David Letterman joined Tina Fey as a member of Sarah Palin's supporting cast last week. The Alaska governor, who is nothing if not resourceful, worked up an Oprah-esque feud with the television host over crude jokes Letterman told at Palin's expense. It was a good deal for both parties. Letterman got cheap laughs and attention; Palin got a fresh supply of umbrage—and attention.

Palin is both comfortable and adept at these tabloid squabbles—certainly more than she seems ever likely to be in a substantive environment. Parrying political opponents about policy, or responding to serious queries about the state of the world is just not what Palin does. Even her attacks on President Obama have a canned quality, something along the lines of ... "socialism, yadda yadda yadda." She leaves the details to Romney or Huckabee or perhaps next week's guest star.

By contrast, Palin seems genuinely animated by her contests with late-night comedians and she is always well-versed in the subject matter, which is, in order:

1. Sarah Palin;
2. What the cultural elite thinks of Sarah Palin;
3. What her supporters properly understand about what the cultural elite thinks of Sarah Palin;
4. Why Sarah Palin, and people who identify with Sarah Palin, are correct to resent the cultural elite for what it thinks of Sarah Palin.

With other politicians, comedians occasionally connect personality to policy dots: Cheney to "enhanced interrogation," Bush to the War on Terror, Obama to bailouts. The late-night focus on Palin is overwhelmingly personal for a reason: What else is there?

True, Letterman's joke about Palin's "slutty flight attendant" appearance would have been better targeted at John Edwards (who is far easier to imagine peddling "coffee, tea, or me"). But for all his self-destructive philandering and meticulous hair mussing, Edwards is still more than the sum of his narcissism. He mastered a difficult profession—trial law—and made an effort to understand at least one complex issue in American society—poverty.

Michigan Gov. Jennifer Granholm shares a more Palinesque profile. But the way their paths diverged is telling. Granholm, like Palin, was once a local beauty queen. She tried her hand at Hollywood and even appeared on The Dating Game in search of celebrity. But when her Hollywood dream went bust, Granholm attended UC Berkeley, applied herself, and graduated Phi Beta Kappa. She then went on to graduate with honors from Harvard Law School and build a career in law and politics.

Palin, on the other hand, still wants her celebrity straight, no chaser. After her beauty queen days, she tried television news. When that didn't pan out, there was never a period of buckling down. She just found a different route to the spotlight.

Palin knows she has pizazz, and she's sticking to it. As long as the conventions of television enable it, her skillful deployment of attitude—charm, hurt, outrage, flirtatiousness—can substitute for answers. It's hard to argue with the results: She has become a famous politician without actually mastering anything in particular.

That apparently includes politics itself. Palin's on-again, off-again, on-again saga at the Republican Party's June fundraiser in Washington suggests she doesn't even tend to the fundamentals of the trade absent a camera. After being offered the keynote speaking slot, she failed to confirm her acceptance and lost the high-profile job to Newt Gingrich. Then, after saying she wouldn't attend, she showed up for the dinner anyway, alienating party operatives with her unpredictability and blame-shifting. Her sparkle before the cameras covers for dysfunction offstage. What she brings to the table is not a public agenda or a talent for executing someone else's, but a self, via satellite and cable.

Ronald Reagan said "politics is just like show business." But Reagan used his showbiz shtick and ease before the camera to sell ideas—some of them consequential. Palin's showbiz is an endless, self-referential loop. Her media bashing—whether she's condemning Katie Couric for her rudimentary queries or extending the sell-by date on Letterman's put-downs—is simply a means to reflect attention back on herself. It's a cost-free way of holding the spotlight a little longer, a chance to say something attention-grabbing without actually saying anything that matters.

"When politicians ... have no other aim than to sell their leadership to the public," wrote Christopher Lasch in The Culture of Narcissism, "they deprive themselves of intelligible standards." The author was thinking of Nixon and Kennedy, two politicians at the dawn of the television age, for whom appearing "presidential" was a sometimes dangerous preoccupation. But Lasch also warned of "the contagion of unintelligibility" represented by politicians whose sole focus is themselves. Lasch didn't live to witness the prime time of Sarah Palin. But you have to admire his foresight. He saw her coming.