Economic debates rarely end with a T.K.O. But the great policy debate of recent years between Keynesians, who advocate sustaining and, indeed, increasing government spending in a depression, and austerians, who demand immediate spending cuts, comes close - at least in the world of ideas. At this point, the austerian position has imploded; not only have its predictions about the real world failed completely, but the academic research invoked to support that position has turned out to be riddled with errors, omissions and dubious statistics.

Yet two big questions remain. First, how did austerity doctrine become so influential in the first place? Second, will policy change at all now that crucial austerian claims have become fodder for late-night comics?

On the first question: the dominance of austerians in influential circles should disturb anyone who likes to believe that policy is based on, or even strongly influenced by, actual evidence. After all, the two main studies providing the alleged intellectual justification for austerity - Alberto Alesina and Silvia Ardagna on ‘expansionary austerity