Reviewing Reading Modern Poetry in the Times Literary Supplement in 1989, Terry Eagleton declared that the author was not of these Islands and could therefore not properly get a grip on crucial features of English poetry. The author was - Mexican. At the time this struck the author, myself, as gratuitous, nationalistic. I remembered how in my Marxising youth I was told by a sub-editor at Tribune, to which I then contributed, that I could never be a proper Marxist because I was middle class. Terry Eagleton's charge struck me as part of the same paradigm, as though - to use Seamus Heaney's notion, which I believe to be incorrect - English actually had 'exclusive civilities' and the exclusion which poets from Williams and Stevens and Bunting to Murray have experienced and kicked against had a basis in cultural fact and was not a crude atavism.

Being still, though naturalised British, of a Mexican persuasion, I approach a particularly steaming heap of literary invective - entitled 'Bizarro's Bounty' and published in a recent issue of Poetry Review - tentatively, like a protagonist in Jurassic Park approaching a large, ripe pile of dinosaur dung. The review, attacking Keith Tuma's Anthology of Twentieth Century British and Irish Poetry (Oxford New York), is subtitled 'Sean O'Brien Detects Cultural Imperialism In A New Anthology'. We may detect - those of us from post-colonial nations like the United States, Mexico, Wales, Scotland, Ireland and England - a pot and a kettle.

Tuma's provocative and intelligent anthology is reviewed in this PN Review. My purpose here is to consider features of O'Brien's polemic which - taken with other recent vitriolic misreadings by critics of O'Brien's circle - suggest that into the bland and undefended (indefensible?) culture of reception for contemporary poetry a new brutalism has entered. It is not the principled, Grigsonian vehemence of the 1940s or withering Wintersian acerbity. It is not informed by a coherent politics, despite its triumphalism; it is visceral, wilful, self-serving. Factual accuracy and intellectual precision are swept away in a torrent of - is it Stalinist, to use an O'Brien pot and kettle word, or Mosleyite? - abuse.

It is worth prefacing these remarks by stressing that Tuma's anthology is designed for an American readership, is introductory, and as a result is required to impart, in abbreviated form, as much information as it can to contextualise the verse it is presenting.

O'Brien begins, obliquely, by accusing Tuma of zealotry. This is the same O'Brien who in his Picador anthology The Firebox declared that the 'best' contemporary poetry 'displays a vigour verging on ferocity. It recreates and renews itself, replenishing the fire which by tradition Prometheus stole from the gods - the fire of creation, understanding and language.' The words 'vigour' and 'ferocity', the reaching out for a heroic allusion, the afflatus: the language of zealotry, a Paisleyite sleight away from argument, into the rhythms of rhetorical persuasion. If one pauses to interrogate the language, one discovers that it is, strictly, meaningless. Which is not to say that it is empty of vigour or ferocity.

We move in the review from zealotry to cultural imperialism, i.e. American imperialism, by way of a glancing allusion to Vietnam and Native Americans (there are maybe other, larger, previous, more brutal and successful imperialisms?). Well, within eight lines he has the bone between his teeth: 'It was once said that Americans found no cultural differences so complex that they couldn't be overcome by ignoring them', a view which has a racist feel even in its high-table hauteur, but with which O'Brien, while seeming to dismiss it, concurs. He continues, 'and in a minoroutpost- in-the-badlands way, Keith Tuma's clodhopping anthology is part of this enterprise'. Readers are invited to decant four or possibly five clichés, prejudices and sleights of hand in this one sentence. It is a sentence dictated not by subtlety but by the automatism of a man in the grip of metaphor. O'Brien lives, not in a minor outpost in the badlands, but in a minor suburb of Newcastle-upon-Tyne.

'Tuma wants us to know he comes in friendship,' says O'Brien. No, Tuma is not addressing 'us' but American readers, a fact O'Brien notes, but adds, 'the introduction reads as though aimed at some readers in Britain and Ireland who may take issue with its approach'. We are getting near the heart of O'Brien's polemic. Tuma is in thrall to Modernism and insists on the English and Irish contribution to it, and the continuing English and Irish engagement with it, despite what one might call the apparent main stream to which O'Brien is so turbulent a tributary.

O'Brien's assault continues for two pages: no single sentence is without rancour, none is precise in attack or generous in intent. The crucial untruth at the heart of the review is this: 'As to Modernism, it meets no significant resistance [in Britain and Ireland], though Eliot and Stevens are probably more widely admired than Pound (and anyway Modernism is as much a European as an American phenomenon, something Tuma doesn't seem to acknowledge).' O'Brien is so full of vigour that his sentence scampers away, a series of tangents. Quite apart from the fact that Anglo- American and Anglo-Irish Modernisms are different in kind from mainland European Modernisms, whatever the shared grounds, the opening of O'Brien's sentence is quite simply untrue. His own critical book The Deregulated Muse demonstrates its untruth. It is one thing to have selections of Eliot, Stevens, even - even - Pound on your shelf, quite another to read them and see what they do to the Romantic and Georgian legacy, see what they do to your own habits of reading and writing.

Tuma certainly does not toe an O'Brien line. The American is culpable in attempting to remind readers of the existence of John Rodker, Nancy Cunard, Charles Madge, Clere Parsons and Nicholas Moore. And - my goodness! - he omits Tom Paulin and Douglas Dunn! Well, anthologists have some painful decisions to make.

Tuma stresses in his introduction and demonstrates in his selection that Englishness and Irishness are various and irreducible. That is one of the things his book is about. Part of O'Brien's polemic is to insist that Englishness and Irishness are various and irreducible. So there is, at one level, agreement between them, though O'Brien is unaware that he is agreeing, since he spends a paragraph berating Tuma for daring to use the sobriquets English and Irish (it is OK for O'Brien to use the sobriquet American, it goes without saying).

O'Brien just can't see beyond the awful colour of the anthologist. Tuma is so brightly, garishly, luridly - American. C'mon, Sean: we're all the same under the skin. Especially us Imperialists and ex-Imperialists. Why, we're more the same than anybody else.