Harold Shipman hasn't quite made it as an icon of evil. The nondescript doctor who murdered dozens, maybe hundreds, of his patients has escaped the pantheon of moral monsters because of the sheer opacity of his personality. He was a serial killer on an almost unthinkable scale, but the colourless figure waving at the camera in endlessly repeated media footage has yet to become a popular signifier of moral horror. His murders were methodical, even orderly, and showed no obvious signs of sadism. Perhaps they satisfied some secret need for total control - but by committing suicide, Shipman ensured that his motivation will remain unknown for ever.
The images of Shipman that have been disseminated do not lessen the mystery that surrounds his crimes. The incessant clips in which he is seen coming and going in his driveway seem to record an eventless existence, an unending round of stilted gestures that are as hard to read as his crimes. He seems to have been decomposed into a succession of jerky movements that reveal no sign of personal agency. This blank illegibility blocks any simple judgement of wickedness. It is perhaps for this reason that Shipman has so far eluded representation in art.
In contrast, the police mugshot of Myra Hindley in heavy make-up and blonde wig is a caricature of female depravity. (Despite having had no direct part in the deaths of Jessica Chapman and Holly Wells, Maxine Carr seems destined to be cast in a similar role.) The photograph of Hindley formed the basis of Marcus Harvey's painting Myra, in which it was magnified using a child's hand print instead of the dots from which it is constructed in newspaper reproductions. Predictably, and no doubt intentionally, the painting sparked a noisy debate when it was shown in the "Sensation" exhibition of Young British Artists at London's Royal Academy of Arts in 1997. The tabloids seized on it as an example of the degeneracy of contemporary culture, but by doing so they were instrumental in promoting a new genre, a highly commercial mix of the ironic and the pornographic in which evil is merely another way of interrogating our values.
A stylised nihilism pervades the culture, but when it becomes an unthinking reflex, nihilism ceases to be cathartic. There is a world of difference between Francis Bacon's savage assault on meaning and the cool detachment that is expressed in Harvey's Myra. Bacon's paintings derive their energy partly from a sense of loss, but it is just that which is absent when nihilism becomes a commodity manufactured and marketed by the culture industry. A mixture of affectless violence with the ephemera of fashion and advertising has created the most successful brand in recent British art, but it is not a formula that can be sustained for long. The lightly subversive juxtaposition of images works only against a background that is heavy with meaning. Nihilist art requires a world in which traces of significance can still be found, but its effect is to wear away the few that remain. The end-point is an aesthetic of emptiness, in which everything is recorded and nothing felt.
While the dominant trend in recent British art has toyed with nihilism, the mass media have done the opposite. Technology has been used to manufacture meaning. The camera gives us a snapshot of events and allows us to imagine we are seeing things clearly and plainly. By turning the chaos of sensation into a series of definite images, it enables us to find meaning when it may in fact be fugitive, or even absent. The truth is that we do not know why some people commit hideous crimes, but living in this knowledge is intolerable because it leaves the world a random place. The media cater to our need for order. When the camera is used to construct an icon of evil, it is not simply giving vent to punitive fantasies, but being used to maintain meaning in our lives.
There is an analogy here with reality television. In programmes such as Big Brother, the contestants are under observation in practically everything they do - a fact that confers significance on what are essentially meaningless interactions. Under the camera's benign, unblinking gaze, the most sterile behaviour seems significant. The people who take part in reality TV do so because they find it more meaningful than their actual lives. In this, they are only responding to the logic of the time, which dictates that individual experience has no substance until it is rendered into the universally accessible stuff of the media. Without the validation that comes from being under continuous observation, their lives are illegible to them.
The proliferation of CCTV throughout society answers to the same human imperative. The rise of the surveillance culture is often seen as a response to the breakdown of social control that occurs as older types of community are replaced by more fragmented and anonymous ways of life. No doubt it does serve this need, but it is also a defence against the collapse of meaning. Like photographs of atrocities, CCTV images of the events preceding a crime are a form of memory. In the recent past, CCTV has served to memorialise intensely felt moments - most poignantly, perhaps, the clip of James Bulger being led unknowingly to his death. That unforgettable footage captures a child's view of the world as a place of safety, fatally threatened by the intrusion of evil. Yet the child's killers were themselves children and belonged in the same intractably dangerous world as their pitiful victim. We force ourselves to look at these images because we do not want the hideous loss they record to be forgotten. They rarely enlighten us as to the causes of the events they record, and they may well fail to prevent their recurrence, but they enable us to think that the collapse of values is not final and complete.
The demonisation of certain criminals is only an aspect of a much larger development. The media are taking over the labour of making meaning from the raw data of human experience - a task once assigned to priests and later to artists. The worst crimes may sometimes be no more than the last link in a chain of chance events, but in the iconography of the tabloids they are the work of moral monsters bent on unspeakable evil. Passing over the oblique connections that shape every human life, the media turn the obscure gestation of crime into a comforting morality tale. In doing so, they are not simply catering for a prurient obsession with the darkest human impulses; they are fending off meaninglessness. The demonology purveyed by the tabloids is often repellent, but in the final analysis it is a degenerate form of religion, an attempt to exorcise the spectre of nihilism.
John Gray is the author of Straw Dogs: thoughts on humans and other animals (Granta)