`My Stalker Hell by Pammi Girl", says The Sun's headline. Beneath is a picture of "lovely Perry Southall, 20" wearing a PVC miniskirt and boots. Ms Southall, it ought to be explained, is Pammi Girl, as far as The Sun is concerned, because of her striking resemblance to Pamela Anderson, an actress. She was stalked for eight months by a man who was finally convicted on two assault charges - the jury accepted that she had been psychologically scarred.

Meanwhile, Doreen Holt told delegates at the Liberal Democrat conference of the way her daughter's life had been devastated by a man who stalked her for five years. Moved by the speech, the conference voted overwhelmingly to make stalking a criminal offence. The judge at the trial of Clarence Morris, the stalker of Ms Southall, also called for legislation.

Plus, of course, there have been some high-profile Hollywood cases of stalkers-to-the-stars. One way or another, stalking appears to have crept furtively on to The Agenda.

Legally, one can see the point. Being obsessively stalked must be appalling and anybody who causes such anxiety and misery ought, on the face of it, to be prosecutable. But this is tricky. At what point would a certain pattern of behaviour become stalking? And what is wrong with stalking if no threats are made and no harm is done? Well, obviously quite a lot, but once you create offences defined by the subjective response of the victim, it becomes difficult to know either where to stop, or what would constitute evidence. And, after all, Clarence Morris was convicted, so the present law seems to be fairly usable.

But the current fascination with stalking is not really about the law; it is about totems and taboos. The big totem is sex. The big taboo is bad sex. Penny Southall, because of her resemblance to a tabloid heroine, is good sex. Clarence Morris, because he turned up at the dental surgery where she worked wearing Y-fronts outside his trousers, is bad sex.

This distinction is crucial to the functioning of a society that thinks of itself as liberated but is, in fact, more elaborately enchained than ever. Sex sells things very successfully so there are big vested interests involved in promoting sex. Advertising, newspapers, television and films all now routinely use material that, 50 years ago, would have been regarded as hard pornography. And all of this sex is good, healthy and fun, an essential part of contemporary identity, because, if it weren't, it would not sell the cars, newspapers, whatever

But, liberated as all this may seem, it has to be held together by some highly puritanical injunctions. The tabloids, for example, will reserve the right to expose any sufficiently prominent adulterer, especially if there is anything "kinky" involved. Such a "love rat" or "pervert" is somehow deemed to offend against the totem of good sex, celebrated elsewhere in the paper by bare-breasted models and sex advice columns and features.

The glaring discontinuity arises from the attempt simultaneously to regard sex both as a simple appetite and as an emotional and moral force. The first decorates the culture, the second gives it something to talk about.

On the one hand there is the fantasy world of good, clean sex between attractive young people; on the other, the real world of the old, ugly, infirm or just averagely attractive individuals for whom sex is never simple.

The idea that the fantasy world may have some adverse impact on the real world is not something the fantasists like to think about. David Stanton, Morris's barrister, tried to defend his client by, effectively, saying that Southall had only herself to blame because of the way she looked and dressed. This was a stupid move. Clearly Stanton's ill-judged words implied a connection between the Pamela Anderson fantasy and the grubby reality of the stalker.

But, of course, all sane people know the connection is real enough. It is inevitable that inadequate people are going to be aroused to unacceptable extremes by the daily deluge of images of an inhumanly perfect sexuality. The stalker is just somebody who tries to live out the fantasy he is being sold. This doesn't make him any less guilty. But it should make some people think carefully about the flagrant lie that sex is a simple physical appetite.

So stalking is on The Agenda precisely because it is an activity that seems to be a direct response to the world of fantasy sex in which we all now live. The stalker is at a distance, looking, drawing constant attention to his victim as pure surface, a mere fantasy image. He provokes outrage because his presence implies that his victim can be reduced to a version of a media star. He excludes her from the communal sexual fantasy by threatening to make it real.

It is hard to imagine a neater image of the contemporary experience than this threatening confrontation between fantasy and reality. No wonder the stalker has become one of the anti-heroes of our time.