Notions with their knickers in a twist, the sine qua non for this form of farce, are in abundant supply in Kafka's Dick, the Alan Bennett comedy which opens next week in its first London revival directed by Peter Hall. It's an astutely equivocal play about the English vice of prurient literary biography ("In England, facts like that pass for culture. Gossip is the acceptable face of intellect") and about a writer's ambivalent relationship to same. Kafka is an ideal focus for this discussion, because he shrank from the intrusion of having his fiction - let alone his life - pored over by posterity. The play begins, however, with a scene that casts doubt on the sincerity with which the dying Czech author ordered his friend, Max Brod, to burn his writings.
Bennett creates an ingenious farce scenario for testing Kafka's qualms by having him and Brod materialise decades later in the suburban Leeds home of Sydney, an insurance man and confirmed Kafka buff who is writing an article about his hero for the trade journal Small Print. If Brod had kept his word, of course, Sydney's shelves would not be groaning with the products of the tireless Kafka industry (Kafka's Loneliess, the Agony of Kafka etc). Cue a scene in which Brod and Sydney desperately try to sneak away all these offending volumes behind the back of our genius, who is still supremely ignorant of his posthumous celebrity.
There's a wry twist in this, though. Farce is a form normally populated by frighteningly single minded characters. But Kafka, like the author of Kafka's Dick, is chronically in two minds about everything. So in one strand of the play, there's a calculated, drolly revealing mismatch between the genre and the leading character who is writhingly only half horrified to discover he is a literary legend. The further joke is that as well as being the figure from whom things must be hidden, he is also the figure who has something embarrassing to hide. To conceal the fact that he has a tiny penis, he will have to rewrite the biographical record and deny that his overbearing father was a big prick.
Philosophical farce works best if there's an intriguing conceptual relationship between form and content, even when, as in Kafka's Dick, it consists in a witty discrepancy. Perhaps the most devilishly clever, neo-Stoppardian marriage between these elements to date was pulled off by Terry Johnson's 1993 play Hysteria which is set in the mind of Sigmund Freud shortly before he died from cancer. The aged psychoanalyst has just, we are led to believe, been to see the famous Ben Travers farce Rookery Nook. What follows is like Rookery Nook after a severe collision with the surrealism of Salvador Dali. Indeed, the ego maniac Spanish painter arrives on the scene to discover a pressure-bandaged Freud holding a bicycle covered in snails, with a hot water bottle attached, and a naked lady in his closet. "Maestro," he proclaims, sinking to his knees in admiration, "What Dali merely dreams, you live!"
The idea that Freud went to a performance of Rookery Nook is a naughty fabrication, reinforced by a po-faced programme note that succeeded in fooling a lot of people. What is not in dispute, though, is the fact that there is a perfect metaphoric co-relation between farce and Freudian method and hence some justice in springing such a play on him. The problem with Hysteria is that it includes material too anguishing to be accommodated in this uproarious scheme - specifically the charge that Freud, for defensive and opportunistic reasons, changed his view that child abuse is a fact to the theory that it is a fantasy borne of desire. In its awkward gear changes, Hysteria demonstrates how often philosophical farce is forced to suspend farcical operations or face the charge of exuberant heartlessness.
Form and content achieve a blither, cheekier, but no less telling partnership in Blue Murder, Peter Nichols' canny farce about theatrical censorship. In the second half of this work, a dramatist arrives at the swanky St James' Palace office or the Lord Chamberlain to defend the one-act play we have just seen in the first half. The date is 1967, the year before the Lord Chamberlain and his anachronistic team of retired military men lost their power. The excellent joke is that, while the sensors sit solemnly running a blue pencil through any hint of impropriety in the script ("a stiff one" for a whisky instantly gets the chop), precisely the kind of kinkiness they would delight in removing from a play (bisexual, blackmailing guardsmen holed up in lavatories etc) is proliferating around them. Exposing this supposed bastion of respectability as a hotbed of hanky panky - the image of what it professionally abhors - is the play's adroit, self-reflexive of spurring the absurdities of censorship.
Farce is a brutally difficult form to bring off and all the harder if the frantic physical shenanigans are meant to be the reflection of an intellectual debate - a sort of No Sex Please, We're Neo-Hegelians. There have, unsurprisingly, been some dismal failures, such as The Life of the World to Come, Rod Williams' limp, untidy farce about the ethics of cryogenics suspension. And the form has even defeated dramatists whose intelligence and powers of construction would, you'd have thought, earmark them as natural.
Despite a number of rewrites, Michael Frayn has never cracked the problem of Balmoral, a farce which takes off from the reverse-image idea that the Communist Revolution of 1917 took place in England. Frayn has subsequently argued that the play, with its counter-factual world, is inherently flawed. But if that is so, it is hard to account for Kafka's Dick and Hysteria. Another reason for its comparative failure might be that the piece - in which a capitalist Russian journalist visits the State Writers' Colony at Balmoral and, through a series of farcical misunderstandings, is converted to ardent communism - never brings into sufficiently animated play the philosophical underpinnings of these opposed ways of life. There's a distinct shortage of conceptual twists.
Of course, the final twist in Kafka's Dick is that the play is comically complicit with the gossipy culture it condemns. After all, if Kafka affects to be appalled at publications like The Loneliness of Kafka and Kafka's Agony, he would surely also have a real job trying to keep his cool at a performance of Kafka's Dick.
Piccadilly Theatre, London (booking: 0171-369 1734)