Mark Bauerlein gives a favourable account of Experiments Against Reality in Partisan Review (LXIX, 1). He characterises the author, the conservative editor and critic, in these terms: 'Humanities Professors hate Roger Kimball, and why shouldn't they? Ever since the publication of Tenured Radicals ten years ago, Kimball has derided the boorish moralism and pretentious radicalism of multiculturalists, feminists, cultural-studies theorists, deconstructionists, and Marxists, as well as museum curators, educators, and a host of professional diversity-mongers.'

This kind of language excludes the possibility that moralists might, in certain cases, not be boorish. It also ignores the fact that radicals might not be pretentious; that there are arguments aesthetic as well as political for cultural tolerance, and the cause of feminism cannot be extinguished by name-calling. Even theory has its place; even collective politics. If we do not tolerate diversity and discriminate within it, what are we left with? What is the dogmatic core culture for which Kimball (and his reviewer) are willing to sacrifice diversity? Who does it belong to apart from Roger Kimball, the readers of his magazine, and his co-religionists?

But there is a problem with liberal multiculturalism which I want to address because, in recent weeks, a number of people have been tainted with a Kimballism of which I doubt any is guilty. I have learned that titles ('Professor', 'Publisher') when attached to stories relating to popular culture carry a semantic burden, in this country often pejorative. Odysseus is always 'wily' no matter how many friends he loses on his ten year journey home; and Professors of Literature are always killjoys or stick in the mud conservatives, especially when it comes to popular literature. Some radio interviewers inflect the word 'Professor' much as they do 'Thatcherite'. Had the phrase not already been deployed, one might speak of their 'boorish moralism'.

At the London Book Fair I received a phone call from Radio 4's The World Tonight. Would I come to the studio and comment on the fact that Penguin had made Linton Kwesi Johnson their first living English-language Classic. The only other living poet to achieve classic status is translated: Czeslaw Milosz.

Why had they asked me? It did not occur to me at first that they wanted a square peg to hammer into a round hole, but I soon saw that they wanted a politically incorrect quotation to enhance the adversarial spin they had already projected for the story. Unfortunately, I do not dislike Johnson's work. I have supervised essays and projects both on his performance techniques and on the nature of his audience. I feel that his inclusion in the Penguin Classics list is inappropriate, but my reasons for thinking this are to do with my respect for the Penguin list and the definition of classic it seems to embody, and with my equal respect for the medium in which Johnson works.

This is what I said in the interview. The word 'classic' has specific meanings and implications, none of them to do primarily with popularity or range of appeal. The Penguin Classics list is a genuine resources, uncompromised and hitherto quite uncompromising. It has come close to the present in the work it includes but in general it acknowledges that a classic has already endured; a text can only become classic when it is stable, that is, when the author is no longer there to alter it. A living classic is put to death: think how many schoolchildren read selections from Ted Hughes' first three books and never even realised that Crow had hopped across the laureate's page.

The reasons for Johnson's addition to the list are straightforward. The list editor, Simon Winder, believes that the most powerful original Caribbean contribution to British culture since the 1950s is in the area of performance, the rapid-fire, often political and highly rhythmic rap. It is important to acknowledge that contribution, and Linton Kwesi Johnson is among the best of those performers. His work was unaccountably, and conveniently, out of print. Penguin stepped in.

Winder is of course right. The contribution of Caribbean voices, techniques and rhythms to performance poetry as well as to popular music is obvious. Johnson's own performances are often accompanied by his backing 'band'. It is entertainment of a sharply defined, specifically political order, and is compelling to watch and hear. But is it compelling on the page?

Johnson's admirers insist that it is; that it has prosodic coherence and semantic depth but I would challenge anyone who has not heard Johnson perform in his own voice to try to read the poems aloud off the page, and to scan those which have more or less regular stress patterns. 'What, even the most recent work?' I was asked by a disbelieving Guardian interviewer. Yes, even that recent work conceived less for performance than for print. The technique is less apparent on the page than in the voice which compensates effortlessly for a missing beat, an inefficient inversion, a short or over-length line, which elides and inflects and saves us the effort of interpretation. In-print difficulty is common to much performance poetry: it is compelling on stage, on CD or video, but the silent libretto, as it were, is inert. As for semantic depth: no. There are puns, word play, clichés and reanimated clichés, postures are forcefully struck. But the language does not develop ideas (the ideas precede composition and are not always original); it is a language written for effect on an audience. When performance poetry takes wing it is because something unusual emerges in the transaction between performer and audience. The written text becomes superfluous, the words often altered in response to the specifics of a public occasion.

This work is original, powerful in performance, and it has had an impact on contemporary British musical and performance culture. These things are acknowledged. But the next step, it seems to me, works against cultural respect and genuine multiculturalism. A largely white and liberal establishment, wishing to acknowledge an unfamiliar and challenging phenomenon, 'applies familiar templates to the unfamiliar' and transposes the unfamiliar into a medium that degrades and denatures it.

Penguin has an excellent cassette and CD series: to have Johnson's poems on CD, with a booklet providing a text to follow while the disc plays, would be appropriate. Such a CD could be labelled 'classic' if the recording had been made during a successful gig, performer and audience collaborating quite as much as performer and his backing group do. But stripped of the group, the audience, with the voice silent, folded into the pages of a Penguin Classic, the work has been appropriated. Its presence in the wrong medium sells it short and blurs the meaning of the words 'literary' and 'classic': this is clearly not what the work is or aspires to be.

Multiculturalism fails when it falsifies genres. This form of institutionalised misunderstanding proceeds from a mixture of political and cultural considerations. Many editors have the courage to concede as much, though not in public. What is urgently needed, if multiculturalism is not to become a form of bland relativism, a meeting-place where positive difference is airbrushed out, where creative debate and conflict are stilled, is an ability to understand formal and generic differences and inventiveness to find the right medium for each 'manifestation'. The acknowledgement and celebration of what is new and unexpected in our culture is not served by false taxonomies. They are an aspect of that 'repressive tolerance' which those of us who were radical in the 1960s so strongly opposed. Kimballs strive to re-establish cultural security through denial, but false taxonomies are as pernicious, because they deny us the instruction, pleasure and extension that come from acknowledged and understood differences in mediums and genres.