Officials from the so-called troika of foreign lenders to Greece — the European Central Bank, European Union and International Monetary Fund — have come to believe that the country has neither the ability nor the will to carry out the broad economic reforms it has promised in exchange for aid, people familiar with the talks say, and they say they are even prepared to withhold the next installment of aid in March…

The markets have taken into account a voluntary default by Greece, most experts say. But financial experts fear the possibility of an “involuntary” default if the negotiators are unable to reach an agreement. That could unleash violent market reactions that could conceivably produce another market cataclysm like the 2008 bankruptcy of Lehman Brothers and throw the world into another recession…

But, amid a stream of gloomy news from Europe, including the downgrade of the debt of France and eight other countries, the sense that default is inevitable is growing. “When you simply go over the bare figures I can’t really imagine another scenario,” said Michael Fuchs, a leading member of Chancellor Angela Merkel’s Christian Democratic Union in the German Parliament.

“Mathematics is mathematics, and one plus one has to equal two and not five,” he said, describing how, even with a significant restructuring of its debt, the Greek government’s deficit would still be too large and its economy not competitive enough to put the country back on a sound footing.