Edinburgh Festival Day 17: A game of two halves: They cost nothing. They are the size of a credit card. And they threaten to subvert the art world. Iain Gale investigates

Across Edinburgh, people are looking at works of art, engaging in a visual dialogue which taxes their faculties of appraisal and evaluation. But the focus of their attention is not the impressive collections in the city's art galleries, but 24,000 works of art which cost almost nothing and are just the size of a credit card. Despite their size and apparent lack of value, however, they constitute the most fascinating and innovative art show of the whole Festival.

'Outpost' is a revolutionary concept which aims to extend our understanding of the processes that condition the way we look at art. Originally the brainchild of Clive Sall and Emma Davis of FAT (Fashion, Architecture, Taste), the project, now supported by Independent Public Arts, is centred around 240 artists, of varying degrees of celebrity and talent, each of whom has been asked to produce 100 copies of an original work of art in two halves. One half is distributed from dispensers at sites across the city. You simply take one and make of it what you will.

This is the essence of a project whose raison d'etre is the willingness of the public to make its own critical decisions about art. You become involved the moment you take a card, effectively becoming curator, critic and collector. Once you have accumulated a few cards, preferably from different venues, the next step is to take them to the Outpost stand in the Traverse theatre foyer where, for a price which varies from 10p to pounds 10 (all proceeds go to an Edinburgh Aids charity) you can collect a 'signature' card which reveals the identity of the artist. For a further pounds 4, you can buy a catalogue which also acts as a display album. Stick in your cards and you have the exhibition.

It is simple and effective, and raises interesting questions about the way we view art. The credit- card format, for example, might alert the viewer to an intention to subvert the traditional hierarchy of dealer, artist, museum. But Sall is emphatic that he and Davis are not 'art terrorists'; 'We simply want to circumvent institutions,' he says. It's a simple thesis: art galleries, public and commercial, present works in a way which by its nature implies greatness. If it's on the wall, sanitised and sanctified, it must be good. Decontextualising begins with the venue. By locating the house-shaped dispensers not only at the National Gallery of Scotland and the Fruitmarket Gallery, but also at Burger King, Waverley station, a post office and a go-go pub, the organisers are indulging in a form of gentle subversion. In a gallery setting, the layman will suspend critical judgement to worship at the altar of high art. The first thing to do is find the name. But with Outpost, the artists' names are not revealed, along with the second half of the diptych, until the art is paid for. With no authorship evident, viewers are coerced into making the effort to regain their often neglected critical faculties.

There is much to choose from. The works of art are ingenious in their diversity, from a sculpture created from a piece of string and evidence of the recent fad for chocolate in the word piece 'lick me' through a mildly obscene fax from Germany to simple, effective abstraction. Having decided, in the crush of Burger King or the serenity of an art gallery, whether or not to keep the first card, the viewer's next decision is whether to pay the amount demanded for the second. So, after the aesthetic judgement comes that of value. A twist is that while some of the artists on show are students, others (a list is available), are known and exhibited names. Part of the interest comes from the excitement of gambling on your own taste. Once the collection is assembled, its display in the gallery of the book is at the viewer's discretion.

Via this sequence, the viewers become curators in a process which, one hopes, will teach them something that they won't find in a textbook. Of course, the pool of artists is finite and generally not traditionalist. So one could say that the organisers have already imposed their own critical criteria. Nevertheless, by the time the dispensers are empty and, with luck, all the signatures claimed, there could be some 500 more people in the city who understand what it is to be a curator or critic. If only it were really that simple.

Artworks will be dispensed until 2 Sept. An exhibition will be held of the work. Details from Independent Public Arts on 031-558 1950. An Outpost project will be part of the Venice Biennale in 1995

(Photograph omitted)