Though it was the man for all seasons, Sir Thomas More, who coined the term around 1516, the notion of Utopia, and its pendant, dystopia, are as old as the Garden of Eden and the serpent. But the 20th century, on the whole, has not been a good one for Utopian projects. From vast socialist states to idyllic Stepford suburbs, flower power to comely maidens dancing at crossroads, one by one the visions have come to grief.

So when Douglas Hyde Gallery curator John Hutchinson canvassed for artists for an exhibition called Utopia, surely he was being slightly ironic. Not so, he says. "I certainly didn't make any assumption that the artists would take a dystopian approach. It's true that the opening of the show falls between the eclipse and Friday 13th, and it's the nearest thing to a millennial exhibition that we're going to have, so we were tapping into all that to some extent. But Utopia is what I meant."

Given the century that's in it, though, it was inevitable that artists would take a dim view of Utopian prospects, and in the event there is a great deal of irony and scepticism, not to mention outright pessimism, in the work on offer. Walker & Walker, for example, take one of the key works of European Romanticism, Casper David Freidrich's Wanderer Above the Mists - in which a hiker pauses on top of the world, gazing over a sublime mountain view - and recreate it, rather in the vein of the Chapman Brothers, as a mannequin sculpture. Their wanderer mannequin looks out through a window of the Douglas Hyde into an enclosed concrete yard, the city positively crowding in. But while their intent is clearly ironic, as Hutchinson sees it, a stubborn idealism persists in the finished work. "The aspiration is still there. There's something heroic about the figure, still aspiring to sublimity despite the setting."

While he wasn't looking for cynicism, he did want "an oblique approach" and hoped to find patterns emerging "without imposing too much of my own ideas, though I suppose what I selected in the end does in some way reflect my own ideas". There are 18 artists in the show, which attracted 160 proposals. "More by chance than design, it's roughly 10 per cent of the submission," Hutchinson observes. He was hoping to come up with unfamiliar names, and feels he has done so. "The way it breaks down is that about five or six are the usual suspects, the people you'd expect to see. Another five or six were unknown to me, and the remainder you wouldn't be surprised to find applying."

Generally, the work in the show is indeed oblique in its approach to the theme. You could say that, rather than simply describing a notional Utopia, it consists of commentaries on a diversity of Utopian conceptions. Hutchinson sees it falling into the broad categories of "dreams for the future, and failed dreams, of idealised social spaces".

Brendan Grant's fallen parachutist, sprawled on the floor of the gallery, is a latter day Icarus. More's Utopia was an island, evoked in Blaise Drummond's three "island" paintings, in which isolated motifs float against flat coloured grounds. Bocklin's Island of the Dead, a big luxurious house, a swimming pool. Clare Langan's isolated house might be its own island of domesticity, but it is also unsettling rather than reassuring.

Peter Maybury and Enda Bowe refer to notions of family. Maybury's faded snapshot of a couple in a romantic setting wavers uncertainly in a tiny video monitor. Enda Bowe's colour photographs of a grandmother and grandson regard each other across a void in the building. There is a sinister note to Andrew Vickery's relentless evocation of childhood festivity: Christmas, holidays, fairgrounds, circuses, all witnessed through a toy proscenium arch and a stage set which has some dark associations in itself.

There's a bitter, gritty edge to Ronan McCrea's two photographs of exceptionally brutal urban settings, one dominated by a blank security shutter, the other by a heavy metal door, on both of which the word "sex" is scrawled. McCrea's work recalls Modernist architecture's close identification with Utopian ideals, as do Gerard Byrne's: blank, empty interiors of anonymous offices blocks, with a slightly untidy, dishevelled appearance. Orla Ryan's audio piece evokes the town-planners' Utopian tower blocks. Maurice O'Connell's Redundancy Mandala is an imaginary boardgame writ large, a kind of management guidance manual path to effecting redundancies. But, predictably enough, for true dystopian spirit look no further than Paddy Jolley's blurred photographs of something nasty in the woodshed - or rather, of strange, dummy-like bodies and funny business in a furrowed field.

There are more optimistic notes. Grace Weir's seamless 360-degree pan, which plunges us underwater and up to the skies, captures a sense of freedom and release. But it is Eva Rothschild's work that perhaps best encapsulates Hutchinson's notion of an artist alert to the flaws of a particular Utopian project but seeing beyond them to the necessity of the underlying ideal. Her black-and-white reproductions tacked casually to the wall are varieties of recurrent fantasy images: stars and planets, sci-fi worlds, symbolic abstract patterns. She describes them as images that we hardly notice because they are so much part of the scenery, tacked to walls in student flats and teenage bedrooms. They are fantasies that transcend the everyday but, she hopes to demonstrate, etched deep into our psyches, they are also real, also part of the everyday.

Utopias is at the Douglas Hyde Gallery until September 24th