If they weren’t already here, we’d have to invent them: public spaces, crammed with books, computers and information points, where events and meetings regularly take place, and children in particular get an early taste of the world beyond their own immediate experience.

The author Robert Macfarlane says that public libraries are nothing less than “magic portals into learning and dreaming”. Virginia Woolf once said they were “full of sunk treasure”. When it comes to libraries’ civic importance, their modern supporters tend to use terms such as “community hub”, but on that score, I would rather turn to 24 elegant words uttered by the American philanthropist Andrew Carnegie: “A library outranks any other one thing a community can do to benefit its people. It is a never failing spring in the desert.”

Slightly less romantically, in an age in which access to the internet is a necessity, libraries represent pretty much the only public place that people without a computer or smartphone can get online. In among its endless demands and diktats, the new system of universal credit makes this compulsory – as evidenced by a woman I recently met in Newcastle, who said that every time she received a text message from the jobcentre, she had to gather together her kids and sprint to the local library, to find out what’s now required of her, for fear of having her benefits stopped.

Libraries are also one of the most solid collective bulwarks against the modern scourge of loneliness: places that offer shared experience and a chance to linger among company, without having to spend any money.

But does anyone in government care? Since 2010, at least 478 libraries have closed in England, Wales and Scotland. Over the same period, the number of books held by surviving libraries has dropped by 14m, while librarian numbers have been cut by around 8,000. Statistics released this week by the Chartered Institute of Public Finance and Accountancy show that over the past five years, loans of books have dropped by a quarter, and that spending on libraries by councils fell by £66m in 2016-17 alone.

The results are heartbreaking: according to research by Tim Coates, the former managing director of Waterstones, book loans to children in Birmingham have fallen by 32% since 2011. In Newcastle the figure is 35%; in Sheffield 56%. The numbers are mind-boggling, and it’s obvious what they denote: reading being snatched out of young lives, with a blithe cruelty that ought to make ministers ashamed.

While too much of the national media now behaves as if austerity was something that began and ended with the David Cameron years, it goes on apace. Across the country, as money from Whitehall continues to be cut and council leaders fret about how local authorities are to avoid financial ruin, places still face seemingly endless economies. In Norfolk, the ruling Tory council is eyeing cuts of around £100m over the next four years. Bradford faces cuts of £30m between now and 2020; in Leicestershire, £54m will have to go by 2022. In the reports of these ongoing disasters, one kind of sentence recurs time and again. It goes something like this: “Services including street cleaning, libraries, and museums and galleries are set to be among the hardest hit.”

And so it proves. Around half of people in the UK are now reckoned to be at least occasional library users; among 25- to 34-year-olds in England, the use of libraries has actually risen since 2011. In English cities, the busiest libraries continue to rack up huge annual visitor numbers, in excess of a million each. But instead of being modernised and developed, far too many libraries are still either cutting back their hours, or closing. In Northamptonshire, the council is considering shutting as many as 28 of the county’s 36. In Bury, near Manchester, 10 of 14 are about to close. Closures are also looming in Cheshire, East Sussex, Anglesey, Shropshire and more.

In Edinburgh, 2018 will see a pilot in which libraries are run without any staff (“CCTV cameras, emergency telephones, loudspeakers and alarms will ensure security when libraries are unstaffed,” apparently). In other places, drawing on the dying embers of the “big society”, there is the usual talk about keeping services running by handing things over to volunteers – which is obviously much better than nothing, but threatens to turn a properly funded public resource into a Cinderella service, often cut loose from an area’s official library system. Finding sufficient volunteers in disadvantaged areas is often a big problem. Suddenly, replenishing book stocks becomes a matter of appeals to the public, and such matters as building maintenance and cleaning are the focus of ongoing worry.

The danger, clearly, is that the aroma of the jumble sale soon arrives, and the stupid idea that libraries are some kind of outmoded relic becomes a self-fulfilling prophecy – something highlighted by an early warning contained in a letter written to the Swindon Advertiser back in 2010. The subject was a library handed over to the so-called third sector, which had decayed at speed: “It has no real library staff, is now shut on Saturdays and is no longer available for the local schools to use, because there’s no room available since the charity shop moved in. It is now, in fact, a charity shop with some stacks of books as a sort of afterthought.” Somewhere in those words is a neat diagnosis of the modern British condition.

When it comes to people trying to manage their benefit payments, the sudden loss of libraries only adds to the sense of a system run on a mixture of chaotic ineptitude and an entirely deliberate Kafkaesque cruelty. And in the context of the importance of learning, savaging library provision highlights the old con trick whereby Conservative politicians talk up the wonders of social mobility and self-improvement, while attacking the very institutions that give those ideas any meaning.

Dozens of Tory politicians regularly shine light on that hypocrisy – such as the high-profile Eurosceptic Bernard Jenkin, currently one of the more verbose occupants of the Conservative benches, and a man who embodies all the awful delusions that still afflict his party. On a recent edition of Question Time broadcast from Swansea, he took exception to an audience member’s mention of the class system. “I wish we’d just stop talking about class,” he said. “Class isn’t important. It doesn’t matter where you’ve come from. We should provide the country with opportunities.”

These are the same people who are not only starving state schools of money, but who have now spent seven long years attacking a public service that is a byword for the education and opportunity they bang on about. Somewhere in the deepest recesses of their souls, they must know: you cannot talk about such things while depriving people of the chance to read. Other than as an example of howling cant, it makes no sense.

• John Harris is a Guardian columnist