Everybody is wrong in Philip Roth’s American Pastoral. They start out wrong. They misjudge those around them and become hopelessly confused. The characters’ lives are a mess; they must make a home in the ruins. But then, “getting people right is not what living is about anyway,” Roth (in the guise of his fictional alter-ego Nathan Zuckerman) reminds us. “It’s getting them wrong that is living, getting them wrong and wrong and wrong and then, on careful consideration, getting them wrong again. That’s how we know we’re alive: we’re wrong.”

All of which should make Ewan McGregor’s film version of American Pastoral the most pulsatingly alive piece of cinema we’ll witness all year. The casting is wrong. The handling is bungled. The tone is off-key. It should at least possess a certain breakneck panache; a car-crash fascination. But no – American Pastoral’s succession of wrong turns only serves to steer it into a creative cul-de-sac. The result, as Variety put it, is a film “as flat and strangled as Philip Roth’s novel is furious and expansive”.

Few authors have been quite so ill-served by the film industry as Roth, whose ruminative, proselytizing, deeply felt writing style appears to set all manner of traps for the Hollywood scriptwriter. The 1969 adaptation of Goodbye Columbus remains a decent, dogged pass at the material. Since then, the films have verged from the calamitous (Portnoy’s Complaint, The Human Stain) to the leadenly deferential (The Humbling, Indignation). So it’s no surprise that American Pastoral (arguably the finest American novel of the past 20 years) should become a timid, mithering non-drama, in which McGregor directs himself as the tragic Swede Levov, picking his way through the rubble of late 60s Newark. Next, presumably, we’ll get an adaptation of I Married a Communist, Roth’s tale of a fiery Jewish radical who finds himself undone by his celebrity wife. I’m tipping Tyler Perry to direct.

Demi Moore in The Scarlet Letter. Photograph: Allstar/Cinetext/Buena Vista

Until then, McGregor’s film must take its place alongside a long list of cherished books which have been wantonly manhandled by philistine film-makers. Truman Capote’s bittersweet Breakfast at Tiffany’s was quickly made over as a simpering romcom. The Scarlet Letter became a convenient excuse to show Demi Moore in a bath. Gulliver’s Travels was customized to make room for Jack Black.Actually, I have a certain grudging affection for all of these follies. In their lumbering, roundabout fashion, they serve to reaffirm my love for the books they have tried and failed to pin down.

Also, some bad adaptations are more diverting than others. Back in 2013, Baz Luhrmann was accused of confusing F Scott Fitzgerald’s The Great Gatsby for a crass, rowdy party. And yes, fair enough, but is that really so terrible? Given the choice, I’d prefer my literary classics tackled by an eager vandal like Luhrmann than the Hollywood equivalent of a fawning, white-gloved footman, or all those solemn pallbearers who carried Harry Potter to the screen. Films are not literature and needn’t be treated as such. Stories need room to run and experiment and find their own route through a different medium. One of my all-time favorite adaptations, for instance, is Adaptation, in which Charlie Kaufman sets out to make a movie out of Susan Orlean’s The Orchid Thief and winds up casting himself as the hero and the author herself as a libidinous drug-user who contributes to an internet porn site. Orlean’s initial reaction, apparently, was not entirely positive.

Which brings us to another question. If you comprehensively screw up an adaptation, what actual harm does it do? It might be annoying for those who have to sit through it. It may even be irksome for some of those who have made it. But by and large these are small and self-contained disasters. The book itself isn’t hurt and the author is most likely sobbing all the way to the bank.

“People ask me, ‘Don’t you care what they’ve done to your book?’” said James M Cain, the author of Double Indemnity and The Postman Always Rings Twice. “I tell them, ‘They haven’t done anything to my book. It’s right there on the shelf.’” Or to put it another way, no film has the power to retroactively ruin a book. If the film gets it right, it confirms the book’s greatness. If the film gets it wrong, it proves that the book is unique. Either way, the book endures. Either way, its reputation improves. American Pastoral: the Movie looks likely to die a swift and quiet death at the box office. But American Pastoral’s fine. I can see it right now on my shelf.