How Effective is Economic Theory?

A nice essay by Arnold Kling.

What is effective theory?

Instead of “science,” we might want to think about economics in terms of “effective theory.” As explained by Harvard physicist Lisa Randall,

Effective theory is a valuable concept when we ask how scientific theories advance, and what we mean when we say something is right or wrong. Newton’s laws work extremely well. They are sufficient to devise the path by which we can send a satellite to the far reaches of the Solar System and to construct a bridge that won’t collapse. Yet we know quantum mechanics and relativity are the deeper underlying theories. Newton’s laws are approximations that work at relatively low speeds and for large macroscopic objects. What’s more is that an effective theory tells us precisely its limitations — the conditions and values of parameters for which the theory breaks down. The laws of the effective theory succeed until we reach its limitations when these assumptions are no longer true or our measurements or requirements become increasingly precise.

Whereas the term “science” often is used to connote absolute truth in an almost religious sense, effective theory is provisional. When we are certain that in a particular context a theory will work, then and only then is the theory effective.

Effective theory consists of verifiable knowledge. To be verifiable, a finding must be arrived at by methods that are generally viewed as robust. Any researcher who tries to replicate a finding using appropriate methods should be able to confirm it. The strongest confirmation of the effectiveness of a theory comes from prediction and control. Lisa Randall’s example of sending a spacecraft to the far reaches of the solar system illustrates such confirmation.

In the end:

In the end, can we really have effective theory in economics? If by effective theory we mean theory that is verifiable and reliable for prediction and control, the answer is likely no. Instead, economics deals in speculative interpretations and must continue to do so.

This reality is far from new. But economists are still grappling with its implications. They seem to resist one implication in particular: that the claim of economists to scientific expertise is no longer tenable.

Professional economists are increasingly aware of the mental-cultural factors that affect economic behavior. As a result, they are willing to broaden their methods beyond the strict reliance on mathematical derivations and multiple regression that prevailed 40 years ago. But if economics has become less of a monoculture with respect to methods, it is now more uniform in its support for Federal Reserve technocratic efforts and for economic activism in general. In 1980, the critics of Keynesian economic policies enjoyed respect in the leading economics departments and journals. This is much less true today.

Young economists who employ pluralistic methods to study problems are admired rather than marginalized, as they were in 1980. But economists who question the wisdom of interventionist economic policies seem headed toward the fringes of the profession.

In this respect, the barriers to effective theory in economics are different and perhaps more worrisome than was the case in 1980. The contemporary state of economic theory reflects a broader crisis in the social sciences and a deepening cleavage between the college campus and the rest of society.



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