What do mainstream economists think about the minimum wage?

A third think it's bad, while slightly less than a quarter think it's fine. Or so it seems according to David Colander. In the update of his 1987 analysis of "The Making of an Economist" (original one with Arjo Klamer; subscription required) David asked graduate students what did they think about several economic issues (a short version here; the book here). I have some doubts about David's new overall conclusion about the state of the profession, in particular his views on how the profession has changed (see for example my debate here), but there are several interesting points raised by the replies given by the graduate students of 6 mainstream programs. One is related to their views about the minimum wage.

The table (from the book) shows the views then (1987) and now (2005), by publication dates, on whether the minimum wage increases unemployment among young unskilled workers. The evidence seems to suggest overall there is not much of a change, with 34% back then and 33% now agreeing with the conventional neoclassical proposition. But a small change suggests that more economists believe that the minimum wage does NOT lead to unemployment now, from 18% to 23%. In Chicago the percentage of graduate students holding a conventional view fell from 70% to 56%. Only Harvard seems to go in the opposite direction. MIT shows the biggest increase among those that disagree with the conventional view (from 11% to 30%).

There are several problems with the conventional mainstream (marginalist) story about the effects of minimum wages. The capital debates actually are relevant here too. There is no reason to believe that firms will hire more workers when the price of labor falls, exactly for the same reasons that hold for capital. The principle of substitution does not necessarily work, and there is no relation between the intensity of the use of a factor of production (labor) and its remuneration (real wage). Put in simple terms, there is no reason to hire workers, even if their wages are lower, if there is no demand for your products.

But the reasons for the change in views, small as they are, are not related to the logical flaws of the mainstream model. I don't even think it is solely the increasing evidence since the publication of Card and Krueger's analysis (here; discussed here too), about the absence of a negative effect of minimum wage increases on employment, that has been the driving force in these changing views. My guess is that income inequality has played a role in the willingness of mainstream students to reject the conclusions of the theory they are taught. But in order to really know why, we would need another survey.

ISLM: what is it good for?

The ISLM model persists in most undergraduate textbooks, and even though it has vanished from graduate courses*, it remains central to the way economists think about policy issues.  The main reason it survives is not so much that it allows a relatively simple intro to policy issues to undergrads, as some argue, but the fact that it captures the interaction between real and monetary phenomena which was central for Keynes’ General Theory (still worth reading), and is flexible enough to accommodate divergent views, often reflected in different inclinations of the curves.

It is also true that the conventional interpretation of the ISLM is fraught with problems.  But the ISLM model is incredibly flexible and can accommodate most critiques.  For example, a few years back a reader asked Mankiw why he still taught that the Fed controls money supply, rather than control the rate of interest, which would be more relevant.  His reply was not particularly good (just an ad for his book), but the fact remains that it is easy to change the LM to reflect the fact that central banks control the rate of interest.  The ISLM with a horizontal LM is sometimes referred to as the ISMP, where MP stands for monetary policy rule, and for the most part this is done for the benefit of students (i.e. you can buy the new text with the updated ISMP model for $150!).

The ISLM can also accommodate an investment function in which the level of activity, rather than the rate of interest, is central, which is more empirically accurate, and different consumption functions in which other elements besides disposable income appear.  More importantly the ISLM does not imply a natural rate of unemployment, which often appears in the supply side part of the macro course.  In other words, the ISLM allows for relevant discussion of policy issues, and clarification of policy differences.  Besides, compare this model with the consumption theory you get in micro, and this is still one of the most relevant things you can learn in economics.  The other would be not to trust economists!

* David Colander suggests that it’s not taught in graduate courses because more sophisticated dynamic stochastic general equilibrium models (DSGE) are more important.  DSGE models are based on the aggregation of individual maximizing behavior, and have been less relevant for policy analysis than old fashion macroeconometric models based on the old Keynesian theory.  The whole conference on the ISLM, in which you can find Colander’s paper is available here

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