The defiantly Dionysiac qualities of Shakespeare's Falstaff would make him a nightmare figure for any modern politician. Grotesquely overweight, giddily promiscuous and terminally lawless, he would be a target for everything from anti-obesity campaigns to antisocial behaviour orders. Even his friends deride him for being "fat-witted with drinking of old sack [sweet white wine], and unbuttoning thee after supper, and sleeping upon benches after noon". He's no good in battle, he corrupts the young and he is a callous scoundrel in his dealings with women. So what is it about this flamboyant dipsomaniac that makes generation after generation take him to their hearts?
It's a question politicians might do well to ponder as they assess the results of their election campaigns. The press day for the National Theatre's Henry IV Parts 1 and 2 was the night before the general election, and the moment Michael Gambon's Falstaff appeared, a clownish anarchy prevailed that speedily subverted the high drama of the war debates in the opening scene. Physically, Falstaff is a dissolute old goat, but as soon as he opens his mouth, he takes his audience on an astonishing linguistic journey. With a barrage of puns, obscene innuendoes, deliberate misquotations and elaborate lies, he manages to ask profound questions not only about the nature of authority, but also about the qualities underpinning any decent, functioning human democracy.
In his book Shakespeare: the invention of the human, Harold Bloom ranks Falstaff as second only to Hamlet among the Bard's greatest characters. He declares that those who dismiss him as an immoral lord of misrule are "in love with time, death, the state and the censor". Certainly, it is easy to see why the censor would be dismayed by Falstaff, as he casually takes words spoken by figures of authority and - with a Rabelaisian flourish - gives them an irreverent new meaning. "Your means are very slender and your waste is great," storms the Lord Chief Justice in Henry IV Part 2. "I would my means were greater and my waist slenderer," puns Falstaff in return, effortlessly downgrading the conversation from issues of morality to more anatomical concerns.
The exchange is a very simple example of how Falstaff reveals words to be slippery as eels. Although an old dog, he has no need, with his dazzling armoury of allusions and double meanings, to learn new tricks. That ability to take the words of others and frame them in a more ridiculous light is a very useful political weapon, as this past general election campaign has shown. "Are you thinking what we're thinking?" may have seemed like a stroke of genius to the Conservatives when they made it their election slogan, but the open-endedness of its meaning allowed graffiti artists and satirists to go wild. Three weeks ago, the NS reported that kids in Leeds had graffitied "The conservatives are shit" as a riposte. Meanwhile, on Have I Got News For You (BBC2), Ian Hislop pointed out that the slogan was identical to a phrase from the children's programme Bananas in Pyjamas - provoking much hilarity and the inevitable response that "you'd have to be bananas to vote Tory".
The problem with words, as the old joke goes, is that you never know whose mouth they've been in. And as Michael Howard watched the Conservatives going down in the polls - "Are you sinking like we're sinking?" - maybe he should have reflected that if only he had paid more attention to Falstaff, he would never have picked a phrase so woefully open to reinterpretation. The Labour Party didn't escape attacks on the slogan "Britain, forward not back" - a Newsnight report quipped that with mishaps such as Sharron Storer's NHS protest during the 2001 election campaign, no wonder Tony Blair is happier to look forward. But Labour played its own distinctly Falstaffian trick in the election broadcast where the party set negative images from Howard's political career to Gladys Knight's lovingly crooned "The Way We Were", transforming the song's lyrics from an elegiac lament into a brutally sarcastic attack.
Yet Falstaff would not be ranked as one of Shakespeare's greatest creations if his main achievement was to play with words. He is important because his life of sex, sack and satire embodies the spirit of carnival identified by the Russian theorist Mikhail Bakhtin at the start of the 20th century. Bakhtin was fascinated by the long European tradition of the Festival of Fools, where for one day society would be turned upside down, as aristocrats swapped places with their servants and sacred texts were reread and given new, obscene meanings. He believed that, through these subversive games with status and language, important revelations could be made about society, which would give clues to how it might function better once order was restored.
Falstaff's relationship with Prince Hal - with all its whoring, drunken escapades and elaborately irreverent games - is ultimately a valuable education for the prince in how to negotiate life as a leader. While his father, Henry IV, deals with the murderous rebellions that are causing social upheaval, Hal is given a more gentle lesson in the breakdown of hierarchies. His father's main opponent, Hotspur, revels in grand declarations about honour and revenge, but through flippant exchanges with Falstaff, Hal learns to examine such concepts from all angles. All their conversations are verbal jousting sessions - with more virtuoso turns than anything between Blair and Howard at the despatch box - so that while their first conversation seems to be about pickpocketing and shagging the mistress of the tavern, it simultaneously satirises Puritans, invokes the classics and debates the powers of kingship.
As in the modern political world, verbal dexterity is an essential quality of leadership, but Falstaff reveals, most importantly, that even noble words are of no use if they are not backed up with action. In Henry IV, the word "honour" is repeatedly used by all of those seeking power, yet in Falstaff's most famous speech he asks: "What is honour? A word. What is in that word honour? . . . Air." Although some scholars argue that this shows Falstaff as the antithesis of honour, its point is far more profound. Just as today's electorate has needed to question what politicians mean when they use terms such as "trust" and "better future", so Falstaff shows that even when the rhetoric is high-minded, it is not always a force for good.
Never was Falstaff's influence more needed than during this past election - where, it could be argued, rarely did words mean less. Clumsily shoving their broken promises under the carpet, politicians piled on new pledges that few people believed in any more. Prince Hal may, in the end, have rejected Falstaff, but he was deeply enriched by his humanely satirical view of the world. If British democracy is to become better than some cynical charade, our politicians, too, should heed the old goat and fill their words with more than air.
Henry IV Part 1 and Henry IV Part 2 are in repertory at the National Theatre, South Bank, London SE1 (020 7452 3000) until 31 August