Still from Blade Runner, based on Philip K. Dick's Do Androids Dream of Electric Sheep? Credit: denofgeek.com.

A few years ago, Iain Banks and I got into a pub conversation with another writer who wasn't a writer of science fiction. He didn't disdain SF, but wanted to know why it mattered so much to us.

We explained that SF was the language we used to engage with big questions: the dizzying vistas opened by science and technology; how societies work and how they change; what might yet be and what might have been. At its strongest, strangest moments SF gives its readers what some of them call ‘the sense of wonder’ – that distinctive, addictive kick of the sublime which comes from vividly imagining oneself in the presence of the immense: deep time, deep space, and natural or artificial objects of gigantic scale or fascinating complexity.

All this, and exploding spaceships on the cover! When we'd finished, our friend said: “It sounds like science fiction is your religion.” He stood up to get another round in, leaving us to admit between ourselves that in a sense he was right.

Like religion, SF gives us a symbolic relationship with a reality beyond, and yet intrinsic to and underlying, everyday life. That reality is the universe as we've come to understand it through science: vast, ancient, and indifferent; and inarguably there.

Where SF differs from religion is that the reality isn't apprehended by faith, but by everyday sense and reason.

What makes this reality intrinsic to everyday life is twofold: the changes in human self-knowledge that science has given us, and the changes brought about by the application of science to technology. Technological change is a major driver of social change – the most recent and obvious example being the ubiquity of communications and computer technology. Most people reading this are almost certainly doing so on the screen of a device that has become essential to their work and social life..

It might seem that I'm pushing at an open door here. No one worth arguing with could deny the profound effects of the scientific and industrial revolutions on society and human consciousness. Even those who regard these effects as regrettable, or the many who believe that the cosmos accessible to science isn't the whole of reality, would almost all agree that what science has discovered is real and important.

But in most art and culture, these realities are barely acknowledged. In literary fiction, unless the plot demands Australia, the Earth might as well be flat. A novel as much influenced by the findings of current psychology and neuroscience as some 20th-Century fiction was by psychoanalysis has yet to be written (though neuroscience has featured as subject matter in some novels: Ian McEwan’s Saturday and David Lodge’s Nice Work come to mind). This is partly a matter of focus and topic, of course, and partly down to the educational and life background of most literary novelists and the intellectual interests they have. And to be fair, the tradition of humane letters and the novel of character will always – at least for the foreseeable future – have its place.

But trying to understand and represent society today without understanding that it's constantly changing and that technology is changing even faster is to be always behind the curve. As SF author William Gibson has shown in some of his recent novels, an effective way to write about the present is to write SF set in the very near future – or even in the immediate past.

SF readers know in their bones that there’s a big universe out there, and that science increasingly changes everyday life: two truths that are as overwhelming as they're unacknowledged. They also learn an attitude towards them. In most SF, problems are there to be solved. If they can't be solved, it's unfortunate, but it isn't fate. The unique capacity of the human being to act rationally on the world is celebrated in SF, and almost nowhere else.

These three features – a lively interest in the world beyond humanity, fascination with how knowledge of that world changes humanity, and confidence in human ability to understand and change the world – are what mark out SF. It isn't the content: there are plenty of stories set in the future, or involving aliens or new inventions, that aren't SF. We read them as dystopias, or parables, or technothrillers, or satires, and we're right.

In this sense, writers such as Margaret Atwood and Michel Faber aren't writing SF, even when they're writing about future theocracies or missionaries on extrasolar planets. Their novels have great depth and resonance, but not that stubborn didactic streak of SF, the obsession with how things other than human beings work. The true literary novelist finds people and what they get up to the most fascinating topic imaginable. The SF writer – painful as it is to admit – doesn't.

This isn't necessarily down to authors' personal traits. Aldous Huxley was more cultured and balanced than George Orwell, but Brave New World is science-fictional in a way that Nineteen Eighty-Four isn't. Huxley's world-building is sound. His prenatal manipulation, hypno-education, soma and so on would (on the basis of the science of his day) plausibly work. They hang together and make sense. Orwell's world-building is a bit like one of his Victory cigarettes: when you hold it up the contents fall out. It's all very well the current ally becoming the enemy overnight, but how does 'Oceania has always been at war with Eurasia' go down on the front lines? On the military airfields? In the offices of the General Staff? Why don't the vast colonial populations over which the three superpowers fight ever come up with a resistance? Implications are not thought through. Orwell's novel works as Swiftian satire, not as SF.

I find it frustrating that so few people involved in politics, and particularly on the left, read SF. When they do value SF, it's usually instrumentally: as a vehicle for utopian hope, dystopian warning, or science communication. The SF mind-set and mental tool-kit can do far more. The most fundamental lesson of SF is that the future will be different. This sounds banal, but it's remarkable how few take the point seriously. And when people who aren’t familiar with SF do imagine the future, the default scenario is almost always dystopian and catastrophic – as I’ve invariably found in scenario-building exercises for various projects, whether literary or social and political.

It staggers me that people can discuss, say, the challenges an aging population poses to healthcare without thinking about what else is likely to change between now and, say, 2040. We can't foresee the medical technology and drugs of that time, but we can be sure they'll have changed the game radically.

It's reasonable to expect that by 2040 a person in their 60s can look forward to decades of healthy life. But if you point that out to the typical person of the left, they'll nod wisely and say, “Ah, but that'll be only for the rich.”

Every modern advance in consumer technology: video recorders, CDs, satellite television, home computers, mobile phones, the Internet, smart phones, has climbed a predictable ladder of dismissal from the left. They go from plaything of the rich, through passing fad, through latest tool of oppression, to ... necessity of life that it's a scandal people on benefits can't afford. Older comrades assure me that the same happened with television, radio, the motor car...

If my experience of decades of conversations in person and online is anything to go by, this isn't a mistake habitual SF readers (and viewers) make: they know things change in many complex ways, and that manufactured stuff gets cheaper. In SF novels such as Gibson’s Neuromancer, and films such as Blade Runner, they see people on low incomes owning and using technology that a billionaire couldn’t afford today.

They also know that making more stuff cheaper can change the environment. SF writers and readers are open to a lot of ideas, some eccentric or toxic, but climate change denial is seldom among them. When you've imagined terraforming – changing the atmosphere and biosphere of an entire planet – the idea that human activity and industry can change our own atmosphere in potentially catastrophic ways is hardly alien. And you're already used to imagining catastrophes, and yourself and people you care about living to see them. You’re also used to imagining ways in which catastrophes can be mitigated or averted by intelligent forward planning, or even by accidents of technological change – which can’t be counted on, but can’t be discounted either.

We live in a golden age of science popularization -- and a dark age of public misunderstanding and suspicion of science. Science popularization and education can do much, but can't make us feel that what we're learning is real, and that we should take it personally. For that we need imaginative engagement.

What SF, even badly written or scientifically outdated SF, can contribute is that sense of personal connection, rooted in the sense of wonder.