Translation: an impossible art?

'The rules for using tu and vous in French are a minefield that is almost impossible to sweep'

When you learn French at school, two of the first words you learn are tuand vous. In English both have the same translation – "you". This may well be the first time you are made aware that a word in one language has more than one translation in another.
We are taught that tu is used when addressing one person, and vouswhen addressing more than one. Easy enough. But it's a little more complicated than that. Vous is also used when addressing one person politely. If you walk into a boulangerie and ask for some bread, you only ask "As-tu du pain?" if you want to cause offence. "Avez-vous du pain?"is the norm – the form for polite singular address.
But that's far from the whole story. In fact, the rules for using tu and vousare a minefield that is almost impossible to sweep. I should know – I've spent 40 years teaching French. There is hardly an issue more divisive, confusing and misunderstood in the whole language. The difficulty has a long history behind it and encapsulates many of the contradictions of French society.
Although many languages have different words for "you", such as German and Hindi, which have three each (duihrSie, and tutumap, respectively), the use of vous, the plural "you", for a single person was invented by the French. It didn't exist in classical Latin, where tu and voswere simply the singular and plural forms of address, and it didn't emerge all at once at the birth of old French. In the middle ages vousand tu were not as firmly fixed as they are now. In the Song of Roland, the knight Ganelon can call his comrade-in-arms vous and yet switch totu in the next sentence – to express anger, for instance. Singular vousbecame more regulated in the renaissance, and by the time of Louis XIV it was obligatory except when speaking to a person of lower social rank – master to servant, servant to maid, maid to peasant, or parent to child.
Vous was such a manifest symbol of inequality that in 1794 a revolutionary faction petitioned to have it removed from the language. It couldn't be done because there was no other word to express the real plural. But from then on, the use of vous became a political issue. It still is. In 2007 Le Figaro warned that the disappearance of vous from the speech of the younger generation could lead to the end of civilisation. (Following the revolt of 1968 young people began using tu in situations where vous was required – when talking to professors, especially. It was a consciously political language-move.)
Vous has ceased to be the rock-solid norm for singular address between equals. Tu has always been the way to speak down, starting with parents to children, but it has been gradually extended to all close relationships, up or down, and thus marks a special bond between people not related by blood. What you need to know in modern France is under what conditions you may replace vous with tu.
The schoolbook version of the rule is this: tu for mother, father, brother, sister, wife and chum, and nobody else, except when speaking to children under the age of 14 or to insult the man who has stolen your parking space. But there are reckoned to be around 20,000 families in France today where vous, not tu, is the norm for all family relationships except parent to child. These are families whose ancestry can be traced back to the monarchical past. But other young families have also sought to reinstate vous: they feel it is a way of expressing respect for each other, not a declaration of royalist sympathies. In fact, Sartre and Simone de Beauvoir always addressed each other as vous – partly because of Simone's aristocratic background, but also (as most of Sartre's fans would assert) to maintain scrupulous equality between man and woman. But the more recent reinstatement of vous for kitchen-dinner talk is the linguistic equivalent of wearing a Rolex.
The French vous/tu distinction was imported into Russian by Peter the Great, and at the time of the Russian revolution Lenin saw it as a symbol of the hierarchical past. He proposed abolishing not the polite form, but the informal one, so that everyone would be treated with audible respect. But he was outflanked by comrades who went the other way, using the tuform as code for membership of the inner circle. In Soviet Russia, sayingtu to a comrade meant: you and I belong to the party. The style was adopted by the French Communist party, and French tu likewise came to mean, we are party members. Since one of the targets of the 1968 uprising was the hidebound party itself, stealing its linguistic signature by addressing everyone as tu was a crafty way of dissolving it into irrelevance. The result was that in the 1970s French universities and schools became tu-only zones. To say vous to a student meant you were a fuddy-duddy; to insist on reciprocation turned you into a fascist.
But history has turned this on its head. Tu in place of vous now signifies the opposite of what it did 40 years ago. In hierarchical interactions – with your head of department, for example – tu makes you sound flamboyantly cool and easy-going: like as not, you're a pro-American Sarkozyste, not a superannuated soixante-huitard. It connotes openness, friendliness, informality – virtues, or vices, now associated with globalisation and the US.
Educational reformers and public worrywarts now raise the alarm that French culture is going down the drain, propelled by the abandonment of the proper use of tu and vous among children, students and chat-show hosts. Unfortunately for them, it's not easy to say what the proper use of these untranslatable terms actually is, or ever was.
The French church abandoned singular vous in 1970 – supposedly because of Vatican II in 1966, but more probably as an acknowledgment of 1968. French Catholics are now supposed to say "Notre père qui es aux cieux, que ton nom soit sanctifié" in a translation that is at last, after nearly a thousand years of divergence, in literal accordance with the Latin they were always supposed to know by heart.
If you no longer say vous in the most upwardly direction imaginable, to whom on earth do you say it? Despite spending years teaching young people how to get it right, I often get it wrong myself. It's utterly frustrating. So I'm giving up. I'll say vous and tu as I please from now on, and leave my French friends to work out if I mean anything by it, or am just an incompetent speaker of French. I've come to realise that the real utility of the ever-shifting divide between vous and tu is to keep people out. You have to be part of the game to play.
Languages can serve many purposes. French second-person pronouns and the English definite article show that one of them is to confirm membership of a group.
David Bellos's Is That a Fish in Your Ear? Translation and the Meaning of Everything is published by Particular Books.