Perhaps it's cultural prejudice, but Letterkenny is not the place you'd expect to encounter artworks by kitsch-meister Jeff Koons, archetypal Young British Artist Damien Hirst or globetrotters Christo and Jeanne-Claude.

Yet Object, a group exhibition curated by John Cunningham that has just ended at Letterkenny Arts Centre, featured pieces by these and many other artists whose work can be described as challenging. More than that, each exhibit was accompanied by an explanatory label that noted who the work belongs to.

The label next to the Koons made particularly interesting reading, revealing that Puppy is one of Koons's flagrantly sentimental offerings, a winsomely cute long-haired puppy-dog china vase, stocked with a bunch of brightly coloured flowers; one of many such editioned pieces made by skilled artisans to Koons's specifications; one of the pieces that, when critics suggest he is being tongue-in-cheek or ironic, he stoutly defends with a straight face.

The beauty and the emotion, he points out, are real, people respond to them as real; who are we to say differently? There is no denying that Puppy works as a piece of art that teasingly parallels the aesthetics of kitsch and as a conceptual exercise.

It takes the language of popular ornament and uses it to question notions of taste, value and meaning.

It is exactly the sort of piece Cunningham was looking for in devising Object. The idea was to draw people to have a look at the boundaries between art and everyday life.

In fact, "boundaries" was a potential title but, Cunningham notes, "it has too many of the wrong connotations, of barriers, walls, even of a kind of pseudo-scientific approach ... not areas I wanted to get involved in".

What he did want to get involved in was making people look at the question of "what makes one thing art and another not". Marcel Duchamp's answer to this question was that something is art if he - or any other artist - says so.

Hence, perhaps, the presence of Padraig Timoney's fire extinguisher in a glass case, under the title Bad Reputations Start Fires. People have, not unreasonably, been known to look at fire extinguishers in contemporary art galleries and wonder whether they are exhibits or fire extinguishers, art or everyday object.

Timoney's fire extinguisher is elevated - or reduced - to art. "Perhaps part of that," Cunningham observes, "is that it becomes useless, it loses its function." It loses and, arguably, gains by being released into additional layers of potential meaning.

This is something that was enacted repeatedly in other works in the show. Darren Lago's This Is Not A Pipe is a curious take on Magritte's celebrated drawing of the same name, in which a hairdryer is recreated as a briar pipe.

Yoko Ono's All White Chess Set - geddit? - is perhaps a bit facile. Irma-Jane Caggiano's Domestic Icons are a pair of ordinary vacuum cleaners that have been customised so that they are, incongruously, like cherished personal possessions.

Other kinds of transformation are effected in Alice Maher's Bee Dress and Nettle Jacket,both of which featured, in which the garments are ordinary but the materials unleash unexpected, paradoxical associations.

Equally, John Kindness's Winged Sneaker links street fashion to classical myth, as, in a more ironic vein, does Andrew Kearney's Mercury's Doc, a gleaming cast Dr Martens boot with what look like cabbages for wings.

Kathy Prendergast's spool of thread is actually a reel of human hair drawn from several generations of her family.

Object was the sequel to last year's Death By Geography, which explored the relationship between art and notions of space and place - and hence people's attitudes to space and place. Cunningham is from and lives in Ardara in Donegal, which lends an authority to the way his projects were angled towards the county's exceptional position, geographically, culturally and politically.

If this sounds as if it might have been unduly polemical or didactic, it wasn't.

"I'd always conceived this second show, particularly, as being playful. I thought of the artworks as being like big toys. They had to be actual, tangible things.

"If people can see the physical reality of the work, they will have more respect for what the artist is doing."

Initially, he had two pieces in mind as anchors: a wrapped chair by Christo and Jeanne-Claude and the extraordinary Mercedes-Benz Coffin by the Ghanaian fantasy coffin maker Paa Joe, from the National Museum of Scotland collection.

Joe's improvisational skill had a counterpart in another work, Bill Woodrow's quick-witted Long Distance Information, one of a long-running, brilliant series of sculptures from the 1980s in which he cannibalised defunct consumer durables to produce virtuoso sculptures of, usually, other consumer durables.

Here, sections of the bonnet of a yellow cab are ingeniously transformed into walkie-talkies, a camera with a telephoto lens and a bullet, hinting at narrative possibilities of intrigue and espionage.

The comments book of Object made interesting reading. There was the inevitable, although slight, sprinkling of annoyed incomprehension, but overwhelmingly the tone was positive.

And it is good to note that, in this august company, it was an Irish artist, Alice Maher, who struck a chord with the audience. Time and again, visitors were intrigued by the strange, contradictory ideas generated by her impossible garments.

Cunningham says he was not surprised. "They are works that speak directly to a rural audience." It was this level of rapport that made the bold experiment represented by Object and Death By Geography such a success.