Of all the works presented in 'Freeze,' the group exhibition curated by Damien Hirst in 1988, one in particular stuck in the mind. But also, perhaps, in the throat. A lightbox showed a colour close-up of blood and hair: the top of a head, at the centre of which lay a gaping wound. The title, Bullet Hole, did little to allay anxiety: the subject was obviously a severe head-wound before treatment. Nor did the grid, formed by the separate light-boxes on which the sections of the entire image were presented. Admittedly they were in the right order, but in this case perhaps the brain took longer than usual to assimilate the information. Nastiness was already a characteristic of Mat Collishaw's work. His B.A. examination at Goldsmiths' College, London had been tortuous: for days a single examiner held up the marking process not by giving him a low mark but by refusing to award him any mark whatsoever. But by the time a decision had been reached, it was already irrelevant. Collishaw had begun as he meant to go on, concentrating on the problematics of the image. The examiner was right to be apprehensive. In the course of the last seven years, however, Collishaw's thoughtful approach must surely have removed any apprehensions about his seriousness. He has used art to discuss important moral issues, not least of which is the problem of what that term 'morality' might mean.
Photographic practice has its own unwritten code of decency. Collishaw decided to defy that code and see what happened. 'Sensationalism' was the predictable objection to his gridded head-wound. Shown one by one, his lightboxes of Downs Syndrome children were less easily categorised. At first sight the children's demeanour seemed foreign, their expressions obscure. What could be expected from such portraits except (perhaps mutual) feelings of alienation, tension and non-communication? As usual, presentation was integral to the work. Fixed onto thick lightboxes by the same screws that kept the glass in place, the children, their likenesses printed on flimsy paper, seemed confused and embattled. As usual, Collishaw was operating in a zone of extreme ambiguity. In the case of the image of a black woman's face taken from a magazine, cropped and developed in such a way that it became abstracted and seemed white, the aim was to encourage viewers to suspend judgement, not only when looking at art. In other words, to help them realise that art can undo the usual reactions of viewers to photographic images: the categories they occupy, the rhetoric they promulgate, the beliefs they are assumed to support.
In the same year an untitled Collishaw work from 1990 featured in the group show 'Modern Medicine.' It consisted of three slides of a woman, projected onto the wall of an old biscuit factory. As usual with Collishaw, the image was hard to approach, in this case because the walls were still covered with pipes, switches, metal ladders and other impedimenta. Only from a distance was it possible to recognise the three-panel projection as depicting a woman - the same woman in each case - wearing skimpy, 'glamorous' clothes, smiling and bending forward, not out of choice but because she was in chains, her back pinned uncomfortably against the ceiling, which Collishaw, with Mannerist conceit, equated with the ceiling of the building in which the work was shown. On either side the same image appeared, reversed, while in the central panel the model looked straight at her viewers, smiling nervously to confirm the suspicion we were meant to cherish: that she was truly uncertain of her fate. Perhaps her apprehensive expression was the result of years of practise, its function being to transfer power and responsibility to her unseen partner, played in this case by the male, heterosexual viewer.
How difficult it was to know how to respond to that trio of giantesses in their old-fashioned outfits. And how incongruous to realise that the 40s cheesecake photographer who hit on a neat formula for a centre spread had unwittingly repeated one of the oldest ideas in the book: Christ, crucified between thieves. Alienation and fascination, vague attraction and powerful bad taste vied for dominion in this work, untitled as if it were decoration. Photography, like sex, may involve nothing but a play on conventions. Bored by this, Collishaw reserves his fascination for areas where conventions break down or, indeed, where none exist. (20 years ago, perhaps less, the very act of photographing a Down's Syndrome child was interpreted as an act of unkindness or scorn.) A similar approach underlay a set of photographs made in 1992 and called Period. Photographed in colour, and consisting of shots of women using sanitary towels, shown naked from the waist down, it occupied a genre of its own, like wartime films warning men in the forces of the dangers of venereal disease. The presentation is as telling as the images in this odd, anonymous-seeming set, dated in more ways than one, since as an artwork it thrives on an old-fashioned concept of the avant-garde, setting great store by rule-breaking for its own sake. Another interpretation would be as a classic 'misunderstood' reaction, a way of thinking which recent interpreters have traced to the Situationists and from them to Punk. ('If I am sick,' Collishaw told one interviewer, 'I think it has to be because I am the product of my environment, the society in which I live.') Darkest of all of his statements is the Suicide Suite from 1993, consisting of rephotographed images from police files of suicides, a reminder of the odd status of photographs in general, in this case half-documentary evidence, half-'art' - the halves, however, failing to combine in any way. Here, as always in his work, Collishaw emphasises perfect presentation, in many cases the continual aestheticisation of material which is unpromising, unpleasant or just 'sick'.
He speaks of the 'pregnancy' of the images that haunt him. In 1992, Egg, a close-up of an egg, demonstrated what he might have meant: the promise of some kind of development or manifestation. Following his practice of allowing the mise-en-scène to form part of the meaning, a slide of a close-up of a single, white egg was projected onto a piece of frosted glass lying at 90 degrees to the floor. (Because the slides wore out and had to be changed time and again, the projector contained nothing but copies of the same image, an image which would only just fit the opaque surface.) In the same way a wall-sized collage was made by offsetting male body parts, so many and so confusingly that the result could be read either as a warning against homosexual promiscuity or conversely as a celebration of that sexual persuasion - in the artist's own words, 'a gay frieze'.
Freedom became a preoccupation once more in the later video of a hamster: a household pet which runs around perpetually, in a treadmill provided for its exercise. Yet the most troublesome example of conventions breaking down occurs in Collishaw's I'm Talking Love (1992). The work is taken from Jonathan Kaplan's film The Accused, based on a true story of a girl, played by Jodie Foster, who hangs around a bar, enjoying the evening, smoking joints, acting in the same way as the men who surround her. When she is raped, whose fault is it? Men are animals, and will behave as such. That is the old argument against the girl's - or indeed any woman's - insistence on doing as she pleases. It most resembles a question which recurs in debates on crime and punishment: of whether responses are innate or inherited.
Freedom of choice can be fatal, of course. Dawn Chorus, that offending image from the Goldsmiths' degree exhibition, consisted of a police photograph, etched on glass, of a dead woman found headless under a bush. Like a bad dream, it has recurred in different places and different versions throughout Collishaw's career. Later it was retitled Sleeping Beauty and shown as a double image. ('One for each eye', the artist explained.) Indeed, at this point, the invitation to interrogate the image was constant. It even extended to Collishaw, who photographed himself as Narcissus, gazing at his own reflection in a pool. But instead of an idyllic, pastoral setting, the scene was acted out in an alley, where he lay shirtless on the muddy ground, as absorbed in his own beauty as any true narcissist. No matter that the water was muddy, the background urban, the site a narrow passageway with paving-stones and concrete bollards rather than tree-stumps and green sward; the motive was desire and the Barthesian punctum lay between the artist's legs, the point at which his fist, gripping the button of the shutter release, served also to conceal his genitals. No stronger statement could be made about the mendacity of the photographic image or the role of objectivity in art.
Evident throughout Collishaw's work, the idea of seeing things for what they are seems to matter more and more. Nobility through abjection is part of his aesthetic, after all: of rule-breaking apparently for its own sake, of photographing women inserting tampons or lying dead, raped and headless. Punk attitude is the ideal prelude to a meditation on the futility of existence. In the same vein, for example, Collishaw made a video loop of a pet canary in a cage, referring to the famous painting by Joseph Wright of Derby, a bird, flapping its wings prettily in a bell-jar. Prettily but desperately: in an experiment, the air had been drained from the container and the bird was dying as a result. A third work with birds, called Bird-Song Cycle (1993), also involved learned behaviour. Budgerigars were placed in a large cage, with a microphone transferring their singing to a reel-to-reel tape recorder, which in turn transferred it to another, which, by means of speakers outside the cage, played back the recorded sound after a three-second delay. It is hard to imagine the reaction of the birds, who perhaps recognised not only the song but also their own voices singing it, a feeling that may bring comfort, for they might be fooled into imagining the possibility of release. That no possibility exists is no one's fault. Recently, Collishaw has returned to the same theme of illusion and desire. A mirror on the front of a wardrobe was replaced by a two-way mirror, and a photograph of a forest scene was installed inside the wardrobe. The result was frustrating; walking towards it meant seeing it disappear. Freedom is nothing but an illusion, Collishaw suggests, and not for the first time, though he proceeds with the charade of conjuring that very illusion. And illusions are on his mind.
For a few weeks every year that effusive sentimentality typified by the Victorians overwhelms British life, and traditional English callousness, class warfare and lack of charity are temporarily forgotten. For it is Christmas, a time of bonhomie which, like a snowman, melts when the weather changes. For his recent works, Collishaw has drawn on two models, both making comment on the fate of the poor in contemporary London. Firstly, he has researched and updated the principles of Victorian optical toys - the zoetrope, the praxinoscope, the zoopraxiscope - to make large-scale Christmas equivalents. Secondly, he has filmed snowdomes, those small, cheap, clear plastic domes full of liquid, containing Christmas tableaux. Inside the glass bubble, filled with alcohol - 'To keep out the cold', he explains unhelpfully - artificial snow swirls while sentimental vignettes of the poor are projected. In true Disney fashion, tiny stars flicker and drop as a soundtrack plays tinny accordion music of the kind Londoners hear in the streets. The buskers on the underground, filmed by Collishaw, belong to the growing ranks of Londoners who live below the poverty line. Exactly how many is impossible to tell. For figures relating to unemployment and homelessness are so manipulated by different factions, all intent on using them for their own political gain, that it is impossible to find out the truth.
Recently Collishaw has had less to do with truth than ever. Experiments with illusion led to works such as the images of flowers with fur petals: a model of decadence on the one hand, something resembling a superb fashion accessory on the other. It is something from a fairy story, the other side of the coin to the homeless and unemployed who converge on the centre of London every day. Yet, in the winter of Princess Diana, when truth is in short supply, there might be every reason to make art equate with conjuring tricks, little miracles that really do happen. In a country where the results of the National Lottery are felt to be more important than other news, it makes some kind of sense.