The challenge is particularly daunting in France, which has done less to reduce the state’s obligations than some of its neighbors. In Sweden and Switzerland, 7 of 10 people work past 50. In France, only half do. The legal retirement age in France is 60, while Germany recently raised it to 67 for those born after 1963.

With the retirement of the baby boomers, the number of pensioners will rise 47 percent in France between now and 2050, while the number under 60 will remain stagnant. The French call it “du baby boom au papy boom,” and the costs, if unchanged, are unsustainable. The French state pension system today is running a deficit of 11 billion euros, or about $13.8 billion; by 2050, it will be 103 billion euros, or $129.5 billion, about 2.6 percent of projected economic output.

President Nicolas Sarkozy has vowed to pass major pension reform this year. There have been two contentious overhauls, in 2003 and 2008; the government, afraid to lower pensions, wants to increase taxes on high salaries and increase the years of work.

But the unions are unhappy, and the Socialist Party opposes raising the retirement age. Polls show that while most French see a pension overhaul as necessary, up to 60 percent say working past 60 is not the answer.

Jean-François Copé, the parliamentary leader for Mr. Sarkozy’s center-right party, says that change is painful, but necessary. “The point is to preserve our model and keep it,” he said. “We need to get rid of bad habits. The Germans did it, and we can do the same.”

More broadly, many across Europe say the Continent will have to adapt to fiscal and demographic change, because social peace depends on it. “Europe won’t work without that,” said Joschka Fischer, the former German foreign minister, referring to the state’s protective role. “In Europe we have nationalism and racism in a politicized manner, and those parties would have exploited grievances if not for our welfare state,” he said. “It’s a matter of national security, of our democracy.”

France will ultimately have to follow Sweden and Germany in raising the pension age, he argues. “This will have to be harmonized, Europeanized, or it won’t work — you can’t have a pension at 67 here and 55 in Greece,” Mr. Fischer said.