PAEDOPHILE riots in Portsmouth: it makes me think of witch hunts in Salem, Massachusetts in the 17th Century. But what is the meaning of all this hysterical violence? It goes without saying that sexual abuse of children is vile and depraved and that those convicted of such acts must be severely punished. But there are degrees of abuse, from the appalling murder of such as Sarah Payne to the merely squalid grope or fumble. Thankfully, the murder of children is a rare event.

It should come as no surprise to see that child sex abuse is always in the headlines. I don't know if there is more of it than there used to be, but there is certainly more discussion - if that's not too decent a word to describe the mob action of recent weeks - of it than ever. It went on when I was a boy, but it was the sort of thing that was mentioned only in whispers and euphemisms. I remember my aunt's shocked and embarrassed expression when she told me that a neighbour had gone to prison for "messing about with" his daughter. I could only guess at what she meant.

We were buttoned up in those days, but now we let everything hang out. The corrupt psychology that describes self-restraint as "repression" - which of course is "bad for you" - permits a whole range of sexual activities which a generation ago were regarded as perversions.

We should expect there to be more sexual abuse of children in a society which has become as grossly sexualised and coarsened as ours. Pornography appears on Channel Four regularly and on Channel Five most nights. And, when children can pre-programme videos rather more efficiently than adults, it's no excuse to claim that it only comes on after the 9pm watershed. Every evening there are films on TV depicting simulated sex. The soap operas watched by millions of the least educated and therefore most susceptible people have storylines full of adultery, fornication, rape and incest.

It goes much further. TV advertisements use sex all the time to sell everything from motor cars to washing powder. The children's programmes themselves promote sexual activity and create the impression that everybody's at it all the time. Many newspapers - particularly those that take such a high moral line about child sex abuse - feature half naked teenagers across their pages. Even more serious newspapers think nothing of having an editorial bewailing the moral decline of the nation next to a feature advising women how to look sexy on the beach, or how to conduct an office affair.

Sex has not only been made more blatant, it has been extremely coarsened by the universal use of the four letter words which were once taboo. And, where films of a generation ago suggested sex as something tender and romantic, today's "in yer face" culture frequently portrays it as involving aggression. Moreover, sex is no longer a sacramental coupling, but a consumer durable: people don't "make love" any more; they "have sex" -like they have a hamburger.

The point is this: for centuries the Judaeo-Christian moral teaching about sex was social orthodoxy. Of course people transgressed its commandments, but at least sin was recognised for what it is. Now the old ethic has been abolished and with it the concept of a difference between right and wrong. No wonder public life is a foul and pestilential congregation of vapours - just the sort of atmosphere in which all kinds of depravity, including the abuse of children, thrive.