Books have always been rude and tendentious and apt to make people mad. Deploy a sense of perspective and our own times, in which Roald Dahl is rewritten and Charles Dickens is excommunicated, don’t seem special at all. In 1925, to take just one example, rumours reached the authorities in Cambridge that a young university lecturer called FR Leavis was intending to discuss Ulysses by James Joyce with his students – a novel that had fallen foul of the 1857 Obscene Publications Act. And sure enough, the police soon arrived in college to examine this wunderkind’s bookshelves, a scene that’s really quite funny if you picture it (all those tooled leather volumes by Jane Austen and Henry James). But they weren’t laughing, and nor was the home secretary, who now threatened the university with prosecution. Leavis’s little seminar, then, did not go ahead – and nor did any others, anywhere, or not for a long time. When John Sutherland, who relates this story in his new book, was a teenager in the 1950s, his local library still kept its copy of Ulysses, complete with five pages razored out of it, carefully hidden from public view.

But still, it does feel to me, and to many others, that we are once again growing less liberal, and it’s into this territory that Sutherland now steps with Triggered Literature: Cancellation, Stealth Censorship and Cultural Warfare. In some ways, of course, this is an obvious place for him to loiter awhile. The so-called trigger warnings lately issued by some institutions – Mansfield Park will upset you! Macbeth will make you feel ill! – are bound to be of interest to a man like him, after all. In the years after the Chatterley trial in 1960, he was a groovy young fellow, taking full advantage of all the new freedoms; as he rose up the academic ranks, it was his job to oversee the curriculum (he is emeritus Lord Northcliffe professor of modern English literature at University College London); the novels of his beloved William Makepeace Thackeray are now deemed to be horribly racist.

But in other ways, it’s clearly uncomfortable for him. How nervous he is of tackling the subject head-on! How fearful of sounding like a has-been (or, worse still, a bit too right wing). If it’s outraged blasts from the Daily Mail you’re after, you’ll find plenty of them here. Sutherland himself, however, is seemingly determined not to be outraged by anything – even, or perhaps especially, when outrage really should be the order of the day.

Having traced the word “triggering” back to the US where, in 2014, the New York Times first reported that students at scores of institutions were demanding warnings on such canonical texts as The Great Gatsby by F Scott Fitzgerald and Mrs Dalloway by Virginia Woolf, he provides a tour d’horizon of many of the incidents since in which books have been deemed potentially harmful to the reader’s state of mind. He also tells us about sensitivity readers, and the various databases that aim to help readers feel better “prepared” and more “safe” ahead of reading a book (to amuse myself, I looked up Agatha Christie’s The Mysterious Affair at Styles on one of these; among the triggers listed were cheating, murder and character death – and, no, I’m not making this up). But, alas, his own terminology is confusing. Throughout, he uses “triggered” not to refer to those people who find themselves disturbed by Enid Blyton or John Cleland, but to denote those books that now come with trigger warnings. By his telling, August Strindberg is “triggered”, and Colson Whitehead. So, too, is Oliver Twist. It’s bizarre and on the page it makes no sense at all.

You can’t say he dives deep; mostly, this book only snorkels along, just beneath the surface. He relies almost entirely on the cuttings library: no one is interviewed; no headline is debunked. Wry rather than polemical, he only ever passes judgment on what is effectively censorship when (in my view) it feels safe to do so; when other people are unlikely to disagree or get upset. The trigger warnings issued by Glasgow University to theology students who signed up for a lecture called Jesus and Cinema, which made mention of Mel Gibson’s 2004 film The Passion of the Christ, were, in his opinion, “wholly justified”. But about Maia Kobabe’s controversial 2019 young adult graphic novel Gender Queer, he’s unwilling to come to any conclusions. His long account of the upsetting views of Charles Dickens isn’t utilised to encourage the writer’s cancellation. But what he has to say about Dickens’s talent as a writer isn’t intended to encourage us to read him either. It’s all passionless at best, and weedy at worst.

It’s good to know that when Sutherland read DH Lawrence’s Lady Chatterley’s Lover by the Seine at the age of 16, he did so in “a condition of total erectionlessness”. But what I really wondered as I read his book was: do trigger warnings (with which I disagree on principle) even work? Although he is bizarrely sceptical of the one study he cites – the National Library of Medicine in the US found that students with “relevant traumas” do not avoid triggering material even after receiving a warning about it, that its effect on them subsequently appears to be brief, and those with PTSD reported no exacerbation of their symptoms – I was pleased to read of it. While those in the sample might not much have liked Toni Morrison’s The Bluest Eye, it did them no harm – and this way, surely, common sense lies.

• Triggered Literature: Cancellation, Stealth Censorship and Cultural Warfare by John Sutherland is published by Biteback (£18.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply