If a book is good, if it’s artful, entertaining, and informative, should it matter who the author is? Once upon a time, many readers would have said no. It was a long-standing protocol of book appreciation to consider things like the gender, sexuality, ethnicity, personal vices, personal virtues (if any), and prior reputation of the author irrelevant to a book’s merits. You could disapprove of a writer’s politics and prejudices if they showed up in the text; otherwise, they were customarily bracketed off.

When people had an issue with the author, it was because they felt that he or she had violated what is known in narratology as the “autobiographical pact.” This is the tacit understanding that the person whose name is on the cover is identical to the narrator, the “I,” of the text. The pact obviously governs our expectations about memoirs, but it extends in a more general way to books in which the speaker or the protagonist is presented as a fictionalized version of the author (so-called “autofiction”), and it extends even to straight-up fiction: if the name on the cover seriously misleads us about the identity of the author, we can feel we have been taken in.

There have always been writers who cheated on the pact. A case most people know is that of James Frey’s 2003 memoir of recovery from addiction to alcohol and crack cocaine, “A Million Little Pieces.” The book was hugely popular, but it turned out to be partly fabricated, something Frey was forced to admit on television under the interrogation of Oprah Winfrey, who had chosen “A Million Little Pieces” for her book club and thereby made it a best-seller.

The auto-da-fé took place in 2006, and the publicity turned Frey’s name into a synonym for memoir fraud. At the time, Frey’s exposure and humiliation struck many people as just deserts. But there have been at least three traditional lines of defense for books like “A Million Little Pieces.”

One, used for popular autobiographies whose strict veracity has been questioned, such as “The Autobiography of Malcolm X” or “I, Rigoberta Menchú,” is the surrogacy defense. This is the theory that, although a particular event recounted in the book may not have happened to the author, it happened to someone. Such a book, then, is really the life story of a group. The memoirist should be understood as representing all African-American men in the era of Jim Crow, or all indigenous people in Guatemala. Experiences common to the group are therefore legitimately represented as happening to a single, quasi-allegorical figure.

Another strategy is the higher-truth defense. This is the argument that fabrications and exaggerations in books like these are in the service of more fully conveying “what it is really like” to be Guatemalan or in recovery or whatever the theme of the life story happens to be. “A Million Little Pieces” tries to capture the experience of recovering from addiction. Readers don’t care whether these things literally happened to James Frey, because they didn’t buy the book to find out about James Frey. They bought it to learn about addiction and recovery. James Frey’s job as a writer is only to convey that experience.

And then there is what might be called the literature professor’s defense. This is the argument that the distinction between fact and fiction, although it may appear fundamental, is a fairly recent development in the history of writing, only two or three centuries old. Along with that distinction came the practice of putting the author’s name on a book, and along with both of those came the ideology of authenticity—the belief that literary expression must be genuine and original.

The literature professor’s point is that placing social value on concepts like authenticity is an invitation to manufacture them. A certain style of writing can come across as more authentic, and this can help a book gain status in the literary marketplace. Why did many readers become infatuated with Karl Ove Knausgaard’s multivolume work “My Struggle”? Because the books read as authentic—so powerfully authentic that, at this point, if Knausgaard were to tell everyone he made it all up, no one would believe him.

“My Struggle” performs authenticity beautifully, and the literature professor asks why we should want anything more than that. Forget about whether the story “truly” happened to some “real” person—a philosophical rabbit hole. We are judging words on a page. Either they work for us or they don’t.

Literature professors were comfortable with this kind of argument because they thought of identity as something that was hybrid, intersubjective, performed. The idea that you could draw a straight line from the text back to some fixed and knowable entity called “the author” was naïve. So was the idea that you could draw a straight line from the text outward to some external stuff called “reality.” The fact/fiction distinction was unstable, always contested, and so on.

But that was then, and this, to put it mildly, is now. The rules have changed. The ethics of authorship are completely different. In academic discourse, hybridity is out; intersectionality is in. People are imagined as the sum of their race, gender, sexuality, ableness, and other identities. Individuals not only bear the entire history of these identities; they “own” them. A person who is not defined by them cannot tell the world what it is like to be a person who is. If you were not born it, you should not perform it.

In the culture industries, the identity and the personal history of artists have become unbracketed. Critics worry about whether it’s still ethical to admire Woody Allen’s movies or Louis C.K.’s standup routines. And the view that certain characters are out of bounds for novelists who don’t share their identities, although it seems to contradict a basic premise of fiction writing, has penetrated the world of publishing.

As for the public discourse, it is almost completely corrupted by mendacity. The political lie has achieved a kind of unholy immunity, such that when liars are caught they no longer complain that they have been misunderstood. They “double down” on the lie as shamelessly as possible. An accepted way to respond to someone who accuses you of lying is to accuse that person of lying, an invitation for people to choose the falsehoods that suit them, since it’s all fake anyway. In these circumstances, it would be nice to put some bones back into the old fact/fiction distinction.

This is where Christopher L. Miller’s smart and engaging study, “Impostors: Literary Hoaxes and Cultural Authenticity” (Chicago), enters the conversation. Miller is a literature professor at Yale, so he has been around the “death of the author”/“there is no ‘outside the text’ ” block a few times. He says that he was drawn to the subject of hoaxes because he was interested in the games they play with readers’ expectations—that is, for old-fashioned literature-professor reasons.

But as he was working on the book the world turned, and he realized that fakery is no longer just a classroom sport. “It is harder to see the fun in deception when the fate of the world seems to depend on resisting lies, ‘alternative facts,’ and ‘fake news,’ ” as he puts it. It seems to have taken the election of a man who is the personification of perspectivalism to reset the ethical calibrations of literary criticism.