THERE ARE WORSE BOOKS than Fanny to read when you're 14 years old and babysitting and the late show is over. Problem is, most quasi-liberated housewives won't have them, being just with-it enough to fill their bookshelves with Erica Jong but not serious enough to challenge their minds with something truly bad, truly thought-provoking. The acceptable suburban raunch used to be The Happy Hooker, pure and wholesome smut, until women's lib hit the suburbs and Fear of Flying replaced the dog-eared Xaviera Hollander paperback because Erica had something important to say. This was smut with a message.

Never mind that no one quite figured out what it was. Some people pretended that Jong was harnessing women's repressed sexual drives, that she liberated The Woman from her self-image as passive, submissive receptor for The (horny) Man. Let's face it, Erica said, women are horny too, and they're even foul and raunchy and wicked and deliciously naughty sometimes. He's OK, She's OK--so let's all deal with it and come to grips with it and relax. The happy hooker didn't cut it because she was young and beautiful; Flying's Isadora, though, was over 30 and sort of dumpy, she had cellulite and body odor; the housewife could relate. So here was the message--anyone could be raunchy.

On the theory that there's some sort of vague socially redeeming value or at least some source of moral relief in that thought, Jong brings us Fanny, seven years after Isadora--the woman who admitted she was flattered when her lover felt at ease farting in her presence--slept her way to stardom in Fear of Flying. Some will hail Fanny as a reflection of Jong's maturation as a writer. In a sense, that analysis is correct--if Isadora was raunchy, then Fanny Hackabout-Jones is downright base.

Fanny is an even trashier novel than Flying or How to Save Your Own Life (1977), but that's not the most annoying thing about it. With Fanny, Jong backdates her heroine, capitalizing every other word in a futile attempt to satisfy on a literary level. Acclaiming her creation as a "mock-eighteenth-century novel," Jong writes the 490-odd-page story from Fanny's perspective in a brand of English that defies historical classification:

Belinda, 'tis true that the World is not form'd for the Benefit of Women, and oft' they must sacrifice their nice Principles in order to put Bread into their own Mouths and those of their Children; but I was ne'er so made as to be able to pretend Love of a loathsome Man for Hope of Gain, and it hath been my Experience that I have prosper'd nonetheless.

What is the purpose here? This seems to be dumpy, old Isadora Wing, dressed in pantaloons and a corset, belting out "I Am Woman" in Olde English.

ONE DIFFERENCE, though. While Isadora had justifiably noble intentions--that is, she at least had a sense of where she wanted to end up and thus consciously fought sexual victimization--Fanny merely goes along for the ride. Unlike her mundane prototype, this red-haired beauty doesn't really dig sexual freedom. On about page 250, we begin to lose track of the number of times Fanny has allowed herself to be raped, humiliated, used, and tortured. Not that our heroine doesn't get turned on once or twice; in fact, one message Jong seems to want to convey is that the once-innocent and always good-intentioned Fanny eventually breathes easily with her sexuality--enough, supposedly, to chronicle the sordid trysts for her daughter, the aforementioned Belinda (not surprisingly, Jong dedicates Fanny to her own daughter). And Jong does hit at some sort of admirable feminine tenacity that allows women to endure victimization. But what kind of goodness--either basic moral goodness or the good for Woman--is revealed in watching a woman repeatedly victimize herself?

In other words, where Flying pretends to moralize smut, Fanny purports to dignify outrage. That any woman should allow herself to be raped by her stepfather, humiliated by the homosexual lover of the man she herself loves, and abused by a gang of perverted female whores is hardly forgivable, let alone heroic or commendable. Add to this the confusion Jong creates by eventually granting Fanny her converted, no-longer-gay man and by indicting such distinguished writers as Alexander Pope and Jonathan Swift as Fanny's not-so-distinguished lovers. The result is a novel that, in self-consciously trying to infuse a message into vulgarity by shocking and disturbing, succeeds only in proving that Jong never really had anything important to say after all.

ALL THIS wouldn't matter so much if Fanny contained an intriguing plot or at least a reasonably interesting story line. But Jong doesn't seem to have time for these details. The message, the message. The book's jacket characterizes the insides as "highly entertaining" and "wildly funny"; could that refer to the page-and-a-half roster of eighteenth-century synonyms for "vagina"? Or maybe you consider reading about 12 men who gang-rape an innocent victim wildly funny.

Fear of Flying was not a good novel insofar as it told us something we already knew in a way that exaggerated the unimportant, and thereby obscured some of the more significant aspects of the feminist movement. But at least it was short, the smut was relatively all-American, and it exuded a certain honesty about the shortcomings and strengths of the average modern woman. Fanny--a novel that pretends to relate the true biography of John Cleland's Fanny Hill but doesn't begin to compare with that work--refuses to preserve even the integrity of its own purpose. When Fanny dives headfirst into her self-deprecating adventures, she carries any important messages about feminism with her. Jong's latest is smut, after all--but smut with the stink of moral intentions gone bad.