Let's think about reading – about what it's like to read. And after we've thought about reading for a while, let's consider writing – and what it means to write. There are many ways of reading: we scan, we dip, we skip and we speed through texts we know to be intrinsically dull, searching out the nuggets of information we desire as a bent-backed prospector pans for gold. In contradistinction: we are lost, abandoned, absorbed – tossed from wave to wave of language as we relapse into the wordsea. All serious readers of serious literature have had this experience: time, space, and all the workaday contingencies of their identity – sex, age, class, heritage – are forgotten; the mind cleaves to the page, matching it point-for-point; the mind is the text, and in the act of reading it is you who are revealed to the impersonal writer, quite as much as her imaginings and inventions are rendered unto you. In the course of my literary career I've read various accounts of the reading process – ones that analyse it phenomenologically, neurologically and psychologically; ones that site it in a given social or cultural context – but none has captured the peculiar quiddity of reading as I experience it. In particular, no forensic or analytic account of reading can do justice to the strange interplay between levels of reality we apprehend when we read deeply. We don't picture a woman in a red dress when we decipher the marks that mean "she wore a red dress" – and, by extension, we do not hold within our mind's eye the floor plan of Mansfield Park or the street map of Dublin when we read the novels of Jane Austen and James Joyce, respectively.

Yet, somehow, we know these places. The clearest possible example of the strange telepathy implicit in deep reading that I've arrived at is one that every reader I've ever explained it to understands intuitively: when we read a description of a place we get whether or not the writer truly knows that place, even if we have no familiarity with it ourselves. In a world made up of printed codices, and all the worlds they in turn describe, the reader strives to see in them, see through them, and to discern the connections between them. When she experiences difficulties with a text – the meaning is obscure, the syntax confused and the allusions unknown to her – she either struggles until she comprehends, or, if she is utterly stumped, she consults another book. This way of going about the business of reading is so well-established and so completely inhabited by those of us who have grown up with what Marshall McLuhan termed "Gutenberg minds", that we barely give it any thought. By extension, we are scarcely able to apprehend what it might be like to not have to read deeply at all; if, indeed, it were possible to gain all the required information necessary to understand a passage simply by skimming it, and, where an obscurity is highlighted, clicking on this to follow a hypertext link. There has been a lot of research on digital as against analogue reading, and the results are decidedly mixed. On the one hand, sceptics and Cassandras point to the fracturing of attention and the attenuation of memory they see lying behind the screen; they also point out that the kind of reading I've described above becomes impossible once text is displayed on an internet-enabled device – unless, that is, readers are self-disciplined enough to not use the web.

Web-boosters and info-geeks take quite another tack, finding in digital reading new forms of stimulus and engagement. I haven't the space here to weigh up the competing claims, but one thing is absolutely clear: reading on screen is fundamentally different from reading on paper, and just as solitary, silent, focused reading is a function of the physical codex, so the digital text will bring with it new forms of reading, learning, memory and even consciousness.

I think this so self-evident as to scarcely require elucidation; the unwillingness of the literary community – in its broadest sense – to accept the inevitability of this transformation can only be ascribed to their being blinkered by the boards of their codices. The majority of the text currently read in the technologically advanced world is already digitised – and most of that text is accessed via internet-enabled devices. All the valorisation of the printed word – its fusty scent, its silk, its heft – is a rearguard action: the book is already in desperate, riffling retreat. The relationship between words and revenue has become a debatable one – we can wax all we like about the importance of the traditional gatekeepers and the perspicacity of editors and critics in separating out the literary wheat from the pulpy chaff, but the fact is that these professions depend on the physical book as a commodity. It is the sad bleat of the book world that we'll be sorry once they're gone – and with them all the bookshops, literary reviews, libraries and publishing houses that supported their endeavours – but it was their mistake to assume their acumen to be inelastic. I mean by this, that a certain kind of expertise was understood to have a value to its consumers that was both constant and capable of being monetised at a fixed rate. The web has grabbed hold of this inelasticity and stretched it until it has snapped back in the myopic faces of the literati.

Back when I began publishing novels, not only did the reviews in the quality press mean something – in terms of sales, yes, but also as a genuine assay of literary worth – but as a writer, you knew that there was a community of readers who paid attention to them. No longer. The rise of reading groups and online readers' reviews represents the concomitant phenomenon to the political parties' use of focus groups to formulate policy: literary worth is accorded to what the generality want; under such terms of endearment, what is loved is what has always been loved, and the black swan of innovation flies unseen and unheralded.

Follow the money is always the maxim when it comes to understanding the complex processes that it mediates. Since the abolition of the Net Book Agreement in the 1980s, all the money in publishing has been funnelled into pipes that have a wider and a shorter bore; nowadays one big, thick pipeline carrying half the revenue from British retail book sales disappears deep into Jeff Bezos's pockets. The NBA itself was part of a government subsidy system that included preferential tax rates for newsprint, public libraries and even the grants awarded university students from poorer backgrounds – all of it was based on the assumption that the cultural value of reading and writing wasn't reducible to its economic worth. Nowadays all we can say about the production and consumption of the written word is that it is subject to exactly the same iron laws of supply and demand as every other widget or pixel.

Under such parlous circumstances, with all cultural value being colossally devalued in order to achieve parity with the pound, the traditional gatekeepers are precisely who we look to for the preservation of the logos. In the past, the church was a repository of scholarship for its own sake – but, nowadays, we are a resolutely secular society, unless, that is, you subscribe to fundamentalist revealed religion. The academy is now a profit centre all its own, with academics publishing online in order to secure professional advancement, rather than because their scholarship is meaningful or valuable; and university administrators encouraging the development of courses of "study" – such as creative writing – that are no such thing, but rather steady revenue streams for institutions dependent on fee income.

My personal motto is "I just want to be misunderstood", and I've been gratified by just how misunderstood my sallies into the vexed terrain of the epochal technological transformation that is being enacted right before our line-scanning eyes have been. I am not in the least bit pessimistic about these developments – I don't think the telephone, the radio, film or television made our culture in any sense more "stupid" or "ignorant". I believe that our society – and others – will both preserve its storehouse of knowledge and use digital media to develop new forms of understanding, including what it means to be literate. The losers in all of this will be traditional cultural forms that were dependent on the technology of the codex: the extension of the human mind into the virtual inscape is already under way; people no longer depend on their own, personal and canonical memory to analyse and validate new information – they have outsourced such mental operations to algorithms owned by Sergey Brin et al. As to whether such dependence on what is, effectively, a monetised intellectual prosthesis will impact negatively on our culture, the answer has to be an emphatic "yes" – unless, that is, the new web-dependent generations seek their own liberation from the shackles of late capitalism, just as their foremothers and fathers won concessions from those who owned the mechanical means of production.

But, I hear you cavil, this is the realm of politics rather than culture. Really? And since when have the two been remotely separable? The argument about whether the web is value-neutral is simply addressed: were this resource to be truly incapable of being owned, then yes, the tweeting Arab Spring might have culminated in a warm summer of blooming democracy; but the fact is that the commanding heights of the web are already occupied by those who view it as a cash cow grazing in a global field.

None of this, however, counts for anything when it comes to the future of our literary culture – its fate is already sealed, and there is no going back. I began this provocation by describing what I think of deep reading – the kind of reading that serious books demand, and I promised that I would also discuss writing, the kind of writing that's intended to be read deeply. But really, there's no point in this, because such writing depends for its existence on deep readers, and in the near future such deep readers will be in very short supply.

• This essay is an edited version of a commissioned piece from Writers' Centre Norwich and Cheltenham Literature Festival as part of today's National Conversation event. For more information, go to http://www.nationalcentreforwriting.org.uk