In an essay published in the November 1995 Harper’s, Katie Roiphe denounced “Push” and the current vogue of “incest fiction” as “politically trendy.” Roiphe treated the theme as an odd, anomalous bubble — a hiccup in the stately progress of American fiction resulting from “the alchemy of academia and politics” combined with “a certain pop-feminist sensibility” that created “a mainstream fascination with victims of all kinds.” She’s only partly right, as usual (Roiphe sometimes seems like a stealth weapon of the politically correct, her attacks on them are so half-cocked and easily refuted). In actuality, incest fiction is simply the fattest thread in a braid of trends that add up to the memoirization of American fiction.

More presciently, the New York Times Sunday Magazine last month announced that this is the “Age of The Literary Memoir,” presenting samples from 12 writers and noting the ascension of Mary Karr’s “The Liar’s Club,” Susanna Kaysen’s “Girl, Interrupted” and William Styron’s “Darkness Visible” to the bestseller lists. “The novelist writes disguised autobiography,” James Atlas states in his introduction. “The memoirist cuts to the chase.” Sapphire, whose vivid poetry testifies to a past of poverty and sexual abuse, is, like so many American authors, giving us fiction that seems to approximate her own experience, just as Dorothy Allison did with “Bastard Out of Carolina.”

But novelists — except in the very broadest sense — haven’t always relied on “disguised autobiography.” From Dickens and Eliot to Melville and Faulkner, they took small bits and pieces of their lives and then went on to construct fictions both vast and deep from that underappreciated faculty, the imagination. American literary fiction, and fiction readers, have become cautious. We’ve grown to undervalue or even mistrust the very authority of an author who ventures too far from her own experience. As a result, we’ve got a crop of current work that focuses relentlessly on the domestic circle — on childhood, in particular, but also sex and marriage. Incest is merely the biggest, the most momentous and dramatic, event that can happen on that front. We are feeding our appetite for terrible secrets, for cataclysm and stark polarities of good and evil, on the strongest meat that can be found in the familial cupboard.

While the ancient Greeks used incest narratives to talk about the merciless vagaries of fate, the incest story as we tell it (a parent, usually the father, molesting the protagonist, usually a girl) flexibly lends itself to two of America’s favorite plots: the gothic and the rags-to-riches Horatio Alger inspirational. Both “The Color Purple” and “Push” follow the latter model. The heroines of both books scrabble up from the emotional rags of abuse to the riches of education, pious sisterhood and economic self-reliance. Other incest narratives (more often used by white writers — Jane Smiley’s “A Thousand Acres” is an example) move down instead of up, starting with a present that ought to be rosy, but inexplicably isn’t, and eventually unearthing the horrid “dark secret” that twisted everything at the root, all in classic gothic style.

As a plot device, therefore, incest is both venerable and versatile, and until the recent glut of incest fiction it still had the capacity to shock. You can count on it to unite virtually all readers in revulsion: Everyone agrees that hurting a child, especially sexually, is the ultimate, inexcusable wrong. But Roiphe errs in assuming that novelists linger in this territory simply because it’s a “hot subject” or “modish plot twist” with “commercial potential,” eventually to be replaced by another gimmick. The fixation is less opportunistic than agoraphobic. Outside, in the world beyond the family, lie fictional challenges that few American literary writers feel equal to, and it’s not clear that readers want to see them venture into that territory, either.

In 1989, Tom Wolfe published, also in Harper’s, a “literary manifesto” for a “new social novel,” one that would attempt to describe the times we inhabit. Blithely self-congratulatory, Wolfe’s essay held up his own book, “The Bonfire of the Vanities,” as an exemplar. Denouncing a strain of cerebral, experimental fiction (practiced by male academics like John Barth and John Gardner) that was already in decline, Wolfe called for more “realism” in the novel in order to address the huge demographic changes transforming American cities.

Wolfe got what he asked for, but not in anything like the form he set up as a paragon. Realism is precisely the imperative that guides large portions of the literary scene, a realism grounded on the maxim “write what you know” and faithful to the notion that a novelist’s authority ought not to extend much beyond the boundaries of her autobiography. Wolfe, the famous spokesman of New Journalism, advocated that fiction writers develop their reportorial research skills in order to depict people different from themselves. But try to imagine Wolfe getting away with writing from the point of view of a character like Precious Jones, the narrator of “Push.” The idea is ludicrous; only Wolfe would be arrogant enough to attempt it, and that breezy, oblivious presumption itself would probably doom him to artistic failure.

Furthermore, if Wolfe were to write from the perspective of an illiterate black teenaged mother and incest victim — however skillfully — a flock of shrieking “multicultural” critics would descend upon his head before the ink had dried. Critics like bell hooks have made a profession of scolding white artists of all stripes for incorporating any aspect of black culture into their work, accusing them of “appropriation” (i.e., stealing). This amounts to more than just the ravings of the identity politics brigade (it has long been a commonplace complaint about Elvis Presley among white rock critics, for example). There is a culturally diffused wariness regarding fiction itself, if by “fiction” we mean a creation primarily of the imagination.

Some novelists may flinch from the tongue-lashings administered by the likes of hooks, but most are probably responding to this generalized uneasiness. Why read Pearl S. Buck when you can have Amy Tan, who sports the imprimatur of ethnic validity? (Buck, incidentally, spent much more of her life in China than Tan has.) We have become increasingly obsessed with authenticity. Even a sliver of literary sensationalism like Susanna Moore’s “In the Cut” gets promoted with intimations of autobiography. The book’s publicity campaign emphasized that Moore, an elegant bohemian socialite, conceived of the novel while hanging out with the homicide division of the NYPD as research. “In the Cut” is the story of an elegant bohemian socialite who has a kinky affair with a homicide cop. Please do make the connection; Moore’s publisher would want you to.

Novelists who write autobiographical fiction are often congratulated for their courage, their audacity in “speaking the truth,” usually about family secrets or sex. Memoirists, however, can always one-up them when it comes to self-revelation, and the reading public’s thirst for books stamped with the guarantee of “True Story” (however debatable that claim) — preferably with a juicy lode of photographic evidence running through the center — seems to be unquenchable. (Pulitzer Prize winner Carol Shields tweaked it by including a mix of scavenged historical photos and snapshots of her own children in the entirely fictional “Stone Diaries.”)

Novelists may be in danger of obsolescence unless they do something really brave, like break out of the straitjacket of autobiography and imagine themselves into the skins and psyches of a wide range of characters. Ironically, it’s white men who have been most forced to do this: Unless they’ve been mistreated by their parents like Tobias and Geoffrey Wolff, they don’t have a life story deemed interesting enough for confessional fiction. Young Turks such as David Foster Wallace, William Vollman (when he’s not wallowing in Charles Bukowski-land) and Jonathan Franzen — although given to excessive public lament about the crisis of their art — are trying to explore new terrain. That takes a certain bravado, which in turn tends to put many Americans off (we like our writers modest), and these novelists are often branded as too clever or flashy. Portraying the media- and advertising-saturated nature of contemporary life without succumbing to the flimsiness and superficiality of mass culture (cf., Douglas Coupland) may present them with their biggest challenge.

In fact, fear of vulgarity may be as much to blame for literary fiction’s pervasive timidity as the pernicious influence of identity politics. Stephen King and Anne Rice don’t rule the bestseller lists by writing disguised autobiography. Inventive fiction has been ceded to commercial novelists (who have no shame) and foreigners (Salman Rushdie, Milan Kundera, Umberto Eco, the Latin American Magic Realists) who aren’t expected to conform to our puritanical notions of high art — and who are permitted the uppitiness of summing up their own cultures.

With so many forces — literary fashion, reader tastes, political anxieties and the low-brow taint of pop — marshaled against it, the big, ambitious literary novel Wolfe once championed may be a long time coming, if at all. The PR on Sapphire’s “Push” claims the novel is “already causing a furor,” but that’s hard to believe — unless Roiphe’s unjustifiably snarky references to it in Harper’s qualify as a “furor.” Once upon a time, a mediocre novel like “The Color Purple” earned plenty of points for taking on a taboo and offering us a fresh viewpoint. For all Sapphire’s passion and accomplishment, she’s serving us a plate of leftovers.