Post-Keynesians did predict a crisis, on broadly the terms that we actually experienced. They argue that there are adverse side effects to using monetary policy to manage aggregate demand. Although in theory this might be avoidable, post-Keynesians point out that in practice monetary stabilization, even above the zero-bound, seems to engender increasing indebtedness and financial fragility, and to distort activity towards overspecialization in finance and real estate. They pay much more attention to the details of financing arrangements than the other schools, and emphasize that vertiginous collapses of aggregate demand are nearly always accompanied by malfunctions in these arrangements. Aggregate demand, post-Keynesians argue, cannot be managed without concrete attention to the operation of financial institutions and the conditions that lead to their fragility. Post-Keynesians make the deep and underappreciated point that fiscal policy, even if it is conventionally tax-financed, can deleverage the private sector and reduce financial fragility in a way that monetary operations cannot. Monetary operations, if you follow the cash flows, amount to debt finance of the private sector by the public sector. The central bank advances funds today, in exchange for diverting precommitted streams of future cash from the private sector entities to the central bank. Fiscal expansion is more like equity finance of the private sector by the public sector. Public funds are advanced, and captured by parties with weak balance sheets as well as strong. But taxes are not withdrawn on a fixed schedule. They are recouped “countercyclically”, in good times, when private sector agents are most capable of paying them without financial distress. Further, the private sector’s tax liability is distributed according to ex post cash flows realized by individuals and firms, while debt obligations are distributed according to ex ante hopes, expectations, and errors. So tax-financed fiscal policy acts as a kind of balance-sheet insurance. Both by virtue of timing and distribution, taxation is less likely than monetary-policy induced debt service to provoke disruptive insolvency in the private sector. Plus, during a depression, fiscal expansions may never need to be offset by increased taxation…Never-to-be-taxed-back fiscal expenditures, if they are not inflationary, shore up weak private-sector balance sheets without putting even a dent into the financial position of the strong. They represent a free lunch both in real and financial terms.
Here is more, and it is insightful throughout. I would add two points, both in the skeptical direction:
1. I so rarely hear the post Keynesians utter the word “Congress” in discussions such as this.
2. Fiscal policy does best when it is obvious what should be produced, and there is a political consensus to make that stick, as was the case in 1940-45 for instance.