Claire Dederer is a journalist from Seattle and the author of two memoirs, the most well known of which is Poser: My Life in Twenty-Three Yoga Poses. In 2017, she wrote a piece for the Paris Review entitled What Do We Do With the Art of Monstrous Men? in which she described the experience of rewatching the early films of Woody Allen (Annie Hall, Manhattan) in the context of the allegations of abuse made against him by his adopted daughter, Dylan. The #MeToo movement was then just beginning and this piece, according to her publisher, went viral. Six years on, and it has now also been incorporated into Dederer’s new book, Monsters: A Fan’s Dilemma, where it loiters alongside her thoughts on several other bad (or badly behaved) men who have made good art, among them Picasso, Roman Polanski and Richard Wagner.

This is a good subject, and a perennial one – it long predates cancel culture: anyone who read English at university in the 80s, when literary theory was enjoying its crazy, ascetic heyday, will have spent at least some of the past 30 years arguing about the degree to which life and art can or should be separated – and Dederer certainly talks a big game as she begins. Her approach will be nuanced, she suggests, paraphrasing the poet William Empson, who believed all of us must somehow exist between contradictions that can’t be solved by analysis. She will, she suggests, inevitably end up saying things some readers may find uncomfortable. For instance: having spent many hours in her cosy, book-lined, “humanist” house watching the films of Polanski, who in 1977 drugged and raped a 13-year-old girl, Dederer’s verdict on his work is (rightly, I think) unchanged: Chinatown is still a masterpiece.

But oh, how quickly her courage fails her! Though she never fully articulates it, the reader senses her particular anxiety: an apprehension that has to do with what people – young people, woke people, the kind of people who might in future be in a position to commission her (or not) – are going to think of her now. She wants so badly to be liked. How otherwise to explain her constant equivocations? Her craven assertion that she may carry “the stain of being a certain kind of white middle-class feminist”?

And isn’t this why she soon sets about throwing JK Rowling under the bus, on the grounds of her disagreement with gender identity theory (though Dederer gets woefully muddled here, writing that Rowling is “aligned” with “the gender identity movement”, which is in fact the polar opposite of her position)? Harry Potter fans are right to be angry, she writes, for Rowling has excluded them from their cherished childhood “dreamscape”. If Dederer is aware that this condemnation sits rather awkwardly, to put it mildly, with what she says elsewhere – like Polanski’s films, Rowling’s novels are still the same books they were a decade ago – she isn’t letting on.

Dederer has seemingly spent years working on Monsters and yet it is so thin, so ill-researched and, frequently, so crude. Part of her problem is that she struggles to convey the beauty and greatness of much of the art she describes, which makes it all the easier for the reader who disapproves of its makers simply to refuse to engage with it. She’s OK on the movies, and her account of Nabokov’s Lolita is fine (though why Nabokov is here at all, I’m not sure: whatever his most infamous narrator does, the writer committed no crimes against children or anyone else). But once she gets to Picasso and Wagner, she’s in trouble. Picasso, she says, sounding like an overgrown teenager, makes her feel (a favourite word, this) “urpy”. He was such “a rat”. What she knows of Wagner, included in the book on the grounds of his strident antisemitism, seems to be based entirely on a documentary about the composer made by Stephen Fry and Simon Callow’s biography.

The feeling grows that she doesn’t know what she’s doing. Thoughts and ideas come and go, explored at various speeds and in various gears, like cars on a busy motorway. You want to flag one down, but they never quite pull over. Why does she suddenly alight on the novelist James Salter? Is his last novel really a “report” from the “vilest backwaters of male desire”? (My italics.) When she moves on to female artists, including Joni Mitchell and Doris Lessing, things get even worse. Dederer isn’t wrong to suggest our culture will always rule against the woman who is insufficiently maternal. But she seems to struggle not to do the same herself, telling us – this is so grim and reductive – that when she thinks of them, she thinks of lost and abandoned children. (Mitchell gave up a baby for adoption; Lessing left two of her children in Southern Rhodesia when she fled to London in the late 40s.)

In her hands, vexed territory is oddly flattened out, its provocations mere mole hills on the way to nowhere. But in truth, I was more often baffled than bored. Virginia Woolf’s antisemitism (Dederer proudly tells a Jewish friend that she has “rumbled” this) hasn’t been forgotten; Allen Ginsberg isn’t better known than Philip Larkin (or not in Britain, anyway); JK Rowling doesn’t live in England. Monsters is populated with auteurs, with people whose instincts are singular and extreme, but its author’s real predilection seems to be for generalisation. An unwarranted detour into the world of scientists has her trotting out all the cliches about their eccentricity, the tattered garments and rope belts she believes they use to burnish their “genius”. Who can tell Picasso’s abused women apart? Not her, she tells us. They’re a “fleshy pig-pile” and she – well done, sister! – can never remember which is which.

I put Monsters down with the feeling I’d been complicit in something – though precisely what, I cannot quite say. I guess, in the end, this is publishing having its cake and eating it. Look! the book says, a little smugly, we’re not closing down debate. Here are a thousand questions, and we’ll get back to you some other time (like, never) about the answers.

• Monsters: A Fan’s Dilemma by Claire Dederer is published by Sceptre (£20). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply

• This article was amended on 10 May 2023. Doris Lessing left two of her children in Southern Rhodesia (now Zimbabwe), not South Africa as an earlier version said.