What’s Real about Real Business Cycles Theory?

from Lars Syll

In the nineteenth and twentieth centuries economists usually thought they could perceive a pattern of cyclical movements in overall economic activity. These observed patterns of regularity came to be called “business cycles”.

When I began my economics studies in the 1970s a large part of the curricula were still devoted to teaching students elementa of these recurrent phases of macroeconomic processes.

Today – although we still often talk about “business cycles” – mainstream macromodels of “business cycles” do not really contain anything of what we used to mean by the unfolding of repetitive, periodic phases in the development of economies over time. Business cycles theory in academia today is rather about economic fluctuations set within microfounded macromodels where hyperrational representative actors optimize over time – and where the dividing line between more traditional growth theory and short-run economic ups and downs is more or less imperceivable

So, something rather drastic has happened on the way. I think one of the main reasons for the turn in focus and aspiration levels when it comes to business cycles theory has to do with the advent of the Real Business Cycles Theory in the 1980s. 

Real business cycles theory (RBC) basically says that economic cycles are caused by technology-induced changes in productivity. It says that employment goes up or down because people choose to work more when productivity is high and less when it’s low. This is of course nothing but pure nonsense – and how on earth those guys that promoted this theory could be awarded The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel is really beyond comprehension.

In yours truly’s History of Economic Theories (4th ed, 2007, p. 405) it was concluded that

the problem is that it has turned out to be very difficult to empirically verify the theory’s view on economic fluctuations as being effects of rational actors’ optimal intertemporal choices … Empirical studies have not been able to corroborate the assumption of the sensitivity of labour supply to changes in intertemporal relative prices. Most studies rather points to expected changes in real wages having only rather little influence on the supply of labour.

And this is what Lawrence Summers – in Some Skeptical Observations on Real Business Cycle Theory - had to say about RBC:

The increasing ascendancy of real business cycle theories of various stripes, with their common view that the economy is best modeled as a floating Walrasian equilibrium, buffeted by productivity shocks, is indicative of the depths of the divisions separating academic macroeconomists …

If these theories are correct, they imply that the macroeconomics developed in the wake of the Keynesian Revolution is well confined to the ashbin of history. And they suggest that most of the work of contemporary macroeconomists is worth little more than that of those pursuing astrological science …

The appearance of Ed Prescott’ s stimulating paper, “Theory Ahead of Business Cycle Measurement,” affords an opportunity to assess the current state of real business cycle theory and to consider its prospects as a foundation for macroeconomic analysis …

My view is that business cycle models of the type urged on us by Prescott have nothing to do with the business cycle phenomena observed in The United States or other capitalist economies …

Presoctt’s growth model is not an inconceivable representation of reality. But to claim that its prameters are securely tied down by growth and micro observations seems to me a gross overstatement. The image of a big loose tent flapping in the wind comes to mind …

In Prescott’s model, the central driving force behind cyclical fluctuations is technological shocks. The propagation mechansim is intertemporal substitution in employment. As I have argued so far, there is no independent evidence from any source for either of these phenomena …

Imagine an analyst confronting the market for ketchup. Suppose she or he decided to ignore data on the price of ketchup. This would considerably increase the analyst’s freedom in accounting for fluctuations in the quantity of ketchup purchased … It is difficult to believe that any explanation of fluctuations in ketchup sales that did not confront price data would be taken seriously, at least by hard-headed economists.

Yet Pescott offers an exercise in price-free economics … Others have confronted models like Prescott’s to data on prices with what I think can fairly be labeled dismal results. There is simply no evidence to support any of the price effects predicted by the model …

Improvement in the track record of macroeconomics will require the development of theories that can explain why exchange sometimes work and other times breaks down. Nothing could be more counterproductive in this regard than a lengthy professional detour into the analysis of stochastic Robinson Crusoes.

Thomas Sargent was awarded The Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel for 2011 for his “empirical research on cause and effect in the macroeconomy”. In an interview with Sargent in The Region (September 2010), however, one could read the following defense of “modern macro”:

Sargent: I know that I’m the one who is supposed to be answering questions, but perhaps you can tell me what popular criticisms of modern macro you have in mind.

Rolnick: OK, here goes. Examples of such criticisms are that modern macroeconomics makes too much use of sophisticated mathematics to model people and markets; that it incorrectly relies on the assumption that asset markets are efficient in the sense that asset prices aggregate information of all individuals; that the faith in good outcomes always emerging from competitive markets is misplaced; that the assumption of “rational expectations” is wrongheaded because it attributes too much knowledge and forecasting ability to people; that the modern macro mainstay “real business cycle model” is deficient because it ignores so many frictions and imperfections and is useless as a guide to policy for dealing with financial crises; that modern macroeconomics has either assumed away or shortchanged the analysis of unemployment; that the recent financial crisis took modern macro by surprise; and that macroeconomics should be based less on formal decision theory and more on the findings of “behavioral economics.” Shouldn’t these be taken seriously?

Sargent:Sorry, Art, but aside from the foolish and intellectually lazy remark about mathematics, all of the criticisms that you have listed reflect either woeful ignorance or intentional disregard for what much of modern macroeconomics is about and what it has accomplished. That said, it is true that modern macroeconomics uses mathematics and statistics to understand behavior in situations where there is uncertainty about how the future will unfold from the past. But a rule of thumb is that the more dynamic, uncertain and ambiguous is the economic environment that you seek to model, the more you are going to have to roll up your sleeves, and learn and use some math. That’s life.

Are these the words of an empirical macroeconomist? I’ll be dipped! To me it sounds like the same old axiomatic-deductivist mumbo jumbo that parades as economic science of today.

Neoclassical economic theory today is in the story-telling business whereby economic theorists create make-believe analogue models of the target system – usually conceived as the real economic system. This modeling activity is considered useful and essential. Since fully-fledged experiments on a societal scale as a rule are prohibitively expensive, ethically indefensible or unmanageable, economic theorists have to substitute experimenting with something else. To understand and explain relations between different entities in the real economy the predominant strategy is to build models and make things happen in these “analogue-economy models” rather than engineering things happening in real economies.

Formalistic deductive “Glasperlenspiel” can be very impressive and seductive. But in the realm of science it ought to be considered of little or no value to simply make claims about the model and lose sight of reality.

Neoclassical economics has since long given up on the real world and contents itself with proving things about thought up worlds. Empirical evidence only plays a minor role in economic theory, where models largely function as a substitute for empirical evidence. But “facts kick”, as Gunnar Myrdal used to say. Hopefully humbled by the manifest failure of its theoretical pretences, the one-sided, almost religious, insistence on axiomatic-deductivist modeling as the only scientific activity worthy of pursuing in economics will give way to methodological pluralism based on ontological considerations rather than formalistic tractability.

Although the critique put forward here on mainstream macroeconomics in general and Real Business Cycles Theory in particular may be upsetting for die hard neoclassicals, we shouldn’t forget that the critique isn’t really new. More than fifty years before the birth of Real Business Cycles Theory, Irving Fisher – in Booms and Depressions (1932) – expressed severe doubts on similar bold attempts at a unified growth-cycles theory:

In times of depression, is the soil less fertile? Not at all. Does it lack rain? Not at all. Are the mines exhasuted? No, they can perhaps pour out even more than the old volume of ore, if anyone will buy. Are the factories, then, lamed in some way – down at the heel? No; machinery and invention may be at the very peak.

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