Noah Smith has an interesting piece in Bloomberg View: Big Economic Discovery! Booms Might Cause Busts:

Paul Beaudry and Franck Portier are two such researchers. They are famous for a 2006 theory saying that news about future changes in productivity could be what cause recessions and booms. That model never really caught on — it always had some issues with the data, and it definitely didn’t seem to be able to explain the Great Recession. But it inspired further research, and it was an interesting and novel idea. Now, Beaudry and Portier, along with co-author Dana Galizia, are going after bigger fish. They want to resurrect the idea that booms cause recessions. In a new paper called “Reviving the Limit Cycle View of Macroeconomic Fluctuations,” Beaudry and Portier try to think of reasons why booms might cause busts. The mechanism they come up with is pretty simple. You have a whole bunch of people — basically, companies — who invest in their businesses. The amount other people invest affects the amount I want to invest, but I can only adjust my investment slowly. When you have feedback effects like this, you’re going to get instability in your model economy, and that’s exactly what the authors find — the economy experiences booms and busts in a chaotic, unstable way. To reproduce the randomness found in the real economy, the authors simply add in some random “shocks” to productivity .

BP&G´s latest seem to be a variant of RBCT, where the “trend is the cycle”, or where growth and fluctuations are one and the same.

Alternatively:

“For the past half-century, the academic macro story has gone something like this: There is a general trend of rising growth and prosperity in the U.S. economy, caused by steady improvements in technology. But this steady course is disturbed by unpredictable events — “shocks” — that temporarily slow growth or speed it up. The shocks might last for a while, but a positive shock today doesn’t mean a negative shock tomorrow. Recessions and booms are like rainy days and sunny days — when you look back on them, it looks like they alternate, but really, they’re just random.”

I find the fact that economists tend to move away from monetary explanations of cyclical fluctuations hard to explain .In a recent paper by Roger Backhouse and Boianovsky – “Secular Stagnation: the History of a Macroeconomic Heresy” – we read on page 5 that:

The economist who introduced this idea into economic theory was Alvin Harvey Hansen. Born in 1887 in rural South Dakota to immigrants from Denmark, he came from the frontier that according to Jackson was ending. After majoring in English, he moved to the University of Wisconsin to study economics and sociology, before moving to Brown and writing a thesis on business cycle theory, in which he became a specialist. His early work, Cycles of Prosperity and Depression (1921) was empirical. Believing the British economist, John A. Hobson, to have rebutted the charge that under-consumption was impossible, Hansen explained cycles of prosperity and depression as the result of changes in money and credit.

However, on the next page we read:

During the 1920s, turning to the ideas of Albert Aftalion, Arthur Spiethoff and other continental European writers, he began to see fluctuations in investment, driven by population changes and waves of innovations, as the root cause of the cycle. He still thought monetary factors played a role, but they merely served to magnify other forces rather than being an independent factor.

Recently, Brad DeLong went “ballistic” in his critique of Friedman´s monetary view of the Great Depression:

These questions can be debated. But it is fairly clear that even in the 1970s there was not enough empirical evidence in support of Friedman’s ideas to justify their growing dominance. And, indeed, there can be no denying the fact that Friedman’s cure proved to be an inadequate response to the Great Recession – strongly suggesting that it would have fallen similarly short had it been tried during the Great Depression. The dominance of Friedman’s ideas at the beginning of the Great Recession has less to do with the evidence supporting them than with the fact that the science of economics is all too often tainted by politics. In this case, the contamination was so bad that policymakers were unwilling to go beyond Friedman and apply Keynesian and Minskyite policies on a large enough scale to address the problems that the Great Recession presented. Admitting that the monetarist cure was inadequate would have required mainstream economists to swim against the neoliberal currents of our age. It would have required acknowledging that the causes of the Great Depression ran much deeper than a technocratic failure to manage the money supply properly. And doing that would have been tantamount to admitting the merits of social democracy and recognizing that the failure of markets can sometimes be a greater danger than the inefficiency of governments.

I find those arguments untenable. The Great Depression only ended when FDR intervened by delinking from gold. Nominal spending (NGDP) immediately turned around (the follow-up government intervention – NIRA – only retarded the process).

The “Great Recession” only bottomed-out when the Fed adopted QE1, and subsequent doses of QE have managed only to keep the economy humming along a depressed path. A target level for spending (or even prices) would have been a better monetary solution.

The spending target level path is ancient. In the Backhouse paper I found out that Evsey Domar, before Clark Warburton, Leland Yeager, James Meade, Bennett McCallum, Mankiw & Hall, among others, had already “been there”:

“Capital expansion, rate of growth and employment” (Domar 1946). This focused on the relationship between productive capacity and national income. Investment was related to both of these, for it generated aggregate demand, which determined income, and it added to productive capacity. Because investment was linked to the growth rate of productive capacity and the level of income, Domar could show that there was an equilibrium rate of growth, at which income would grow at the same rate as productive capacity. Secular stagnation was what happened when investment grew more slowly than this, for in that case there would be an increase in unused capacity and unemployment. However, if, somehow, the growth rate of income could be guaranteed, the result would be sufficient investment to achieve growth without resorting to a government deficit.