Tag Archives: John Maynard Keynes

Models Make Economics A Science

In the Journal of Economic Literature, Ariel Rubinstein discusses Dani Rodrik’s “superb” book “Economics Rules.” The article nicely articulates what economics and specifically, economic modeling is about. Some quotes (emphasis my own) …

… on the nature of economics:

[A] quote … by John Maynard Keynes to Roy Harrod in 1938: “It seems to me that economics is a branch of logic, a way of thinking”; “Economics is a science of thinking in terms of models joined to the art of choosing models which are relevant to the contemporary world.”

[Rodrik] … declares: “Models make economics a science” … He rejects … the … common justification given by economists for calling economics a science: “It’s a science because we work with the scientific method: we build hypotheses and then test them. When a theory fails the test, we discard it and either replace it or come up with an improved version.” Dani’s response: “This is a nice story, but it bears little relationship to what economists do in practice …”

… on models, forecasts, and tests:

A good model is, for me, a good story about an interaction between human beings …

A story is not a tool for making predictions. At best, it can help us realize that a particular outcome is possible or that some element might be critical in obtaining a particular result. … Personally, I don’t have any urge to predict anything. I dread the moment (which will hopefully never arrive) when academics, and therefore also governments and corporations, will be able to predict human behavior with any accuracy.

A story is not meant to be “useful” in the sense that most people use the word. I view economics as useful in the sense that Chekhov’s stories are useful—it inspires new ideas and clarifies situations and concepts. … [Rodrik] is aware … “Mischief occurs when economists begin to treat a model as the model. Then the narrative takes on a life of its own and becomes dislodged from the setting that produced it. It turns into an all-purpose explanation that obscures alternative, and potentially more useful, story lines”.

A story is not testable. But when we read a story, we ask ourselves whether it has any connection to reality. In doing so, we are essentially trying to assess whether the basic scenario of the story is a reasonable one, rather than whether the end of the story rings true. … Similarly, … testing an economic model should be focused on its assumptions, rather than its predictions. On this point, I am in agreement with Economics Rules: “. . . what matters to the empirical relevance of a model is the realism of its critical assumptions”.

… on facts:

The big “problem” with interpreting data collected from experiments, whether in the field or in the lab, is that the researchers themselves are subject to the profession’s incentive system. The standard statistical tests capture some aspects of randomness in the results, but not the uncertainty regarding such things as the purity of the experiment, the procedure used to collect the data, the reliability of the researchers, and the differences in how the experiment was perceived between the researcher and the subjects. These problems, whether they are the result of intentional sleight of hand or the natural tendency of researchers to ignore inconvenient data, make me somewhat skeptical about “economic facts.”

Roger Farmer’s “Prosperity for All”

On his blog, Roger Farmer advertizes his new book, “Prosperity for All,” and argues that governments should stabilize asset prices:

Following the Great Stagflation of the 1970s, economists backtracked and revived the classical economic theory that had dominated academic economics for a hundred and fifty years, beginning with Adam Smith in 1776 and culminating in the business cycle theory described by Keynes’s contemporary Arthur Pigou in his 1927 book, Industrial Fluctuations. That backtrack was a big mistake. It is time to realize that much, but not all, of Keynesian economics is correct. …

In my book Prosperity for All: How to Prevent Financial Crises, … I do not conclude that more government spending is the right way to cure a depression. Instead, I argue for a new policy in which central banks and national treasuries systematically intervene in financial markets to prevent the swings in asset prices that have such debilitating effects on all of our lives.

The control of asset prices will seem like a bold step to some, but so too did the control of the interest rates by the Open Market Committee of the Federal Reserve System when it was first introduced in 1913. We do not have to accept hyperinflations of the kind that occurred in 1920s Germany. Nor should we be content with the 50% unemployment rates that plague young people in Greece today. By designing a new institution, based on the modern central bank, we can and must ensure Prosperity for All.

And in another post:

The New Keynesian agenda is the child of the neoclassical synthesis and, like the IS-LM model before it, New Keynesian economics inherits the mistakes of the bastard Keynesians. It misses two key Keynesian concepts: (1) there are multiple equilibrium unemployment rates and (2) beliefs  are fundamental. My work brings these concepts back to center stage and integrates the Keynes of the General Theory with the microeconomics of general equilibrium theory in a new way.