Such radicalism is one half of the French personality. The conservative France is most apparent in its sentimental attachment to a countryside full of vicious and backward peasants, subsidised by the rest of us in Europe so that they can continue to persecute hunchbacks, grow substandard apples and collaborate with the Germans. There is presumably a French TV show called Peasants From Hell, featuring these Jean de Florette monsters.
But in the town and city, the natives have always had a disposition for big, revolutionary change. Had you been born in the Marais in 1785, and lived to the age of 80, you would have witnessed five full-blown revolutions with barricades, guns, cannon, firing squads and everything.
Nevertheless, Tuesday's ban, entitled en ville sans ma voiture, was an extraordinary piece of bravery. Paris, as we know, is no city for blind men - the pavements are reserved for sidewalk cafes and parked cars. So every Parisian has a voiture. A rather chic acquaintance of mine rented a bijou apartment on the Ile Saint something-or-other, within easy swanning distance of all the sights and sounds - and yet she still insisted on purchasing a weeny, Kate Moss-style motor in that autumn's colours.
To the French, cars are sexy. That archetypical Parisienne, Nicole, drives a little red, pert Renault, the name of which - Clio - sounds suspiciously like an assertion of female sexuality. (It is marketed currently "because size matters". If the Austin were still in existence, then its next model would certainly be the Viagra, and we can confidently anticipate millennial cars with titles like the Ford Orgasm and the Chrysler Climax.) No car, no cigar.
And yet, encouragingly, radicalism won out over even the most entrenched prejudices and desires. En ville sans ma voiture was a great success, and may well be repeated. And it makes one wonder if the same trick could not be pulled in other countries. In cautious Britain, for instance, we could try a subversive, back door approach, perhaps by declaring next March 1st as Take Your Daughter To Work (On Foot) Day. Or holding a series of dress rehearsals for the Queen Mother's funeral in central London.
But what about some place where the car is really killing them? Like LA. Let us try to imagine a Los Angeles with empty freeways and deserted parking lots. It would resemble a set from one of those fashionable post- Armageddon movies, in which the only living things would be mad post-industrial killer skateboarders - and, of course, Kevin Costner plus obligatory child in need of saving. With the help of counselling, people might even walk.
Nor does such radical thinking have to stop at motor cars; there are other forms of debilitating dependency that should be tackled. The Big Apple, for instance could declare an en ville sans therapie month in which New Yorkers were not permitted to contact their shrinks. What's that? I'm terribly sorry, I've just been told that there already is such a month, and it's called August.
Closer to home (in the home, actually), we could have weeks called chez moi sans chagrin in which you are not permitted to raise your voice at your spouse, nor to be sarcastic, and in which all family conflict is settled with the assistance of an Internet link with Mr Straw's new Family Institute. Radical, but no more radical than banning cars from Paris.
And finally, I am endebted to the TV show, Seinfeld for the ultimate challenge. In one of its most famous editions, the US sitcom had its four characters - all Jewish New Yorkers - wager which of them could go longest without becoming what Bill Clinton might call auto-deponents. (This is where your hand has sex with you, but you don't have sex with your hands.)
Since it is almost certain that, one day soon, we will discover that the Victorians were right to warn of the medical dangers of self-abuse, and that masturbation causes cancer in terrapins, it may be time to plan ahead. How about (and forgive my limited acquaintance with technical French) en couche avec handcuffs?