The Rationality Principle: An Attempt at Synthesis

ABSTRACT

The status and role of Popper’s ‘Rationality Principle’ (RP) is still the subject of disputes. The ‘prevailing view’ among Popper’s commentators seems to be that RP is better interpreted as a methodological principle. Yet, this view is challenged in a recent study where RP is interpreted as an‘idealization’. We critically review these two accounts of RP and propose a novel one according to which RP is, first and foremost, the scientific version of a heuristic that ordinary people unconsciously use when they seek to explain and predict other people’s behavior. However, we recognize that, to the extent RP is part of a methodological strategy whereby, in the wake of adverse empirical results, social scientists place the ‘onus of proof’ on their situational model it is legitimate to claim that RP is adopted, at least partly, for methodological reasons. Further, to the extent that the adoption of RP implies suppressing those mental processes that may affect actors’ reasoning and willpower it is also legitimate to claim that RP is, at least partly, an ‘idealization’. We conclude that the status and role of RP is multi-faceted and that the three accounts of RP complement each other.

KEYWORDS:

• Heuristic
• idealization
• methodology
• rationality principle

Acknowledgements

The author would like to thank two anonymous referees for their comments and suggestions on the manuscript. Of course, any remaining shortcomings or errors are exclusively the author’s.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Notes

1. Latsis (1983, 131) notes that, to his knowledge, Popper coined the phrase ‘Rationality Principle’.

2. Early presentations of SA are in The Open Society and its Enemies (Popper [1945] 1966; ch. 14, especially page 97), in his Poverty of Historicism (Popper 1957, sec. 31–32), in the English translation (Popper 1985) of a French paper, and in Objective Knowledge (Popper 1972a, 178–179). However, the most detailed discussion of SA and RP is in the chapter titled `Models, Instruments, and Truth: The Status of the Rationality Principle in the Social Sciences´ included in The Myth of the Framework (Popper 1994).

3. There are two additional accounts of RP advocated by several commentators: (i) the account of RP as a ‘synthetic a priori’ proposition (Hollis 1977, 89; Nadeau 1993) which is explicitly rejected by Popper (1994, 172), and (ii) the notion of RP as a ‘statistical law’ that holds true ‘on average’ (Lagueaux 1993, 470).

4. However, Weber’s notion of ‘ideal types’ is an intrinsic part of his methodological proposal for the social sciences. That is, for Weber, the use of ‘ideal types’ is also a MP. This aspect is ignored by Miller (2012) who implicitly assumes that the account of RP as an idealization is incompatible with the account of RP as a MP. We should like to thank an anonymous referee for drawing our attention to this point.

5. Among Popper’s commentators, Lagueaux (2006, 201) is, to the best of our knowledge, the only one who also seems to interpret RP as an ‘empirical conjecture’ or factual hypothesis. To illustrate this account he proposes the thought experiment of an ET who arrives on Earth and is capable of induction and deduction. As the example goes, Lagueaux (200) concludes that ‘through careful observation of the regularities in human behavior’ ET arrives at the empirical conclusion that human beings are rational.

6. Although Popper (1994, 182) presents several examples where RP is allegedly used, they do not help us shed light on whether he views RP as either an ‘empirical conjecture’ or a MP. The reason is that he uses them to illustrate SA and emphasizes the need to ‘de-psychologize the aims, information, and knowledge of the actors in typical social situations’. However, Miller (2012) uses these examples to claim support for his account of RP as an ‘idealization’.

7. Rosenberg (2012, 39–40) does not explicitly mention RP, yet he seems to hold a similar view. He identifies a principle he denotes by [L], after ‘Law’, which, according to him, underwrites both ordinary explanations in everyday life and much of the social sciences. [L] goes as follows: ‘if any person, agent, individual, wants some outcome, d, and believes that an action, a, is a means to attain d under the circumstances, then x does a’. This principle is, arguably, equivalent to RPs.

8. This version of marginal utility theory is not to be confounded with ‘subjective expected utility theory’ which was developed much later and is used to study decision-making under conditions of risk and uncertainty.

9. Following Boudon (1993, 10), instrumental or means-ends rationality is the notion that behavior is ‘rational’ if action A is the best means to attain goal G whereas cognitive rationality is the notion that ‘people often have good reasons of believing in conjectures or theories even if these reasons are fragile or ungrounded’.

10. An example in the social sciences of an ‘ideal type’ that is not observed in reality is the notion of ‘perfect competition’ in microeconomic theory.

11. Arguably, it may be for this reason that Popper (1994, 177) seems to come closest to interpreting RP as an ‘empirical conjecture’.

12. This is in contrast to methodological heuristics which Chow (2015, 997) defines as devices for ‘learning and problem-solving’, the clearest examples being models and analogies.

13. The notion of ‘folk psychology’ adopted here is discussed in Dennett (1987, ch. 3) and, especially, Rosenberg (2012, chs. 3 and 4). The latter defines it as a theory we use every day to form expectations about the behaviour of our fellow human beings (Rosenberg 2012, 36).

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Alfonso Palacio-Vera

Alfonso Palacio-Vera is an Associate Professor of Economics at Universidad Complutense de Madrid, Spain. He has been a Visiting Scholar at the University of Massachusetts and Duke University. He has published a number of papers in academic journals including the Cambridge Journal of Economics, Metroeconomica, Economics and Philosophy, Philosophy of the Social Sciences, International Studies in the Philosophy of Science, Journal of Post Keynesian Economics, Journal of Economic Issues, Review of Political Economy, Eastern Economic Journal, and International Review of Applied Economics. He has also published some chapters in books by Palgrave Macmillan and Edward Elgar. His current scholarship is in the field of the methodology and philosophy of economics and the social sciences.