This contingency principle was demonstrated experimentally with a yeast culture that was maintained for many generations. Occasionally, a mutant strain would arise that increased reproductive success. These mutant strains would crowd out the formerly dominant strains. Samples of the most successful strains from the culture were taken across time. In later competition experiments, each strain would outcompete the immediately previously dominant type in a culture. However, some earlier isolates could outcompete strains that arose late in the experiment. (Would that we could put clinton in the Jefferson petri dish.) Competitive ability of a strain was always better than its previous type, but competitiveness in a general sense was not increasing. On April 25, 1978, in the Camelot Hotel in Little Rock, Ark., a nursing-home supervisor named Juanita Broaddrick was, she says, bitten and raped by the attorney general of Arkansas. As Joe Eszterhas describes it in ''American Rhapsody'': ''Finished, he got off the bed and put his pants back on. She was in shock, sobbing. He went to the door. He put his sunglasses on. He turned back and he looked at her. 'You better put some ice on that,' he said, and was gone.'' The alleged perp is now the president of these United States, and it's pretty clear that Joe Eszterhas thinks the story is true. (He says Broaddrick was ''as believable as anyone I'd ever seen on television,'' which is high praise in his idiom.) But, as he adds: ''It didn't matter. We were a tired people, tired of pornographic imagery on the evening news, tired of feeling we were mired in filth. This was the worst . . . and we didn't want to hear it.'' It all depends, here, on what the meaning of ''we'' is. For a start, who is Joe Eszterhas and how come he's our moral tutor in this fear-and-loathing tour of the Clinton sex scandals? If you've ever left a movie theater muttering to yourself, ''How'd that sucker ever get made?'' then you are probably familiar with Eszterhas's work. (I speak of ''Sliver,'' ''Showgirls,'' ''Jade'' and other insults.) Then again, if you've ever left a movie theater having had a slightly better time than you expected (''Music Box,'' ''F.I.S.T.''), then you have this hard-driving screenwriter to thank. Admit it, though, you probably know him from ''Basic Instinct.'' But since Hollywood's studio leadership has always been a reliable part of the pro-Clinton phalanx, you won't be seeing much of the Starr report on the silver screen. So when Eszterhas found himself consumed by the need to make sense of it all, his only recourse was a fact-based, ranting, rocking-and-rolling screed with none of the full-frontal scissored out. The ''we,'' it turns out, is the Who -- at least in the sense of ''My Generation.'' Eszterhas feels betrayed by Clinton, precisely because he once believed in him. Believed in him, that is, as the dope-smoking, draft-dodging adulterer of Mary Matalin's encapsulation. The boy-prince of the Rolling Stone set. ''One of us,'' in Jann Wenner's own unashamed words. So this is a long yell of protest from a professional hedonist who, faced with the ugliness of professionalized hedonism in the White House, doesn't care for the refraction of the mirror ... There are two or three chapters that rise above this, however, and that illustrate Eszterhas's hit-or-miss talent. He has acquired a real feel for the vulnerable, endearing, needy, hopeless character of Monica Lewinsky; the fat girl who was used and abused and who was only a fleck of evidence away from being denounced as a stalker and a mythomane. He fashions a near-brilliant evocation of the qualities of Vernon Jordan, the stoic and phlegmatic ally who knew exactly what he was doing, and who did it for a friend whose moral character was infinitely inferior to his own. And he is extremely funny about the shrink defenses that the first lady and other amateurs have proposed: ''A modern president, Bill Clinton was allegedly the victim of incest, pedophilia, child abuse, erotomania, sexual addiction, gambling addiction, alcohol addiction, rage addiction, wife beating, husband beating, grandfather beating, low self-esteem, jealousy and poverty. . . . There he was on television, this victim in chief, asking to be forgiven for something he wouldn't admit to having done.'' Finally -- and I curse myself for not noticing this at the time -- Eszterhas grabs the ironic coincidence of Richard Nixon's Monica. That's Monica Crowley, the trusting young intern and amanuensis who shared so much private time with the sage of Saddle River, N.J., and won his lonely, self-pitying and self-aggrandizing confidences only to make a book out of them. But at least Tricky Dick never told her that she might also share his life after Pat was gone... The book begins with a puzzle: How did the flower children fall for such a self-evident thug and opportunist? And it offers a possible hypothetical answer, which is that ''the Night Creature'' -- Nixon -- and his heirs and assigns could not ever possibly be allowed to be right about anything. When Eszterhas writes about Nixon, and his admirers like Lucianne Goldberg, he hits an overdrive button and summons the bat cave of purest evil. He hasn't read as much recent history as he thinks he has, or he would know that his forebears were mesmerized in precisely the same way to believe that Alger Hiss was framed. Thus does Nixon inherit an undeserved and posthumous victory. If by chance we ever elect a bent and unscrupulous Republican president, he or she will have a whole new thesaurus of excuses, public and ''private,'' with which to fend off impeachment. These ''bipartisan'' excuses will have been partly furnished by the ''nonjudgmental'' love generation. If Eszterhas had had the guts to face this fact, he could have written a book more like ''F.I.S.T.'' instead of ''Sliver.'' Meanwhile, and almost but not quite unbelievably, we await the president's comment on Juanita Broaddrick's allegation. Christopher Hitchens (on American Rhapsody), Basic Instinct