First, countries can’t easily escape the consequences of past mismanagement. Greece, Italy and Portugal are all projected to run what are called primary budget surpluses next year. That means that their governments will take in more money than they spend, if you don’t count interest payments. In other words, they would now be in great financial shape, thanks to all their belt-tightening, if it weren’t for the burden of the debt they accumulated in the past. By contrast, the U.S. primary deficit is still a whopping 6% of GDP, significantly higher than that of every country in the euro zone. If weak European countries have to pay off all their past debts at the same time that they are running primary budget surpluses, they will face a very long period of austerity indeed.

The second problem is that over the past decade, the euro has created a severe misalignment in labor costs (after adjustment for differences in productivity). Labor costs in weak countries are as much as 20% higher than those in Germany. Part of the reason for the gap is that those countries let wages and benefits rise too fast in past years, and another part is the result of subpar gains in productivity. There are three possible fantasy solutions: everyone could leave the euro and then rejoin it at new exchange rates that equalized costs; everyone in high-cost countries could agree to 20% wage cuts; or a massive wave of new investment could boost productivity. None of those things is particularly likely. More realistically, countries with overpriced labor have a choice between simply leaving the euro zone or preparing for years of austerity that slowly grinds down their labor costs.

The third problem is that perpetual austerity is not only intolerable, it is also ineffective. Occasional protests that result in some broken shop windows are one thing. But current demonstrations in Europe against stringent austerity policies reflect the unraveling of the social fabric itself. What is worse, there is little chance that such policies can solve Europe’s financial problems within a reasonable time frame. There is simply too much debt to pay down and too many accumulated structural problems. Moreover, if austerity pushes countries into recession, their shrinking economies will actually become less capable of hitting financial targets.