The Romers, and I suppose other neoclassical macro economists, believe that the economy tends towards full employment equilibrium and will move there on its own without need for government intervention or stimulus. They would acknowledge that following a negative shock, government stimulus spending may accelerate the recovery somewhat, as Bernstein and Romer in 2009 anticipated the Obama stimulus would speed recovery by about 6 months. They deny, however, that stimulus spending could change the permanent level of output because the economy will on its own return to full employment at a capacity output set without regard to the level of employment by factor endowments, by preferences, and by the level of exogenous technology. From this perspective, because a period of prolonged measured slow growth cannot be caused by involuntary unemployment, it must, by a priori assumption, be due to a decline in the exogenously determined growth rate in capacity. Like mosquitos on an otherwise delightful summer afternoon, slow growth is unfortunate but there is little that can safely be done about it.Gerald Friedman responds to Christina and David Romer
Or maybe we can find safe pesticides. Here I agree with John Maynard Keynes that the economy can have a low-employment equilibrium because of a lack of effective demand, and I agree with Nicholas Kaldor and Petrus Verdoorn that productivity and the growth rate of capacity can be increased by policies that push the economy to a higher level of employment. And to the contrary, periods of prolonged unemployment and underutilization of capacity can lower capacity by discouraging workers and reducing the incentive to invest, to innovate, and to raise productivity. Unfortunately, this is what has been happening in the US for the last few years; and, fortunately, there is reason to believe following Keynes/Kaldor/Verdoorn that policy can reverse this decline by pushing the economy to a higher level of output and thus a higher level of productivity….