The west of Ireland is so mythologised that artists approach it at their peril. But the clichés are true, writes Aidan Dunne

In an essay on the work of the painter Mary Lohan, Noel Sheridan wrote that her pictures are, in artistic terms, "the full Irish breakfast". Mostly thick with pigment, richly textured, their substance palpably conveying a subject matter of vast expanses of sand, sea and sky, her paintings have an unstinting generosity of vision about them. In that sense the current show at the Royal Hibernian Academy Gallagher Gallery, The West as Metaphor, is a full Irish breakfast of an exhibition.

It's unfashionably dense, for one thing. At a time when paintings are routinely allocated an entire wall apiece by curators, the Gallagher is brazenly packed with an extraordinary amount of work. Then there is the very premise of the show.

The west of Ireland is so mythologised, so laden with preconceptions, so invested with iconic significance, that Irish artists approach it at their peril. Whether you like it or not, it comes complete with a clutch of defining legacies: of the Gaelic Revivalists Synge and WB Yeats, of the nation-builders Keating and Lamb, the image moulders Henry and McGonigal, or the escapists Craig and McKelvey, together with a more recent scepticism about the then Bord Fáilte's projection of an unspoilt Ireland, the realm of The Quiet Man, at some removes from bungalow blight and rural depopulation.

Yet like the full Irish breakfast in an era of muesli and black coffee, the west seems to be irresistible. To judge by the work on view in the Gallagher, Irish artists appraise the stereotypes ranged against them, glance nervously over their shoulders, then can't help but have a go anyway. The exhibition begins at the beginning, incorporating the constitutive work of Paul Henry, Sean Keating et al, the work that ensures that when you approach the west as an artistic theme, you take on the very soul of Ireland itself.

In the Irish psyche and indeed further afield, national identity has long been bound up with the idea of the west. The proposition is that something essentially, authentically Irish endured and pertained in the wild, untamed peasant culture beyond the Anglicised east. The need for the definition of a distinctively Irish identity on the part of the emergent nation meant that the west's practical disadvantages could be reconfigured to national advantage.

West of the west, so to speak, are the islands. Their hard physical environments, sturdy, self-reliant inhabitants and distinctive traditions identified them as locations of cultural purity, and appropriate symbols of the island nation as a whole.

Island culture was romanticised to varying degrees, from Jack B Yeats' stalwart Man from Aranmore to Keating's more theatrical figures, peasants and fisher-folk from central casting, presented as if lit by a Hollywood lighting cameraman and painted in early Technicolor.

The idealisation of island life is at its most extreme in the myth of Hy Brazil, visualised by Jack B Yeats as a perfect venue for the races and communal events he loved, and by Patrick Collins as a remote, unattainable Eden, wreathed in Celtic mist.

For us as viewers, The West as Metaphor could be construed as a guilty pleasure. Is there a more facile stereotype not only of the west but of Irish art itself than one of Henry's generic landscapes, complete with whitewashed thatched cottage, winding boreen, turf stack and bog pool, all set against faraway blue mountains? Hackneyed views of the west are something art lovers grow out of at an early age. And yet . . .

And yet, they never quite do. Partly because of something once pointed out by painter Dermot Seymour, someone well known for his hard-headed view of the realities of rural life. When he first began to live in Co Mayo, he remarked that he had gained a renewed appreciation for Henry, because the world he looked at every day is actually like that, beautiful, just as Henry painted it. And to read Henry's own account of his enraptured discovery of Achill and its people, a life-changing experience that woke him up and brought him to his senses, is to get an intimation of the power of the place, one that will strike a chord with many.

Henry's best paintings are terrific, and they are a truthful account of what he saw. Equally truthful, though rather different in form and feeling, are Martin Gale's pictures from North Mayo. They always incorporate the practical day-to-day realities of the people who live in landscapes that are, for others, mostly and perhaps safely remote and symbolic. Caroline McCarthy has something to say about this, as well, in her well-known video piece in which she jumps sporadically into view against a typical postcard view of Irish landscape.

The persistence of a vein of romanticism in Irish landscape painting troubles some commentators. In her extensive and informative catalogue text, Dr Yvonne Scott notes Luke Gibbons' allusions to "the seductive danger of the pastoral image," and David Brett's view that artists dealing with landscape should do so critically, within the context of "themes of Ownership, Labour and Awe". Yet as Scott observes early on, the striking thing about the west in Irish art is that, by virtue of the imposing character of its physical fabric, it is representative of nature, while simultaneously being bound up with questions of culture because of its implication in Irish identity. Part of its fascination for us presumably relates to this duality.

Certainly it turns up again and again in the work included in the show, the vast majority of which is indeed critically engaged.

One particularly striking exhibit is Michael Craig-Martin's remarkable 16mm black-and-white film made in Connemara in the early 1960s, previously screened as part of his solo show at the Douglas Hyde Gallery. There is a subtle progression in its sequence of static views of classic Connemara terrain. A bleakly beautiful landscape punctuated by the occasional abandoned dwelling is gradually revealed to harbour signs of life and community.

Resurgence is hinted at. Already it belongs to another era in the history of the west. What is more surprising, though, is that the west has proved to be such a vital and enduring source of inspiration in so much Irish art made since.

The West as Metaphor is at the Royal Hibernian Academy Gallagher Gallery until Apr 24. A companion exhibition, dealing with the West in terms of its ecology and environment, follows next year