If you've encountered any mention of The Lifespan of a Fact by John D'Agata and Jim Fingal, you've probably heard that it's about one guy (D'Agata) who wrote an essay about a teenager who killed himself in Las Vegas, and another guy (Fingal) who was hired to fact-check that essay and discovered that a lot of it was made up. The book contains the essay and a dialogue between the two men, with D'Agata defending his artistic license and Fingal obsessively seeking absolutely verifiable truth.

That's an accurate enough description as far as it goes, but it doesn't go very far. It tames the thorns and brambles, it avoids the jack-in-the-box paradoxes, it herds and declaws the mischievous cats lurking in between the lines.

One of the elements of The Lifespan of a Fact that ought to be front and center in any review is that the book is not an unmediated report of a particularly scrupulous fact-checking session. D'Agata and Fingal met when Fingal was an intern at The Believer assigned to fact-check D'Agata's essay, yes, but partway through the process they decided their disagreements might make for an interesting book, and so they spent quite a while shaping that conversation, creating personas for themselves and employing those personas in a scripted dialogue. D'Agata said in a recent interview, "I think of the form of the exchange between Jim and me as an exaggerated farce."

If we read the voices in the book as characters, The Lifespan of a Fact often plays as an Odd Couple-style comedy. The character of John starts out a bit aloof and put off, annoyed that what he considered an imaginative, artistic essay is being treated like a piece of journalistic reportage, while the character of Jim seems like an overexcited intern determined to make his boss (The Editor, who has a few lines) happy. As the characters dig in their heels, they take their arguments about as far as they can go. Jim becomes fanatically obsessed with verifying absolutely everything, while John is reduced to vulgar insults once he realizes that the best of his arguments have only caused Jim to seek ever more ridiculous levels of verification. It's a marvelous pas de deux of stubbornness and obsession.

The structure of the book, both visually and narratively, is more complex than it might seem at a quick glance. The pages present D'Agata's essay draft in blocks of relatively large type in the middle of each page, with most pages having about 150 words of the essay text in the center, though some have considerably more and others considerably less. What determines the size of the text in the center is the length of Fingal's—or, rather, Jim's, since we're talking about a character—statements about that text, for the central text blocks are surrounded by smaller type in either red or black. The black text represents facts Jim has been able to verify (with explanation) and the red text offers his ideas about the facts he finds unverifiable or inaccurate, and, sometimes, John's response. Most of the pages have far more marginalia than essay text.

By the end, Jim's marginalia expands beyond D'Agata's essay, leaving a blank hole in the middle of the last two pages. (It's like an episode of Mystery Science Theatre 3000 where the characters can't stop talking even though the movie has finished.) If you give yourself over to the book, this ending is surprisingly powerful, because the character of Jim has by this point become so obsessed with verifying all of the factual truth of the suicide that he switches from fact-checking D'Agata's essay to attacking the details of the official Coroner's Report, finding discrepancies and inaccuracies equal to many of the discrepancies and inaccuracies he found in D'Agata's essay. "So I guess I have to wonder," he says as he winds down his analysis, "that if this one fact in the only existing document that officially records Levi Presley's death is this significantly unreliable, to what extent can we trust the reliability of the Coroner's Report as a whole . . . ?" This brings the questions raised throughout the book to a newly serious level, because previously Jim had been relying on the official documents as weapons against John. His sense of the entire situation is shaken now because it seems his faith was, by his estimate, misplaced. He has finished counting and categorizing every last tree, and now he sees there is a forest behind him. Even if he could verify absolutely everything, even if John's opinions about art and truth changed, even if the essay were edited to conform absolutely to only what can be 100% known, the one most important fact would not change: Levi Presley is dead.

The Lifespan of a Fact becomes, in its last page, not just a tricksy debate about facts and truth, but an unsettling exploration of art and mortality.

The dialogue crescendos to a few climaxes, with John finally refusing to cooperate any longer as Jim gets more and more obsessed, and then both characters cool down a bit and have a five-page discussion of what really bugs them about the other's position. The essay in the center becomes overwhelmed by the marginalia here, strangled down so that shards of one sentence are spread across the five pages. Finally, the characters reach a sort of détente, and John goes away, leaving Jim to deal with the final sequence of the essay, a description of Levi Presley's last moments as he ascends to the observation deck of the Stratosphere Hotel and Casino, climbs over the railings, and plunges about 850 feet for eight seconds to his death.

Commentators who haven't read the book seem to enjoy getting huffy about it, with many extrapolating from some of the reviews that D'Agata turned Levi Presley into a fictional character and thus despoiled his memory and dishonored his family and proved himself to be evil incarnate on Earth. This is not true. Mostly, D'Agata seems to have fudged some numbers, changed some names, and massaged some quotes. He seems to have simplified some contextual facts about suicide and Las Vegas. He seems to have relied on memory for many of his interviews rather than transcripts.

I say "seems" because I have not verified all of the verifications offered by the character of Jim. I have no idea if the box of notes and research materials Jim refers to having received from John corresponds to a real box received by the real Jim Fingal. I know little about the geography of Las Vegas, little about the statistics for suicide and death in the United States, nothing about coroners' reports.

If it turned out that most of what the character of Jim offers as facts were, instead, imaginings, and most of what the character of John is supposed to have made up was, instead, actually true . . . would it matter to me as a reader?

I don't know.

That's one of the effects of this book—by making the characters of Jim and John rather extreme proponents of their views, it forces readers into the middle and destabilizes our assumptions about what we know and value.

You don't have to have read interviews with the writers to suspect that The Lifespan of a Fact is not a documentary record of a particularly arduous fact-checking session. (Anyone who does think it is would probably also think Pale Fire is a scholarly annotation of an obscure poem.) The book is a construct and a provocation, an embodiment of its own argument. It forces us as readers to confront our expectations about genre and truth, and to consider what labels such as "nonfiction" hide. It makes us think about the facts we value, the facts we insist on. (For instance, while I was not bothered by many of D'Agata's supposed changes of fact, I was horrified that he—or, at least, the character of John—would silently change quotations from people and texts without qualm.) Ultimately, amidst everything else it is doing, The Lifespan of a Fact forces us to reflect on how we assemble an idea of life from all the possible items that sprout in every second.

If there were justice in the universe, The Lifespan of a Fact would be made into a movie by Werner Herzog, who has made narrative films (Aguirre, The Wrath of God; Fitzcarraldo, etc.) and documentaries (Grizzly Man, The Cave of Forgotten Dreams, etc.), and who never lets facts get in the way of truth. His documentary Gesualdo: Death for Five Voices tells the story of a real late-Renaissance composer and murderer through mostly fictional moments, with no indication that there is anything fictional at all. Fata Morgana, Lessons of Darkness, and The Wild Blue Yonder present documentary footage with fictional narration (obviously so in the latter two, as they are science fiction stories). Even in his more factually based documentaries, Herzog has no compunction about making stuff up because it feels right—in Little Dieter Needs to Fly, for instance, he had the subject of the documentary, Dieter Dengler, display obsessive compulsions that he did not have. (Herzog later made Dieter Dengler's story into a feature film, Rescue Dawn, with Christian Bale playing Dengler.)

The Lifespan of a Fact vividly demonstrates the differences between what Herzog calls "the accountant's truth" versus the "ecstatic truth."

In his "Minnesota Declaration," Herzog said, "Filmmakers of Cinéma Vérité resemble tourists who take pictures amid ancient ruins of facts." John D'Agata might say the same thing about virulent fact-checkers.

While everyone will have different levels of tolerance for such views, it would be a mistake to say that either Herzog or D'Agata just wants a license to lazily make everything up and call it nonfiction or documentary. (Neither cares much for either term, actually.) To pretend that all-encompassing binary terms such as "fiction" and "nonfiction" can dispel all ontological problems is a delusion—worse, an evasion.

Some facts really do matter, as Herzog and D'Agata admit. D'Agata lets Levi Presley's life and death stand unchanged in any significant way, unfictionalized, but Presley's motives remain inaccessible. D'Agata does not pretend that we can understand what the boy thought and felt that day as he made his way toward death. He gets to the most meaningful truth for those of us who will likely never know Presley's family, maybe never even visit Las Vegas—the truth that one of the most vexing and painful facts of suicide is its unknowability for the survivors. This is the point the character of Jim reaches by the end of The Lifespan of a Fact. His quest for verification began as a simple job, but it became a quest to assemble all the details so that, perhaps, they could provide a meaning to Levi Presley's death and, by extension, to the mystery of self-annihilation. Perhaps, Jim seems to think, if we get everything verified and in just the right order, we'll know more than we did when we began.

But we never do.