Pornography has infiltrated mainstream culture and threatens to escalate sexual violence. In her first article for a British newspaper, Catharine MacKinnon, who along with the late Andrea Dworkin led the crusade against the sex industry, looks at why we appear intent on turning a blind eye to what is right in front of us

The belief that pornography inhabits its own physical and mental world is an illusion. Nothing restricts its effects. Yet the protective myth of its spatial separation and cognitive confinement endures, even as pornography visibly takes over more and more public and private space, invading homes and offices and transforming popular culture.

There is such a thing as pornography, as its producers and consumers well know. No one is making tens of billions of dollars from, or masturbating to, the Bible, for example. This is only to notice that the pornography industry and mass media have long operated in separate spheres defined by content. In the name of taste, values or division of labour, legitimate cinema, books and media have traditionally eschewed or coyly skirted the sexually explicit. The "adult" movie industry, cable television and "men's entertainment" magazines have frontally specialised in it. This mutually clear line, quite precisely and effortlessly observed in practice, coexists with the common cant that pornography cannot be defined or distinguished from anything else.

Pornography is increasingly breaching this divide, making popular culture more pornographic by the day. This effect is routinely observed and sometimes deplored, whether for sexually objectifying women yet more inescapably or for taking away the sexiness of the forbidden. But if this movement is rarely documented, and even more seldom explained, the fact that pornography itself has been a popular feature of culture - the most mass of media - for some time is never faced.

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Society's ideology of compartmentalisation - that the rest of life can go on unaffected - never seems to be embarrassed by pornography's ubiquity. It has been in plain sight all along. In reality, pornography's place is just down the street, right there on the rack in the convenience store, not to mention in the bedrooms and bathrooms of homes where its users seldom live alone. Yet even as the industry has burgeoned, taking over more public space and penetrating more deeply into private life at home and at work with each advance in technology, it is considered to be somehow not really there.

The same dissociative logic structures the legal regulation of pornography.

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Obscenity, one meaning of which is "off stage", is located in some neighbourhoods and not others. The question of where is politically fought over locally like the placement of noxious waste, as if its effects can be so confined. Pornography has to be somewhere, the attitude is, the only question is where. (One reading of the law of this subject in the US revolves around how far a man has to travel to get his fix before it becomes unconstitutional.) Pornography is considered addressed by the legal sleight of hand through which it is imagined placed in some demimonde: over there rather than right here.

Beyond the geographical, the psychological disconnect is perhaps most socially potent: the delusion that pornography is "fantasy". No woman was ever ruined by a book, as the slogan goes. This gives using pornography a certain deniability. Never mind that someone has to be sexually used to make the visual materials that form the vast majority of the industry's output. Never mind that among the first and most robust of the results of consumption is the spontaneous generation of rape fantasies, or that people often do what they imagine they want to do. Never mind that "fantasy" is the word used by a man convicted of being about to make a snuff film of a boy to describe the detailed plans he was intercepted discussing or what the media reported a man was having with a prostitute whom he drowned in a bathtub.

One telling episode in these annals of denial arose in the publication of American Psycho , an upmarket high-concept work of fiction in which one woman after another is sexually slaughtered. Women are skinned alive, mutilated, raped and one dismembered head is used for oral sex, all in graphic and explicit terms. Simon and Schuster, in an exceptional move, rescinded its contract of publication shortly before the book was due out.

It was rumoured by insiders that women on the staff refused to have it published in their house.

The publishing industry has long coexisted with - at times affirmatively defended - the pornography industry. This includes the film Snuff , a sex movie available since 1972 right down the street from Simon and Schuster, in which a woman is shown being disembowelled while alive. The shock of, hence the opposition to, American Psycho was apparently that it was here, in mainstream publishing. As long as sexual killing is happening "over there", it is as if it is not happening at all. American Psycho seemed to shatter that illusion of context for some people, at least momentarily. The book was quickly bought and published by Vintage, a division of Random House.

A similar magical framing move occurred in connection with the scandal surrounding Abu Ghraib. The photos of naked Arab men being abused by American soldiers while in their custody were routinely termed pictures of torture and sexual humiliation in the press. If the fact that the photos were identical to much pornography (although mild by its standards) was noticed at all, it was more often to excuse the crimes than to indict the pornography. Then a mass-market US newspaper was duped into publishing photos said to be of an Iraqi woman being raped by American soldiers that turned out to come from pornography. The public was upset by the pictures - until they found out that it was pornography. The newspaper apologised for not properly authenticating the picture.

The photos, had they been what they were thought to have been, would have documented criminal atrocities. The identical picture, framed as pornography, became masturbation material that a legitimate outlet had been cleverly tricked into putting on its front page in another blow for sexual freedom of expression. As pornography, the conditions of its making - who was she? how did she get there? was she being raped? - were not subject to inquiry. They never are.

The assumption that the violence, violation and abuse that is shown in pornography is somehow "consensual" is just that: an assumption. It coexists with much evidence of force and coercion, beginning with the materials themselves. Mass emails advertising photos of "hostages raped!" are spammed to internet accounts without generating inquiry into whether they are either. A website called Slavefarm offers women for sale as "sexual slaves", complete with contracts signing away all human rights and explicit photographs of the slave being tortured. Authorities stonewall.

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Live feed provides direct sexual use of prostituted women onscreen. No matter how real and harmful it gets, pornography, in reality a form of trafficking in women, is this parallel universe in which everything that happens becomes harmless and unreal.

Long overlapping sub rosa with legitimate entertainment, pornography has been a criminal underworld pursuit. Making it still is. But as it has exploded - the industry was said to gross $4 billion a year in the 1980s, between $10 billion and $14 billion in 2001 and by 2005, adult video rentals alone were estimated to earn $20 billion a year in the US, $57 billion globally - its distributors no longer live under rocks. Legitimate corporations now traffick pornography, often through subsidiaries, their financial stake as immense and established as it is open.

Certainly the level of threat and damage to women's status and treatment and to equality of the sexes worsens as pornography goes mainstream and becomes seen as more legitimate. Venue does matter. That does not mean that pornography has not been a dangerous, damaging and real part of social life all along. If its effects do worsen the more widespread and visible pornography becomes, the view - as tenacious and pernicious as it is baseless - that it has no effects as long as it stays underground has made its march into the open possible. If the spatial separation of pornography into its own little world has been dubious, its mental isolability is pure delusion. Pornography changes its consumers, who then go everywhere under its influence. Nothing contains them.

Excellent social science research over the past 25 years has documented the effects of exposure to pornography, providing a basis to extrapolate the predictable consequences of mass social saturation. The catharsis hypothesis - the notion that the more pornography men use, the less abusive sex they will seek out elsewhere - has been scientifically disproved.

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Closer to the reverse has been found: it primes the pump. As women have long known, use of pornography conditions consumers to objectified and aggressive sex, desensitising them to domination and abuse, requiring escalating levels of violence to achieve a sexual response. Use of pornography is also correlated with increased reports by perpetrators of aggressive sex and with increased inability to perceive that sex is coerced. Consumers thus become increasingly unable to distinguish rape from other sex. Some become addicted, virtually none is unaffected, the evidence as a whole suggests.

Consuming pornography, with some individual variation, produces attitudes and behaviours of discrimination and violence, particularly against powerless others. By extension, the more pornography is consumed, the more difficult it will become, socially, to tell when rape is rape, even for some victims. An increase in sexual assault, accompanied by a drop in reporting and low conviction rates, is predictable. All this has happened.

Mass desensitisation of a major segment of the viewing public has a corresponding effect on the rest of popular culture. The audience for popular culture is the same as the audience for pornography. Ten winos in raincoats are not producing the industry's revenue figures. Popular culture, from advertising to legitimate film and books, has to become correspondingly more explicitly sexual - specifically more sexually aggressive and demeaning to women - to get the desired rise out of the same audience. Advertising is a particularly sensitive barometer of this effect.

How that public buys, what it demands, how it responds and what it wants to see are being significantly controlled, skewed by pornographers. Soft pornography blurs into light entertainment. The powerful conditioning of huge proportions of the male public makes them demand that the women around them look and act in conforming ways. We increasingly live in a world the pornographers have made.

High culture is affected as well. Women writers who present young girls loving being sexually initiated by old men, daughters feeling ambivalent about sex with their fathers, pornography being part of the old world of freedom rather than a future dystopia of totalitarianism, rocket to success. It is not that they are not fine writers. It is the fact that their work converges with pornographic conditioning, affirms it in a classy woman's voice, that catapults them to the top, makes their work suddenly catch on as exciting. It is the moment of and precondition for their success. Academic women who breathlessly defend pornography benefit from the same response. Criticising pornography, or writing so that rape is experienced by the reader as abuse, produces the opposite reaction: detumescent shunning. When feminists unmask pornography effectively, those who support it suddenly become favorites du jour . It works for men, too.

Excuse sexual assault ever more openly, present women who oppose pornography as befuddled if well-intentioned moralists, attack serious approaches to the problem as evil censorship and you too may receive a Nobel prize for literature.

Tracking the escalation in sexual explicitness and sexual violence in mainstream cinema is child's play. More to the point, why was Sharon Stone's vaginal flash in Basic Instinct so electrifying, such a sensation? Far more than that was available in any soft-core pornography film or magazine right down the street. It was context: a mainstream actor, doing it here, in a mainstream film in a family cinema. Breaking the frame on sex gives a frisson of power, it seems, for which you first have to believe that the frame is there. Why was it shocking when Janet Jackson's breast popped out in a dance-attack on her in the Superbowl halftime show? Playboy has scores monthly, page three at least two a day. Context: a mainstream singer, here, in family time during one of masculinity's public ritual events. Audiences are thrilled, scandalised, titillated. Barriers broken.Pundits juiced. Territory gained. Freedom reigns.

Who pays? Stone was told when she shot that scene that the footage would not be used (hence its grainy first-take outtake quality); she reportedly suffered considerably when it was. Jackson more or less apologised for the "wardrobe malfunction". However they felt, they had to be good sports for the sake of their careers - just as Paris Hilton did when pornography of her was released. Pornographic portrayals of feminist anti-pornography writer Andrea Dworkin lowered the floor on how she was seen and treated for life.

In pornography, women are publicly construed as members of an inferior sex-based group and constructed, some individually, before they are ever known personally. Sexual arousal, excitement and satisfaction are harnessed to that portrayal, reinforcing it, naturalising it, making it unquestionable and irrebuttable. So, too, for all the nameless women used in pornography - society's "whores". Pornography is a mass instrument for creating how women in general, specific women and groups of women in particular, are seen, treated and received. It constructs their status as unequal and their reputation as inferior. Few weep for a "whore's" reputation.

Meanwhile, progressive people, whatever they really think, defend pornography's right to exist and other peoples' right to use it, in tones pious and terms high-minded. Esoteric debates about aesthetics and causation take place amid periodic convulsions of moral fervour, producing occasional convictions for obscenity or restrictions on indecency. The industry shapes itself to law, and, more crucially, law to it. Most fundamentally, pornography changes culture to protect its existence and extend its reach, so finally it will be true that there is no distinction between pornography and anything else. The best camouflage of all is being able to lie around in plain sight.

People who do not want to be accosted by pornography visually are expected to avert their eyes. Having fewer and fewer places to avert their eyes to, with fewer means of escape in public and none in private, women specifically - who are most endangered by these materials and often know it - are segregated, painted into ever smaller corners. The female version of the male compartmentalisation myth is, "pornography has nothing to do with me". Pornography is thus at once increasingly everywhere and yet protected from direct scrutiny and effective abolition by seeming not to be there at all.

In 1983, Dworkin, who died recently, and I proposed a civil law that would empower anyone who could prove they are hurt through pornography to sue the pornographers for human rights violations. We defined pornography as what it is - graphic sexually explicit subordination of women through pictures and words that also includes specified presentations - and defined causes of action for coercion, force, assault and trafficking. We documented its effects and predicted its impact if nothing was done. Our law was found unconstitutional in the US in a ruling that held that pornography had to be protected as "speech" because it is so effective in doing the harm that the opinion conceded it does. Since then, although the law could have been re-passed and this blatantly wrong and arguably illegal ruling challenged, pornography has not only exploded, it has changed the world around us. Even the determinedly blinkered cannot evade noticing. It is colonising the globe.

The pornography industry is a lot bigger, more powerful, more legitimate, more in everyone's face today than it was a quarter of a century ago. To the degree that it cannot exist without doing real damage, it could still be stopped in its tracks anywhere by this law. Sexual objectification and violation does not happen all by itself. Real social institutions drive it.

Pornography does, powerfully, in capitalist mass-mediated cultures. If nothing is done, the results will keep getting worse. We told you so.

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Catharine A. MacKinnon is Elizabeth A. Long professor of law at the University of Michigan and co-author with Andrea Dworkin of P ornography and Civil Rights: A New Day for Women's Equality and In Harm's Way: The Pornography Civil Rights Hearings , published by Harvard, ?19.95.