In the aftermath of Charles Roberts's grotesque theatre macabre in the Amish town of Nickel Mines, Pennsylvania, I was dragged on to radio and television to shed light on American "school shootings" - their provenance, explanation, meaning. As the author of the novel We Need to Talk About Kevin, I was a little embarrassed to be touted as an authority on school shootings, just because I had made one up. But, touch wood, the UK has yet to import this perverse and almost exclusively American pastime, and becoming an expert in school shootings would not have proved a lucrative career path for native Britons.

Having done a fair whack of research on my country's non-fictional school shootings, I was still only up to speed on the juvenile variety, and two of the three incidents that clumped alarmingly into a single week were perpetrated by adult men. Last month in Bailey, Colorado, Duane Morrison took hostage several school girls, whom he sexually molested before killing one and then himself. Charles Roberts tied up and shot 11 Amish girls, killing three outright and fatally wounding two before shooting himself. If only these miserable blighters would get the order the other way around.

But did it make sense to discuss the Columbine and Nickel Mines incidents together, just because they occurred in schools? Maybe. Whether by teenagers or grown-ups, these gory gun-toting tantrums have all been acts of consummate childishness. Hitherto, disgruntled adult lunatics in the States may have aimed their infantile aggressions at (often former) places of employ. But as my narrator in Kevin remarks: "Workplace massacre is school shooting grows up."

With minor variations, I noted that these incidents were obviously bids for attention - very public, media attention. Drunk on the same lethal cocktail of grandiosity and self-pity that intoxicates suicide bombers, school shooters meticulously plan their grand, apocalyptic gestures of defiance or despair; these are almost never acts of spontaneous rage. It doesn't require a professional imagination to deduce what churns their minds in the lead-up: the headlines, the exposés, the very news programmes in which I was myself participating. These visions are so exhilarating that even posthumous vindication appeals.

The whole world will share in their suffering, analyse their families and friendships, come to grips with their grievances - whether over bullying by classmates or the taking of an infant by God. These visions are quite accurate, too. That's exactly what we'll do.

Americans these days seem to crave public recognition, and it no longer appears to matter much what they're recognised for. Witness the raft of ever more daft US reality shows: clearly, Americans will do just about anything, no matter how humiliating, to get on TV. In my parents' day, the prospect of being cited in the local newspaper for doing something shameful was every child's nightmare, not his fantasy. But lately Americans are erasing the line between fame and infamy, aspiring to celebrity of either stripe. Admiration might be icing on the cake, but the greater goal is to be known.

Well, if all you want is to be noticed, notoriety is an astute short cut, isn't it? (The very word "notoriety" is increasingly misappropriated as a synonym for "fame" - we no longer, even linguistically, know the difference.) Winning the Nobel Prize for physics is a long shot, and takes years of education and toil. Shooting up a school takes a few weeks of scheming, and, for Charles Roberts, shopping for ear plugs and loo roll. If you want attention, and opprobrium will do, it's actually more efficient to shoot up a school than to make As on your report card or do an especially diligent job of collecting milk from farms.

Naturally, vengeance enters in. If we are meant to share the perpetrators' pain, we are also meant to bear the brunt of it. Any number of these incidents have amounted to what I call "extroverted suicide". All suicides engender an element of "You'll be sorry!". Suicides determined to take unwilling company along with them are jacking up the stakes: "You'll be really sorry!"

Yet my suppositions do not translate into a remedy. It is hardly realistic to propose that we therefore must deny the culprits the publicity they crave by fiat, in the hopes of dissuading would-be school shooters from conjuring similar packages on CNN about themselves. We cannot impose on a free press the obligation to bury news reports about mêlées that trigger parents' most primitive fears and universal anguish about the needless sacrifice of innocents.

For decades, the same self-perpetuating engine of media hype powered the troubles in Northern Ireland, where I lived for a dozen years. Avowed to deny the IRA the "oxygen of publicity", Margaret Thatcher banned Sinn Fein spokesmen from the airwaves. The result was farce: Gerry Adams on the BBC, his words read by an actor. By the time the counterproductive ban was lifted, the actors had the accent to a T.

There were periods during which IRA bombings grew so frequent that they subsided to background noise. By the same token, about the only "answer" to the celebrity dilemma of American school shootings is their becoming so commonplace that another one no longer qualifies as big news. Wince if you will, but after the barrage of such reports in 1998 and 1999, by the early 2000s that's exactly what had begun to happen: school shootings with lower body counts were slipping to the inside pages. But even the public boredom that sets in with overkill is a temporary fix. Americans are ingenious, and all it takes is another variation on the theme - say, adults like Charles Roberts aping his juvenile predecessors, with a sexual twist - and, voilà, the phenomenon is fresh again.

Oh, and mea culpa. A woman asked me at a reading last Thursday night whether Kevin didn't give yet more publicity to school shooters, and I cheerfully admitted to being a hypocrite. Me and my precious book and my appearance on Newsnight - I am part of the problem.

I'd still stand by those observations as plausible. Nevertheless, by the time I appeared on BBC News 24 towards the end of last week's ad hoc media tour, I had wearied of this "celebrity" shtick, and I was also starting to feel, apropos of that mea culpa, obscurely sheepish.

For her final question, the interviewer asks earnestly what "lesson" we might take from the Amish shooting. America needs stricter gun control? Unless the US improbably inverts its whole approach to civilian armament - i.e. you have to convince the police why you need a gun, as in the UK, rather than the police having to locate a reason why you can't have one - stricter gun control measures in Pennsylvania would not have prevented Nickel Mines. Charles Roberts had no criminal record. He had no psychiatric record; he was privately crazy. A "waiting period" between order and acquisition would have made no difference; he'd bought the semi-automatic pistol with which he shot most of those girls in 2004. Under the most stringent provisions of any American state's statutes, Charles Roberts could have bought a gun.

"Lessons?" I say. "We come up with lessons in order to make ourselves feel better." Camera cuts to next news item. My interviewer turns to me limply. "Well, that was depressing."

It is depressing. It should be depressing. And it should stay that way.

The urge to interpret - to draw "lessons", to use these freakishly gratuitous acts of malice as windows on American culture, to burrow deeply inside the psychological twists and turns of the killers' minds - might best be resisted. For the culprits use our need for meaning to magnify what deserves to be left small and squalid. They use our voyeuristic curiosity about what makes them tick as a weapon.

In initial reports about Charles Roberts, we learned that he was "angry at God" over the death of his own daughter, although the premature baby had died years before. According to the local police chief, the shootings were "vengeance" for something that had happened to our anti-hero 20 years earlier. At first I admired the police for seeming to withhold what exactly Roberts would avenge from the age of 12 - thus depriving the man of the posthumous public revenge that he had contrived for himself, even if the police were frustrating my own thirst for a coherent story.

Alas, later, the tale grew more garbled. At 12, Roberts was not victim but victimiser, having confessed to his wife that he had sexually abused two younger relatives at that age. More confusing still, the relatives in question deny that Roberts did any such thing.

But never mind all that. By what emotional logic do any of these biographical scraps lead to shooting 11 little girls?

The story doesn't add up, and I don't care. Perhaps we oughtn't try so hard to square the narrative circle. The normal, instantaneous reaction to the news of this killing spree - incredulity, disgust, incomprehension - is morally sound. If we don't understand, maybe we shouldn't.

For both journalists and their audience, drawing larger conclusions from these fitful explosions of spite is compulsive. There's a particular intellectual discipline required to repress the instinctive urge to interpret, for to find meaning where there is none is to distort. The impulse to derive "lessons" is an impulse to redeem the irredeemable. A deed beyond selfish to solipsistic, Nickel Mines - like Columbine, Pearl, Jonesboro, Bailey; the list is sadly too long to cite in full - was purely bad. It should not have happened. To take any more than that from plain awfulness is to glorify the tawdry, the deranged, the insensible - an act that presents itself at first as pathetic and that we should endeavour at all costs to maintain as pathetic.

Nickel Mines means nothing. That is the ugly truth that the Amish of that benighted town have to live with, and the pure nihilism of this atrocity is both their burden and their salvation. To force that shooting to mean something is to do Charles Roberts's dirty work for him. It is to do his bidding.