Witness

Documentary is such a forthright, purposive, crusading kind of art form that it makes a very good job of disguising the fact that it's in decline. Photojournalism, to take just one instance of the embattled form, has, since the 1970s, been gradually ousted from its old roosting perch in the Sunday supplements to make way for lifestyle, and has retreated to the art galleries. Not so long ago it even seemed as though it was going to be drummed out of those as well.

It was symptomatic of this sorry state of affairs that 'Witness' - subtitled 'Contemporary Artists Document Our Time' - opened at the same time as the Barbican's retrospective of Sebastião Salgado's searing black and white documentary photography. The two shows were presented as if they were similar: 'Witness', which was curated by Mark Sladen, even invoked the model of the field photographer in its title. Yet what was most remarkable about the ten artists included in the show was the extent to which they shrank from insisting on facts in the way photojournalists do. These artists don't go out into the field of battle themselves, they send others, and when those reporters come back, they're never too sure whose account to believe.

English artist Phil Collins opened the show with the film Hero (2002), a clever summation of these dilemmas, and of the kind of confusion that has characterized the wrenching ideological battles after 11 September 2001. It also implicitly questions the clear-sightedness of history's witnesses. Collins' witness is a New York journalist who was on duty that day, and who is recorded talking about the experience in a fairly straightforward interview format. However, Collins plies him with drink so that he gradually gets more and more lost in a numb fog of sentimentality. The film in fact runs backwards, so he appears to sober up as he talks.

The exhibition's pervasive uncertainty about the validity or veracity of facts was exemplified in two films by The Atlas Group. The very principle behind I Think it Would be Better if I Could Weep, by Operator #17 (Anonymous) (2000) is an evasion. Following the eccentric logic of the so-called group's declaration of authorship (in fact the group comprises just one artist, Walid Raad), the film was supposedly sent to Raad by an undercover spook who was working in a coastal resort of West Beirut, where the Lebanese security services suspected subversives of meeting. The spook was charged with the task of filming a stretch of the boardwalk, but every day at dusk he would turn his camera to record the passage of the sun. He's a romantic refusenik.

Fear of the facts, however, doesn't preclude forthright handling of subject matter, and no one is more forthright than Santiago Sierra. His work is symptomatic of the chillier, more militant turn in some recent art. Spraying of Polyurethane over 18 People, Church of San Mateo, Lucca, Italy, March 2002 (2002) certainly has a horrifyingly powerful way with metaphor: prostitutes, paid to sit on a stony floor, cover their laps in a bin bag as metal rods descend and start pumping white gunk over them. But while it may be powerful, its suggestions about the nature of prostitution are, to say the least, confused.

Sierra's tone is unusual, however, in an exhibition dominated less, as one might expect, by political postures than by the soft inclusiveness of liberal humanism. Rineke Dijkstra's moving series of portraits of a young Bosnian refugee, 'Almerisa' (1994-2002), taken over the past eight years since the girl arrived in the Netherlands, is a plea for tolerance of immigrants not on the basis of any socio-economic argument but purely by virtue of our humanity. However, in 'Witness' even those who would deny the girl are given a hearing: in Arturas Raila's fascinating dual-screen projection Under the Flag (2000) a group of hard-right Lithuanian nationalists deliver their commentary on footage of affluent everyday life in Austria. One minute they're spitting abuse, the next they're more or less admitting that if only they had a job and a few quid they wouldn't hate so much.

'Witness' had a very broad, internationalist, reportage outlook, which led one to accede to the show's claim to be addressing the idea of documentation; its dark, bunker-like installation also lent the impression of digging in for some sort of conflict. But identifying the enemy was difficult. What is surely required for documents to qualify as such is a certain declaration: 'This is a fact.' And, to qualify as 'social' documentary they might have to add: '... and it is unjust.' Of all the artists in 'Witness', probably only Allan Sekula's series of slides from Seattle's anti-globalization protests of 1999 seemed conventional in this respect - one could safely assume where the photographer's allegiances lie. Of the others, one sometimes wondered exactly where they stood - though there was, undeniably, a liberal-leftist slant. This is less a problem of the show - which was valuable and arresting - than it is a problem of the moment. 'Witness' was acutely aware of the troubled times but it looked at them broadly; maybe writing this review on what seems like the eve of a very ugly war, makes one desperate for a few certainties.