BOOK REVIEW : Satire Misfires Without a Moral Center : THE BIG HYPE, <i> by Avery Corman,</i> Simon & Schuster, $19; 199 pages

Satire, says the New Columbia Encyclopedia in an unexpected bit of waffling, is “more easily recognized than defined.� Agreed: but it’s also true that satire is difficult to recognize these days, because outlandish exaggeration--once the principal arrow in the satirist’s quiver--is no longer an effective tool for ridicule.

When entertainers routinely become successful politicians, when journeyman baseball players earn a million dollars annually, when musicians prefer seeing their videos on television to hearing their songs on the radio, the satirist is hard put to come up with an exaggeration that won’t be taken as entirely plausible, perhaps even factual.

A year ago, for example, who would have conceived that the leading presidential candidate would be a man who has never held elective office?

Avery Corman’s “The Big Hype� is intended, as far as I can tell, as a satire on modern-day celebrityhood. Paul Brock, the New York-based television scriptwriter who narrates the book, has had enough of Hollywood; he wants to be a serious novelist, a writer who tells stories of depth and significance.

When a producer insists, for marketing reasons, that Brock’s made-for-TV movie script on playground basketball be changed--that the locale be moved from Harlem to Indiana, and the race of the players changed from black to white--Brock is understandably infuriated. He rededicates himself to finishing “Upward Mobility,� the novel he has worked on for years between money-making script assignments, and soon completes it.

The book, Brock tells us a number of times, is good: just about everyone to whom he sends the manuscript to declares it wonderful.

Brock’s agent sets up a book auction, four houses bid, and one offers $20,000 for the rights to publish the novel. It’s a good advance for supposedly literary fiction, but Brock is troubled because (as he tells his agent) “publishing is a business of self-fulfilling prophecies. And unless you get a really big advance and a big first printing and big advertising budget, your book isn’t going anywhere.�

Before accepting the offer Brock decides to talk with his old friend and former teen-age singing partner Mel Steiner, who has become a millionaire many times over as an entertainment manager.

Steiner reads Brock’s manuscript and loves it . . . indeed, considers “Upward Mobility� exceptionally marketable. Steiner decides to set up his own publishing company, hire a few editors, and offer Brock $100,000 for the book, his plan being to print 100,000 copies and spend another $100,000 on advertising.

Brock agrees to the deal, naturally, seeing himself not only legitimized as a novelist but liberated from television work. Brock soon discovers, however, that under Steiner’s management he has less time to write fiction than ever, for Steiner knows that the only way to guarantee the commercial success of “Upwardly Mobility� is to transform Brock into a celebrity.

He persuades Brock to churn out comic lyrics similar to the ones he wrote in his youth, hires an orchestra and an arranger to give Brock’s songs a professional sound, and then--using all his promotional wiles to make Brock a hot property--books him into Carnegie Hall.

Brock proves a quick study, his show is a success (due in part to the paid ringers in the audience), and Steiner’s stage-management ensures that Brock, now billed as “America’s Balladeer of the Middle Class,� becomes a national phenomenon. Brock even acts in a quickie theatrical film, which again proves successful--whereupon “Upward Mobility� becomes, on publication, a No. 1 bestseller.

What prevents “The Big Hype� from becoming satire, aside from the fact that Brock’s unintended career path seems altogether credible, is Brock himself. He’s a naive mensch , no more and no less: he enjoys his stardom, and appears only slightly bothered by the fact that the success of his book has nothing to do with its intrinsic merit.

Corman, best known for his novels “Kramer vs. Kramer� and “Oh, God!,� writes some good scenes, particularly between Steiner and Brock--at one point, when Brock is having trouble composing songs, the promoter tells him “ ‘start writing and if you can’t do it, we’ll send out for it�--but the book lacks the moral center that satire requires.

Brock never takes a stand, never says no and means it: he’s a nice-guy hack, which means the reader neither recoils from nor roots for his success.

Corman presumably wants Brock to be understood as a champion of literary culture, however ineffectual, but by the end of “The Big Hype� it’s hard to see him as anything but a fraud. He may want to be part of the solution, but Brock, at bottom, is part of the problem.