This may be partly because the British have a peculiar fascination with murder - witness their invention of the genre of the whodunit and their penchant for always having a Queen of Crime (at present a dual monarchy, shared between Baroness James and Baroness Rendell). But it is partly because morality cannot exist in the abstract. It needs cases, exemplars, to feed on.
Thus, the murder of young Jamie Bulger became a matter of public anguish about what might be happening in the underclass zones of British cities. The murder of Stephen Lawrence became a slow-burning fuse that eventually ignited a fierce debate - and some action - about the question of racism in Britain, 50 years after the great post-war migration had begun. Both murders were, of course, made all the more poignant because the victims were themselves defenceless and wholly innocent of any involvement in violence.
Which will be the next murder to be seized on in this way? So far, the terrible death of 71-year-old Lily Lilley in the bedroom of her house in Greater Manchester has been treated, mostly, as just a source of horror and contempt. On Tuesday, at Manchester Crown Court, two 15-year-old girls were found guilty of the murder, and ordered to be detained at Her Majesty's pleasure.
They had befriended the frail widow, then gagged her so ferociously that she choked on her false teeth. They slashed her with a blunt knife and pushed her body in a wheelie bin through the streets before dumping it in the Rochdale Canal. They made 258 telephone calls from Mrs Lilley's house and carved their names on the walls and the furniture.
The girls wept as they were sentenced, in a courtroom which, after the Bulger murder, had been reorganised to be less fearsome to young defendants. The lawyers and the judge wore no wigs and no robes. But the sentence was the same.
Manchester prides itself on having pulled itself up by its bootstraps. It is eulogised in Lord Rogers's Urban Task Force report. But much of the improvement is confined to the innermost city. Mrs Lilley was killed far from the centre, in the Failsworth district, between Oldham and Ashton- under-Lyne. In these former cotton towns, work has simply collapsed. If you want a walking, talking illustration of a breakdown of social norms, you can go on an "Anomie Tour" all round Greater Manchester. The murder of Mrs Lilley was, in its way, Kosovo come to Britain - the elderly woman was seen as fair game.
It could all provoke debate about the increasing isolation of many older people, living on their own. But these girls' folie a deux is more likely to evoke feelings of sheer disgust and horror. The old tussle between nature and nurture re-emerges, as it also did over the sentencing of 19-year-old Dominic McKilligan, last Friday, for the rape and murder of an 11-year-old boy in Newcastle.
And so it should. To say that social environment determines everything is an insult to those who remain unbowed by early poverty, or lack of love, or all the usual assaults on a happy childhood. Nature intervenes in nurture. We could argue about the percentage. We could also argue about whether to call a bad hand of genetic cards "evil" or simply "disadvantage".
Faced with a murder such as Mrs Lilley's, most people would plump for "evil". It is simpler and less namby-pamby. It also confronts the difficulty of doing anything by way of rehabilitation, unless the criminal undergoes something close to a spiritual conversion. Nobody knows whether the two girls will experience such a conversion where they are now going - though the case of Mary Bell, perpetrator of another "exemplary murder" but now released, may give grounds for hope.
It is essential to cling to hope, rather than sink into despair. This week Sarah Curtis, with 20 years' experience as a magistrate, publishes a timely and closely argued study, Children Who Break the Law (Waterside Press, pounds 16). In spite of all the young people on whom she has sat in judgement, Mrs Curtis is not case-hardened. She rejects the argument that "nothing works". Building her own argument around detailed interviews with young people who have come before the courts, she is an advocate of hope.
She applauds Jack Straw for much of his Crime and Disorder Act, 1998, and his Youth Justice and Criminal Evidence Bill. But she calls for "a change of emphasis from endless, vengeful discussion about what to do with young offenders to passionate concern for preventing them ever offending in the first place". So many, she notes, live in a world where, they think, "Everybody does it". A girl shoplifter she interviewed speaks of crime as a kind of addiction. Sarah Curtis fears, with good reason, that none of the Home Secretary's reforms will get the money to do the job properly.
She is not, she acknowledges, talking about "those guilty of the gravest crimes". Hard cases make bad law; and the worst of crimes, such as the murder of Mrs Lilley, are not amenable to calm discussion of what might help prevent the great morass of petty and middling crimes. Trying to keep children in school (rather than truanting), teaching them how to be good parents (rather than muddling through), focusing on the difference between right and wrong (rather than infinite, misplaced sympathy) - none of this connects with such a crime.
What is exemplary about the series of evil acts in Failsworth is its rarity. We must not let our justified shudder of dismay divert us from attempting to do the best we can with, and for, the great majority of those who go wrong.
Sarah Curtis's shoplifter interviewee said : "If I had kids of my own, I'd tell them it's not worth it." But after the interview she was arrested yet again. The core of the argument is : How can we make sure that other young people learn their lesson earlier - and that the lesson lasts? If petty crime less often builds up to murder, we should be duly grateful. But sights set lower are more likely to hit the target.
The writer is a senior Fellow of the Institute of Community StudiesReuse content