THE PAVEMENTS of the Boulevard Saint-Michel (Boul'Miche for those who were there) are lined this week with grainy blow-up photographs showing euphoric young men in polo-necks chucking cobble-stones at police.

Bookshop windows bulge with coffee-table compendiums celebrating "les evenements", while television stations roll out classic footage of barricades, wall-slogans and an ageing Charles de Gaulle. The blond mop-head of Daniel Cohn-Bendit - one-time student leader, now ultra-respectable Green Party chief in the European parliament - grins from every news stand.

The 40th anniversary of the May 1968 student-worker "uprising" has hit France with a vengeance.

The same ritual of remembrance has been acted out before of course, but this year there is a crucial difference. For the first time, many of the accepted truths about the iconic episode are being openly challenged.

The soixante-huitards who came to cultural and institutional power in the 1970s and 1980s are now moving into retirement. It is their celebratory version of May 1968 as a liberating historical landmark that has dominated since that month.

But now a younger generation is reappraising their parents' ideological touchstone, and they do not like what they see. Far from ushering in a golden age of freedom after the crushing tedium of de Gaulle's decade in power, the events are increasingly regarded as having set in place many of the economic and social problems that have dogged France ever since.

"The 1968 generation is the me first' generation," admits Jacques Attali, 63, a former adviser to socialist president Francois Mitterrand who is now a stern critic of his own epoch.

The strongest argument directed against the 68ers - otherwise known as the nation's post-war baby-boomers - is that by enshrining a dogma of social entitlement they have led France to a financial precipice.

In 1974, the country's budget was in balance for the last time. Since then, public debt has exploded as successive governments of left and right lavished money on social protection programmes, financial bail-outs and a massive state sector. Today, France pays out £32.8 billion a year just to finance what it owes.

"Our parents' generation - who inherited a France that was ravaged by war - bequeathed to us a country that was prosperous and only slightly in the red," said Gilles Carrez, who heads the National Assembly's finance committee. "We by contrast, the spoilt baby-boomers, we leave our children a mountain of debt. A whole generation has been living beyond its means."

The recipients of 40 years of state largesse are now moving to their second homes in the countryside - where to bemoan the inevitable economic cuts and the advance of economic "liberalism" as their children shoulder the cost of what they enjoyed.

Another legacy of the May 1968 ideology is the appalling state of France's labour market - particularly for young people. A generous system of university education for practically all has led to overcrowded lecture halls and a plethora of degrees with no relevance to the real economy.

At the same time, rigid employment laws that give cradle-to-grave protection for those in work discourage companies from taking on staff. As a result, 19% of under-25s are without a job, many more are on short-term contracts or internships, and hundreds of thousands are seeking opportunities in Britain and elsewhere.

"There is a real malaise," said Arnaud Guerreiro, a 32-year-old executive whose anger with the soixante-huitards has led him to set up the internet site nousnepaieronspasvosdettes.com (which translates as "we will not pay your debts").

"Things are so blocked up here in France that some people wonder whether there is any point continuing their studies," he added.

If more people - not least President Nicolas Sarkozy himself - are these days happy to blame May 1968 for France's travails, what about the other case for the defence: that the four weeks of riots joyously exploded the po-faced conservatism of a country in moral chains? Here again, history is being re-written by critics - many on the left - who say the catalytic role of les evenements has been greatly overstated; France had already changed profoundly.

For example, the age at which women had their first sexual encounter fell dramatically in the early part of the 1960s, and has not moved significantly since. Contraception was legalised in 1967 and had been widely available well before that. "There is a real confusion between cause and effect," said Francoise Hardy, a French singing star in the 1960s.

"May 68 simply highlighted and endorsed an evolution that had started a long time before and was just coming to maturity."

Philosopher Jean-Pierre Le Goff, who himself took part in the "uprising", agreed. "Contrary to the received wisdom, May 1968 was not nearly as modernising as it seems," he said. "France in the 1960s was not at a standstill, but was heavily influenced by modernity."

For Le Goff, the soixante-huitards transformed their moment of glory into a myth, and then used their pre-eminent position in the intellectual and cultural establishment to pre-empt any reassessment. Until now, that is.