There’s an episode of Friends – The One With The Free Porn – in which Chandler and Joey discover they have tuned into a porn channel. And it’s free. They leave the TV on, afraid switching off will mean no more pornography. By the end of the episode, Chandler is seeing the world through porn-tinted spectacles. “I was just at the bank,” he complains, “and the teller didn’t ask me to go do it with her in the vault.” Joey, bewildered, reports a similar reaction from the pizza-delivery girl. “You know what,” decides Chandler, “we have to turn off the porn.”

As a society, however, we are further from turning off porn than we have ever been. Pornography is everywhere – it masquerades as “gentlemen’s entertainment” in the form of clubs such as Spearmint Rhino, it infiltrates advertising and it will soon be available in our back pockets, thanks to a deal by adult entertainment giant Private Media Group to beam porn to UK mobile phones.

In its hardcore form, pornography is now accessed in the UK by an estimated 33% of all internet users. Since the British Board of Film Classification relaxed its guidelines in 2000, hardcore video pornography now makes up between 13% and 17% of censors’ viewing, compared with just 1% three years ago, a rate of growth that is being cited as a causal factor in the recent bankruptcy of Penthouse, at one time the very apotheosis of porno chic but in recent years little more risqué than Loaded. In the US, with the pornography industry bringing in up to $15bn (£8.9bn) annually, people spend more on porn every year than they do on movie tickets and all the performing arts combined. Each year, in Los Angeles alone, more than 10,000 hardcore pornographic films are made, against an annual Hollywood average of just 400 movies.

Pornography is not only a bigger business than ever before, it is also more acceptable, more fashionable, and more of a statement of cool. From pieces “in praise of porn” in the normally sober Prospect magazine to such programmes as Pornography: The Musical on Channel 4 last month, to Victoria Coren and Charlie Skelton’s book, published last year, about making a porn film, to the news that Val Kilmer is to play the part of pornography actor John Holmes in a new mainstream movie, there is a widespread sense that anyone who suggests pornography might have any kind of adverse effect is laughably out of touch. Coren and Skelton, former Erotic Review film critics, focus on their flip comic narrative, scarcely troubling themselves with any deeper issues. “In all our years of watching porn,” they write, in a rare moment of analysis that doesn’t get developed any further, “we have never properly resolved what we think about how, why and whether it is degrading to women. We suspect that it might be. We suspect that pornography might be degrading to everybody.”

With pornography, it seems as if the sheer scale of the phenomenon has, in time-honoured capitalist fashion, conferred its own respectability; as a result, serious analysis is hard to come by. Only occasionally, amid porn-disguised-as-documentary that distinguishes much of Channel 5’s late-night output, is there broadcasting that gives any kind of insight. Channel 4’s documentary Hardcore, shown two years ago, told the story of Felicity, a single mother from Essex who travelled to Los Angeles hoping to make a career in pornography. Arriving excited, and clear about what she would not do – anal sex, double-vaginal penetration – she ended up being coerced into playing a submissive role and agreeing to anal sex. Felicity – the vicissitudes of whose own troubled relationship with her father was mirrored by the cruelty of the men with whom she ended up working – eventually escaped back to the UK.

Hardcore offered a rare, unadorned look at the inside of the industry, as did Pornography: The Musical, albeit in a more surreal form, with actors interrupting sex to break into song. Yet what about the millions who consume pornography, the men – for they are, despite pornographers’ claims about growing numbers of female fans, mostly men – who habitually use it? How are they affected? Is pornography, as most these days claim, a harmless masturbatory diversion? That episode of Friends, albeit with tongue in cheek, suggested a heavy diet of porn might encourage men inappropriately to expect sex. Is that true? And what about more profound effects? How does it affect relationships? Is it addictive? Does it encourage rape, paedophilia, sexual murder? Surely tough questions need to be asked.

First, though, some definitions. According to the Shorter Oxford Dictionary, the word “pornography” dates to 1864, when it described “the life, manners, etc of prostitutes or their patrons”. More recently, it has come to signify material, in the words of Chambers, “intended to arouse sexual excitement”. Its most common themes, however, are power and submission. By contrast, “erotica”, which is pretty hard to find now, carries additional connotations of “amorousness” and is far less concerned with control and domination. No, it is pornography plain and simple, from teen magazines such as Front to venerable “wrist mags” such as Playboy to the almost daily bombardment of teaser pornographic emails, that confronts all of us on a ceaseless basis.

The received wisdom, pushed hard by such mass-market magazines as Loaded and FHM, is that men derive a pretty uncomplicated enjoyment from pornography. That, certainly, is the argument put forward by such proponents as David Baddiel, AA Gill, who has directed his own pornographic film, and the musician Moby, who once said in an interview, “I like pornography – who doesn’t? I don’t really trust men who claim to not be interested in porn. We’re biologically programmed to respond to the sight of people having sex.” Danny Plunkett then features editor of Loaded, takes an equally relaxed view: “We know that a lot of people enjoy it and take it with a pinch of salt. We certainly don’t view it as dangerous.”

But is it as simple as this? One of my best friends is a man for whom pornography has apparently never held even the slimmest interest. Moby may choose to distrust him, but his sex life otherwise has always seemed to me perfectly robust. He is, however, so much in the minority as to seem almost an oddity.

For most men, at some point in their lives, pornography has held a strong appeal and, before any examination of its effects, this fact has to be addressed. Like many men, I first saw pornography during puberty. At boarding school, dog-eared copies of Mayfair and Knave were stowed behind toilet cisterns; this borrow-and-return library system was considered absolutely normal, seldom commented upon and either never discovered by the masters or tacitly permitted. Long before my first sexual relationship, porn was my sex education.

No doubt (though we’d never have admitted it then) my friends and I were driven to use porn through loneliness: being away from home, we longed for love, closeness, and unquestioning acceptance. The women over whom we masturbated – the surrogate mothers, if you like – seemed to be offering this but, of course, they were never going to provide it. The untruths it taught me on top of this disappointment – that women are always available, that sex is about what a man can do to a woman – I am only now, more than two decades on, finally succeeding in unlearning.

From men everywhere come similar stories. Nick Samuels, 46, an electrical contractor from Epping – now, with a wife and four children, the very image of respectable fatherhood – says he first discovered the power of pornographic images at the age of 16, when he found a copy of Mayfair in his father’s garage. “I can even remember the picture. There was a woman walking topless past a building site and the builders were ogling her from the scaffolding. It was pretty soft stuff, but it heightened my senses and kicked off my interest in pornography. Before long, I was reading Whitehouse and then, through a friend at my squash club, I was introduced to hardcore videos.”

Si Jones, a 39-year-old north London vicar who regularly counsels men trying to “come off” pornography, admits that, for him, too, it was his introduction to sex. “As a teenager, I watched porn films with my friends at the weekend. It was just what you did. It was cool, naughty and everyone was doing it.” Set against today’s habit of solitary internet masturbation, Jones’s collegiate introduction to porn seems peculiarly sociable. Today, boys no longer clandestinely circulate magazines after school; nor do they need to rummage through their fathers’ cupboards in search of titillating material. Access to internet pornography has never been easier, its users never younger, and the heaviest demand, according to research published in the New York Times, is for ” ‘deviant’ material including paedophilia, bondage, sadomasochism and sex acts with various animals”.

At its most basic level, pornography answers natural human curiosity. Adolescent boys want to know what sex is about, and porn certainly demonstrates the mechanics. David Morgan, the consultant clinical psychologist and psychoanalyst at the Portman Clinic in London, which specialises in problems relating to sexuality and violence, describes this phase as “transitional, like a rehearsal for the real thing. The problem with pornography begins when, instead of being a temporary stop on the way to full sexual relations, it becomes a full-time place of residence.” Morgan’s experience of counselling men addicted to porn has convinced him that “the more time you spend in this fantasy world, the more difficult it becomes to make the transition to reality. Just like drugs, pornography provides a quick fix, a masturbatory universe people can get stuck in. This can result in their not being able to involve anyone else.”

For most men, the way pornography objectifies sex strikes a visceral emotional chord. Psychotherapists Michael Thompson and Dan Kindlon, in their book Raising Cain: Protecting The Emotional Life Of Boys, suggest that objectification, for boys, starts early. “By adolescence, a boy wakes up most mornings with an erection. This can happen whether he is in a good or bad mood, whether it is a school day or a weekend … Boys enjoy their own physical gadgetry. But the feeling isn’t always, ‘Look what I can do!’ The feeling is often, ‘Look what it can do!’ – again, a reflection of the way a boy views his instrument of sexuality as just that: an object. What people might not realise when they justly criticise men for objectifying sex – viewing sex as something you do, rather than part of a relationship – is that the first experience of objectification of sexuality in a boy’s life comes from his experience of his own body, having this penis that makes its own demands.”

But the roots go back further still. Research has shown that boy babies are treated more harshly than their female counterparts and, as they grow up, boys are taught that success is achieved through competition. In order to deal with this harsh masculine world, boys can learn not to trust their own feelings and not to express their emotions. They become suspicious of other men, with whom they’re in a competition, after all, and as a result, they often feel lonely and isolated.

Yet men, as much as women, hunger for intimacy. For many males, locked into a life in which self-esteem has grown intrinsically entwined with performance, sex assumes an almost unsustainable freight of demands and needs. Not only does the act itself become almost the only means through which many men can feel intimate and close, but it is also the way in which they find validation. And sex itself, of course, cannot possibly satisfy such demands.

It is into this troubled scenario that porn finds such easy access. For in pornography, unlike in real life, there is no criticism, real or imagined, of male performance. Women are always, in the words of the average internet site, “hot and ready”, eager to please. In real life, by contrast, men find women are anything but: they have higher job status, they demand that they be sexually satisfied, and they are increasingly opting to combine career and motherhood.

Men, say psychologists, also feel threatened by the “emotional power” they perceive women wielding over them. Unable to feel alive except when in relationships with women, they are at the same time painfully aware that their only salvation from isolation comes in being sexually acceptable to women. This sense of neediness can provoke intense anger that, all too often, finds expression in porn. Unlike real life, the pornographic world is a place in which men find their authority unchallenged and in which women are their willing, even grateful servants. “The illusion is created,” as one male writer on pornography puts it, “that women are really in their rightful place and that there is, after all, no real and serious challenge to male authority.” Seen in this light, the patently ridiculous pornography scenario of the pretty female flat-hunter (or hitch-hiker, a driver with a broken-down car, or any number of similar such vulnerable roles) who is happy to let herself be gang-banged by a group of overweight, hairy-shouldered couch potatoes makes perfect psychological sense.

The porn industry, of course, dismisses such talk, yet occasionally comes a glimmer of authenticity. Bill Margold, one of the industry’s longest-serving film performers, was interviewed in 1991 by psychoanalyst Robert Stoller for his book Porn: Myths For The Twentieth Century. Margold made no attempt to gloss over the realities. “My whole reason for being in this industry is to satisfy the desire of the men in the world who basically don’t care much for women and want to see the men in my industry getting even with the women they couldn’t have when they were growing up. So we come on a woman’s face or brutalise her sexually: we’re getting even for lost dreams.”

As well as “eroticising male supremacy”, in the words of anti-porn campaigner John Stoltenberg, pornography also attempts to assuage other male fears, in particular, that of erection failure. According to psychoanalytical thinking, pornography answers men’s fetishistic need for visual proof of phallic potency. Lynne Segal, professor of psychology and gender studies at Birkbeck College, University of London, writes: “Men’s specific fears of impotence, feeding off infantile castration anxiety, generate hostility towards women. Through pornography, real women can be avoided, male anxiety soothed and delusions of phallic prowess indulged, by intimations of the rock-hard, larger-than-life male organ.”

Pornography, in other words, is a lie. It peddles falsehoods about men, women and human relationships. In the name of titillation, it seduces vulnerable, lonely men – and a small number of women – with the promise of intimacy, and delivers only a transitory masturbatory fix. Increasingly, though, men are starting to be open about the effect pornography has had upon them. David McLeod, a marketing executive, explains the cycle: “I’m drawn to porn when I’m lonely, particularly when I’m single and sexually frustrated. But I can easily get disgusted with myself. After watching a video two or three times, I’ll throw it away and vow never to watch another again. But my resolve never lasts very long.” He has, he says, “seen pretty much everything. I’ve even seen pictures of men being buggered by a pig. But once you start going down that slope, you get very quickly jaded.”

Like many men, McLeod is torn. Quick to claim that porn has “no harmful effects”, he is also happy to acknowledge the contradictory fact that it is “deadening”. Andy Philips, a Leeds art dealer and, at 38, a father for the first time, says there have been times when he has been “a very heavy user”. His initial reaction, like that of many of the men to whom I spoke, is studiedly jokey: “I love porn.” Yet, as he grows more contemplative, he admits: “I’ve always used it secretly, never as part of a relationship. It’s always been like the other woman on the side. It’s something to do with being naughty, I guess.”

Again and again, despite now being married, he is drawn back. “You can easily get too much of it. It’s deadening, nullifying, gratuitous, unsatisfying. At one point I was single for three years and I used a lot of porn then. After a while, it made me feel worse. I’d feel disgusted with myself and have a huge purge.”