You had the sense that, after an hour's pushing, an enormous stone had rolled back to precisely where it had started from

According to Oliver James, who performed long range psycho-analysis on Radovan Karadzic in a recent edition of Leviathan, around five per cent of the population are psychopaths. Most people won't have too much difficulty in identifying candidates for this unpleasant elite amongst their own acquaintances. You might hesitate to describe them as "evil" precisely - after all, in many cases they haven't actually done anything wrong - but if you were suddenly required to recruit an office death squad you would have more than a vague idea of where to start. The task might be even easier than Oliver James suggests; one of the more cogent themes in Roots of Evil (C4)- an ambitious three-part study of what we actually mean by that much-abused word - was that the proportion of the population capable of committing terrible crimes is much greater than a mere five per cent.

"Most evil acts are committed by ordinary people" proposed the voice- over. This was a thesis whose concision and clarity you soon came to recall rather wistfully.

Rex Bloomstein's programme began as a something of a ragbag, a reminder of countless sixth-form debates about the nature of evil. "The overall aim of allowing Satan to get up to his tricks is to deepen and develop faith in God" said one cleric, given a few seconds to resolve a question that has troubled men for centuries. Quite apart from the evasive flippancy (does Auschwitz really count as a "trick"?) this strikes me as a singularly odious piece of theology - as if Dunblane and Rwanda were calculated moves in a strategy of divine self-interest. If these unhindered cruelties are a test of faith , then I fail. On the other hand, almost as glib, you have the simplicities of a sociological model, in which "parental deficit" and "sexual abuse" replace Satan and his minions.

After a slightly Benetton passage of international vox pops, Bloomstein went to visit two serial killers - both of whom seemed to cite their own awful childhoods as the origin of their crimes (though at least one of them thought that the label evil didn't apply to him anyway). An account of the Bulger case was similarly fruitless - contrasting a policeman who talked about "an aura" of evil around the two killers with a journalist who deplored such simplistic labelling.

It would be equally simplistic to expect a television documentary to deliver a ready-baked solution to such an intractable problem. But it didn't help that Roots of Evil was sometimes brisk to the point of indifference, particularly when it came to recent genetic research. "Can [genes] tell us about a compulsion to kill?" asked the narrator. A scientist took some 20 seconds to say no and we were on our way again: "If genetics doesn't explain human evil, what does?" I don't think this counts as a very profound survey of the fascinating arguments about the biological origins of human behaviour which have been explored in recent years by socio-biologists and brain-scientists.

The film ended more strongly than it had began, if only because it fielded a number of contributors who effectively said "there isn't a simple answer". In the accounts of the neighbourly atrocities of Rwanda and Bosnia it also became clear that the suppression of decent instincts and the encouragement of base ones can effect terrible transformations in quite ordinary people. Even so you had the sense that after an hour's pushing, an enormous stone had rolled back to precisely where it had started from.

I suppose some people might view Damien Hirst as evil, perhaps encouraged by that sinister forename and the sanguine gruesomeness of his art. He's undoubtedly an imp, as he proved with the first of five TV Sculptures, commissioned by Channel 4. Imagine that the screen is completely transparent so that you can see the entrails of your television set. Fill the space with buzzing flies which are randomly zapped by a fine bolt of electricity. Continue until almost all of them are dead. This piece was called "No God", which I took to be a comment on the arbitrary nature of fate. Then it dawned on you that this grim little universe did have a Prime Mover after all - and one with a very black sense of humour.