What made Mark Sanford and David Letterman's public apologies work.There are many great things about not being a celebrity. One is that I am not dead of the celebu-flu that has been making the rounds. Another is that my apologies for sins, errors, and transgressions are all conducted in private.But for the famous, messing up requires a "my bad" loud enough for the whole world to hear. With the Mark Sanford apology-fest fresh in the collective mind, and David Letterman's Palin joke flap not far in the rear-view mirror, it's as good a time as any to look at a timeless tradition that no public figure wants to join.The problems with public apologies, typically, are the same as with private apologies. Many would-be mea culpas are really what Jon Stewart amusingly called a you-a culpa-instead of taking responsibility, bad apologizers toss it away like a live hand grenade. A classic example was Goldman Sachs chief Lloyd Blankfein's dodgy words "While we regret that we participated in the market euphoria and failed to raise a responsible voice, we are proud of the way our firm managed the risk it assumed on behalf of our client before and during the financial crisis." Matt Taibbi described it as "The Greatest Non-apology of All-time." Shifting responsibility this way is the not-so-secret ingredient of most non-apologies, as demonstrated by such tried and true tools of evasion as "Mistakes were made," "My comments were taken out of context," "I misinterpreted the rules," and the George Costanza-y "Was that wrong?"The now-notorious Mark Sanford did a far better job. His press conference was not merely a buffet of euphemism but a smorgasbord of sorriness, with specific apologies going out to his wife, children, staff, friends, and "people of faith across South Carolina." Though it turns out he left a few of the adulterous details out during that initial apology, he wasn't exactly evading the truth when he said, "...the bottom line is this: I have been unfaithful to my wife."University of Pennsylvania linguist Mark Liberman, who has written about public apologies before, was struck by something else: the jumbled nature of Sanford's speech. By email, Liberman wrote, "The most striking thing about his press conference and his late interview with the AP, I think, was how unpackaged they were, and therefore how messy and complex and human and incoherent they were. He ‘crossed lines' and ‘hurt people', but at the same time what he did was ‘his own prerogative', and he found his ‘soul mate', and ‘everybody's got their own value system'. Your standard political apology-wherever it is on the spectrum from ‘I was wrong, I'm sorry, I've learned my lesson' to ‘I'm sorry if anyone misunderstood me and took offense'-is at least a coherent package."So does incoherence imply sincerity? Maybe, because I feel a little bad for Sanford. A direct and organized statement prepared by speechwriters and P.R. gurus might get the point across more directly and sound more polished, but you can't script a genuine, messy, overflow of language and emotion. The soulmate talk isn't going to help Sanford's marriage, as William Saletan points out, but future apologizers who want to show their humanity could learn something from Sanford's refreshing word salad.Straight-up blame-accepting is never a bad way to go either. My lifelong love of David Letterman might color my perception, but I think his apology over the recent Sarah Palin flap-in which he inadvertently made a sexual joke about the 14-year-old Palin daughter-was spot on. Here's the money quote: "I told a bad joke. I told a joke that was beyond flawed, and my intent is completely meaningless compared to the perception. And since it was a joke I told, I feel that I need to do the right thing here and apologize for having told that joke. It's not your fault that it was misunderstood, it's my fault." That is pretty much the opposite of the "I'm sorry if you were offended" brand of non-apology.But even when public apologizers dodge blame like a falling flower pot-much like the lame-o private apologizers looked at by dating columnist Judy McGuire-the simple act of fessing up serves a purpose. That purpose was well-stated by linguist Geoff Nunberg, when he wrote of failed apologies, that "In the contemporary theater of contrition, the point of ritualistic public apologies isn't to demonstrate that an offender is really, truly sorry, but only that public opinion has the power to exact the expression of self-abnegation...."So pat yourself on the back, public opinion! Even if you treat the governors, television stars, and celububabes of the world as a mix of demigod, royalty, and genetic super-race, you at least have the power to make those celebs and politicians pretend to be sorry. These spectacles show that even the famous and/or gorgeous can't get away with everything all the time. To quote George Costanza again, "We're living in a society!" Public apologies keep the societal boat afloat, no matter how rough or polluted the waters. And sometimes, as with Sanford and Letterman, they're genuine, too.