ABSTRACT
One must admit that methodological papers rarely have a considerable and immediate impact on the practices of economists, but if we are looking for an exception to this rule, the example that comes to mind is surely Milton Friedman’s famous 1953 essay (Friedman 1953), which, apparently, was enthusiastically perceived of as a liberating piece by most economists. This enthusiasm is understandable: this paper written by a respected economist proposed relatively sophisticated arguments in favour of the legitimacy of the neoclassical practice consisting in assuming that people are rational in the sense of being maximizers, in spite of the admittedly unrealistic character of such an assumption. And the fact that these arguments were based on suggestive comparisons with the practice attributed to natural scientists was in itself powerfully reassuring for economists who did not want to put aside their secret ambition of being perceived as genuine scientists, in spite of their relatively weak propensity to base their analyses on factual inquiries and their clear preference for speculations bearing on the highly idealized world of rationality-maximization and rationality-consistency. However, Friedman’s paper was also the subject of unending and rarely very sympathetic discussion emerging from methodologists of economics and frequently enough from fellow economists as well. A significant number of papers were devoted to analysing this essay usually described as brilliant but misleading, somewhat confused and written by an author who was not too familiar with important developments in philosophy of sciences. In fact, discussions on this paper have occupied such a place in methodological debates that many methodologists became literally fed up with such discussions. Thus, readers who are in this situation and who are familiar with most objections that have been raised against Friedman’s thesis might skip this chapter without incurring too much damage for the understanding of the whole book. I think, nonetheless, that it might be worthwhile to pay attention to this chapter, which proposes some arguments that significantly differ from those that are usually opposed to Friedman’s approach.1 Let us note to start with that it is not my purpose here, far from it, to refer disparagingly to Friedman’s methodological essay. Even its most negative critics easily acknowledge that it is full of bold and fresh ideas – some of them quite original and even ahead of their time – that are formulated in an exceptionally
ingenious and attractive fashion.2 It is nonetheless important to show why the reassuring conclusions of this essay cannot be accepted so easily and also why it became the source of such an almost emotional debate that has divided methodologists of economics for more than half a century. In order to understand why the question was so passionately debated, one must realize that what was at stake in this long debate was not a simple technical point, but the very possibility of treating economics as a positive science, just like the natural sciences. After a relatively standard discussion of what allows us to characterize a science as positive, Friedman develops an argumentation against those who objected to the positive character of economics. This argumentation was exposed in a few provocative general considerations aiming to show that it is totally inappropriate to require that assumptions of a science be realistic. This thesis was then illustrated with the help of three colourful examples devised to show that their admittedly unrealistic assumptions do not contribute to making economics less ‘positive’ than any other science. It seems very probable that these examples were mostly responsible for the essay’s enduring influence over economists, but it is the general considerations that were at the core of the debate. These considerations quickly became the target of most commentators whose objections were frequently rather harsh; other commentators, however, maintain that Friedman’s views were the expression of a more palatable philosophical language, especially by presenting Friedman’s essay as a particularly clever ‘instrumentalist’3 response to the damaging consequences that a too demanding realist approach can have on the practice of economics as well as on the practice of any science.4 In order to reduce the confusion around this unending debate, without pretending to propose a definitive interpretation of the many ambiguous passages that have provoked it, my claims will be the three following:
1 Friedman’s most influential thesis seems to confuse a fundamental assumption with some consequences derived from it, in such a way that when he rightly claims that a fundamental assumption does not need to be tested other than by its implications, he wrongly considers that it is mistaken to check whether something which is implied by such an assumption obtains;
2 Friedman’s main thesis in this paper is in no way substantiated by his three famous examples: these examples could even be used to establish radically opposite conclusions;
3 instrumentalism as a philosophy of the physical sciences is quite different from the ‘instrumentalism’5 that was associated with Friedman’s views,6 which raises different and even more serious problems.
