth, a senior Republican congressmen told me that a “Daily Show” piece on the GOP “Pledge to America” was the only one that drew blood.

“The Daily Show” begat “The Colbert Report,” in which Colbert plays a jingoistic, know-it-all, borderline bigot whose standard for veracity can be summarized with the word “truthiness.”

In other words, he pretends to be what many liberals claim Bill O'Reilly is. That’s the joke, get it?

It was this Stephen Colbert who was invited to testify before a House judiciary subcommittee on immigration and labor. It was an excruciatingly inappropriate spectacle. “This is America,” Colbert inveighed. “I don’t want a tomato picked by a Mexican.”

But who, exactly, is Colbert parodying here? O'Reilly doesn’t talk like that. Nor does Sean Hannity or any of the usual targets Colbert’s supposed to be lampooning. The real upshot of Colbert’s shtick is that he’s mocking people who disagree with him – or with the left-wing base of the Democratic Party – on the complicated issue of immigration.

This was made abundantly clear by the sober testimony of Carol Swain, a Vanderbilt University professor of law and political science, who argued quite effectively that a steady flow of cheap migrant labor depresses wages for poor blacks and other American workers while keeping working conditions grim.

Though Colbert would obviously deny it, his testimony amounted to calling Swain – an African-American woman of very humble background – an ignorant bigot, because her analysis runs counter to the liberal party line.

Colbert’s defenders point to the fact that other celebrities have testified before Congress. “I would like to point out,” Rep. Judy Chu (D-Calif.) noted during the hearing, “that in the past the Republicans have had witnesses such as Loretta Swit, who played ‘Hot Lips’ Houlihan from ‘MASH,’ to testify on crush videos.” True enough. But she didn’t testify as “Hot Lips.”

Colbert’s testimony reduced the topic to a black-and-white issue in which people on the other side are fools or bigots worthy of cheap mockery. I thought the whole point of Colbert was to stand against that sort of thing by making fun of it, not by doing it. Are our politics really improved by making congressional hearings even more of a joke? Were they truthiness-deficient?

On Oct. 30, Colbert’s “March to Keep Fear Alive” will join Stewart’s “Rally to Restore Sanity” on the National Mall. They will rationalize the stunts as send-ups and putdowns of all that is wrong with our politics. But by slowly degenerating from satire into plain old mockery, these guys are slowly becoming too-clever-by-half versions of the very people they claim to deplore.

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