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” and Carmen Reinhart and Kenneth Rogoff on the dangerous debt “threshold” at 90 percent of G.D.P. — faced withering criticism almost as soon as they came out.

And the studies did not hold up under scrutiny. By late 2010, the International Monetary Fund had reworked Alesina-Ardagna with better data and reversed their findings, while many economists raised fundamental questions about Reinhart-Rogoff long before we knew about the famous Excel error. Meanwhile, real-world events — stagnation in Ireland, the original poster child for austerity, falling interest rates in the United States, which was supposed to be facing an imminent fiscal crisis — quickly made nonsense of austerian predictions.