The Economist about Keynes, The Multiplier, IMF and Lucas

In 2013 economists at the IMF rendered their verdict on these austerity programmes: they had done far more economic damage than had been initially predicted, including by the fund itself. 

What had the IMF got wrong when it made its earlier, more sanguine forecasts? 

It had dramatically underestimated the fiscal multiplier. 

The Economist print 13 August 2016