Austerity has failed. It turned a nascent recovery into stagnation. That imposes huge and unnecessary costs, not just in the short run, but also in the long term: the costs of investments unmade, of businesses not started, of skills atrophied, and of hopes destroyed.

What is being done here in the UK and also in much of the eurozone is worse than a crime, it is a blunder. If policymakers listened to the arguments put forward by our opponents, the picture, already dark, would become still darker.

How Austerity Aborted Recovery

Austerity came to Europe in the first half of 2010, with the Greek crisis, the coalition government in the UK, and above all, in June of that year, the Toronto summit of the group of twenty leading countries. This meeting prematurely reversed the successful stimulus launched at the previous summits and declared, roundly, that “advanced economies have committed to fiscal plans that will at least halve deficits by 2013.”

This was clearly an attempt at austerity, which I define as a reduction in the structural, or cyclically adjusted, fiscal balance—i.e., the budget deficit or surplus that would exist after adjustments are made for the ups and downs of the business cycle. It was an attempt prematurely and unwisely made. The cuts in these structural deficits, a mix of tax increases and government spending cuts between 2010 and 2013, will be around 11.8 percent of potential GDP in Greece, 6.1 percent in Portugal, 3.5 percent in Spain, and 3.4 percent in Italy. One might argue that these countries have had little choice. But the UK did, yet its cut in the structural deficit over these three years will be 4.3 percent of GDP.

What was the consequence? In a word, “dire.”

In 2010, as a result of heroic interventions by the monetary and fiscal authorities, many countries hit by the crisis enjoyed surprisingly good recoveries from the “great recession” of 2008–2009. This then stopped (see figure 1). The International Monetary Fund now thinks, perhaps optimistically, that the British economy will expand by 1.8 percent between 2010 and 2013. But it expanded by 1.8 percent between 2009 and 2010 alone. The economy has now stagnated for almost three years. Even if the IMF is right about a recovery this year, it will be 2015 before the economy reaches the size it was before the crisis began.

The picture in the eurozone is worse: its economy expanded by 2 percent between 2009 and 2010. It is now forecast to expand by a mere 0.4 percent between 2010 and 2013. Austerity has put the crisis-hit countries through a wringer, with huge and ongoing recessions. Rates of unemployment are more than a quarter of the labor force in Greece and Spain (see figure 2).

When…