Speaking in tongues: Robert Hanks finds David Edgar revising his opinions on audiences (they're dumb) and culture (it's OK by him)

Perhaps it is the glass of wine that David Edgar has awarded himself for lunch, in celebration of the fact that rehearsals for his latest play are nearly over and all he has to do this afternoon is offer a bit of moral support to the RSC's actors; but he is disarmingly frank about the people he's writing for.

'The audience is getting duller and more stupid. People who clearly watch in numbers of millions pieces of film and television that are, whatever you think of them, immensely sophisticated in their plotting, and in the devices they employ, and the length of time before they make themselves clear - people who can deal with this somehow hand their brains in when they go into the theatre.'

These are not, it's worth pointing out, the words of an embittered, failed playwright: in a playwriting career spanning over 20 years and 40 plays, Edgar has had at least his fair share of critical acclaim (for political dramas such as Destiny, Maydays and The Shape of the Table), and huge popular success (through his adaptation of Nicholas Nickleby, a hit on both sides of the Atlantic). He is also director of Britain's first post-graduate course in playwriting, at Birmingham University, and a prolific commentator in the media on the state of the theatre; so he's certainly not short of work, and you could assume that he knows what he's talking about.

Given this cynicism about the potential audience for contemporary drama, it seems particularly bold to offer them a play as densely riddled with ideas as Pentecost, which opens tonight. The play is a kind of intellectual whodunnit - in this case the question is, who painted a fresco in a now-deserted church somewhere in south-eastern Europe? The answer may, possibly, transform the history of Western art; but the painting also serves as the catalyst for a series of debates, on the West's attitude to the East, and on the relationship between art and national identity. For the citizens of this unnamed state, on 'the battlements of Europe', the painting offers proof that they are part of the bigger story of European culture, not just a marginal note.

'It's the first piece I've written,' Edgar begins, 'which starts from a cultural rather than a specifically political starting-point, which reflects a change in the way I'm thinking about the world.' The shift in perspective can be seen if you compare Pentecost with his 1990 play The Shape of the Table - indeed, Edgar specifically invites the comparison.

Both plays are deliberately topical responses to events in Eastern Europe, in Edgar's view 'where the action is' - 'I've been looking at that part of the world because it contains the history of the 20th century in a peculiarly intense form.' The Shape of the Table, premiered a year after the Berlin Wall came down, showed the collapse of Communism in an unnamed Eastern European country (plainly nearer to Czechoslovakia than anywhere else). Unsurprisingly, it was a far more optimistic play than Pentecost - violence and the fragmentation of nations have seen to that. But the real difference is that The Shape of the Table was engrossed in the nitty-gritty of politics, taking the audience behind the scenes to watch the negotiations and manoeuvring necessary before a totalitarian regime could relinquish power.

Edgar says that, 'I come from a political tradition which was always a bit suspicious about culture, as being somehow a deviation from the important business of hard politics, which as we know are a reflection of hard economics.' (He sits, in point of fact, well to the left of conventional British politics, at 'the moment where libertarianism and Trotskyism overlap on a Venn diagram'.) Two things have pushed him away from that tradition.

One is the failure of Communism in Eastern Europe (as he confesses, 'Anybody who used to call themselves a Marxist now has fairly intense self-definitional problems'); the other is the 'hijacking' of that tradition by the Right - 'the Thatcherites who now believe that everything's a reflection of the fundamental economic realities of the market'. Having been forced off their old ground, 'the Left has been able to move on to a much more rich and complicated view of the world, in which cultural questions are more important.'

To be fair, the political analysis in Edgar's most directly political stage-work has never been simplistic. A notable feature of his plays is the way that he extends imaginative sympathy to characters who are his ideological opposites - in Destiny (1976), about the rise of the extreme Right in Britain, an inarticulate National Front candidate emerges as a figure of pathos and some dignity. In person, too, the urbane and jolly Edgar hardly comes across as a doctrinaire Spart character, spinning off into eloquent digressions on the significance of the magic forest in Shakespeare.

Nevertheless, you can take his point that in its awareness of the cultural importance of art, Pentecost is a departure from previous practice. It's also a departure for Edgar in its concentration on language: something you might gather from the title, taken from the occasion when the apostles began speaking in tongues. (As it happens, the starting-point for this play was a pun on the word 'restoration' in its political and artistic senses, and Restoration would have been the title if Edward Bond hadn't got there first.) Pentecost is largely written not in English but in the closely related tongue, English as a Second Language - according to Edgar, 'now the most spoken language in the world'. He says he sees this conversation in an imperfectly shared tongue as a powerful metaphor for the way that culture develops.

It's plain that Pentecost has more themes than you can shake a stick at; and plain too that it relies largely on the audience's willingness to follow an argument. The danger is that it will end up an unwieldy Shavian talk-piece.

Edgar acknowledges that 'GBS hangs over us all, as a model and as an awful warning.'

One way in which he hopes to counter the threat of dullness is a startling switch in the play's direction (which he is anxious shouldn't be revealed).

But he also takes the view that argument is a natural part of theatre: 'We seem to have got desperately narrowed into the domestic and the familiar, and indeed into the romantic . . . the notion of the debate-play as being a play that somehow is incomplete or insufficient seems to me to be wrong.'

On the page, at any rate, the debates and the interweaving of themes in Pentecost are compelling; whether it works on stage will be revealed tonight. At any rate, patrons are advised to keep their brains with them at all times.

'Pentecost' opens tonight at the Other Place, Stratford-upon- Avon. Details below (Photograph omitted)