Fiscal Policy Puzzles
Many macroeconomists, however, are skeptical of the Keynesian model. And even among modern Keynesians, there is disagreement about specifics. I think it is fair to say that short-run business cycle theory remains one of the least settled parts of economics. Any economist approaching the subject should bring an ample dose of humility. (The alternative is a surfeit of hubris--a character trait all too common among economic commentators.)
The Keynesian model has some clear, practical insights about how to think about fiscal policy during economic downturns. But are those insights true?
One approach to answering this question is to examine the data using the techniques of time-series econometrics without imposing much a priori theory. For monetary policy, there is a large literature that does this; for fiscal policy, the literature is smaller but growing. The results from this exercise, however, do not always confirm the predictions from textbook Keynesian models.
For example, here is the conclusion of Andrew Mountford and Harald Uhlig (a prominent econometrician now at the University of Chicago) in an empirical study called "What are the Effects of Fiscal Policy Shocks?":
Our main results are that
- a surprise deficit-financed tax cut is the best fiscal policy to stimulate the economy
- a deficit[-financed government] spending shock weakly stimulates the economy.
- government spending shocks crowd out both residential and non-residential investment without causing interest rates to rise.
An earlier, related paper by Olivier Blanchard and Roberto Perotti called "An Empirical Characterization Of The Dynamic Effects Of Changes In Government Spending And Taxes On Output" reported similar anomalous results:
we find that both increases in taxes and increases in government spending have a strong negative effect on private investment spending. This effect is consistent with a neoclassical model with distortionary taxes, but more difficult to reconcile with Keynesian theory: while agnostic about the sign, Keynesian theory predicts opposite effects of tax and spending increases on private investment. This does not appear to be the case.Blanchard, incidentally, is now the chief economist at the IMF.
I am not sure how convinced I am by these findings. And even if they are correct, I am not sure what model I should use to explain them and to what extent that model would apply to the extraordinary economic circumstances we now face. At the very least, these puzzles should give us reason to pause when using the Keynesian framework for policy analysis. There is still a lot about macroeconomics that remains deeply puzzling.