社会科学における誘引両立性
小林憲正 Norimasa Kobayashi
東京工業大学

社会理工学研究科

価値システム専攻

1 Incentive Compatibility (IC)The relationship between theory and reality in economics seems to exhibit features not typically found in natural sciences, which is why philosophy of experimentation in economics
may become a theme worth studying even after studying experimentation in natural sciences[4, 5]. I focus on one of the issues, that I call incentive compatibility (IC) of a stable
theory, raised in Hausman as well.
While IC is most essential and, at least implicitly, commonsensical for decent theoretical economists, little attention seems to be paid by philosophers, including Hausman
himself. In this paper I aim at showing that IC is arguably the most important feature
regarding observation and experimentation to be considered in social sciences, which isin analogy with uncertainty principle in quantum physics. I propose a happier marriage
between theory and experience in economics in Ross[7]’s manner (though my proposal isquite different from Ross’s).

2 IC and Falsifiability – On Behavioral Economics
In philosophy of natural sciences, despite the enormous complication regarding the relationship between theory and reality, it is always assumed that the real world continues
to possess the features we want to know. The theory is to be tested against reality. It isnever the other way around.
IC implies, depending on the features one wants to know about the world, that it
may be possibly the real world side that will conform to the theory, after the interaction
between the two. I argue therefore the propaganda made by seemingly large proportionof behavioral economists on the raison d’etre of their field – predictably irrational[1] – isseriously self-defeating. They should admit that: i) in the long-run thanks to their own
findings people will correct mistakes, in which case their findings will lose the predictivepower, ii) their science will have had little impact even in the far future such that virtuallyno one has had the chance to correct their mistakes via learning the research findings, oriii) their definition of rationality is inadequate, such that people have been rational in
the first place. I think case i) will continue to be one of the important raison d’etres ofpsychology – their function is to teach non-enlightened individuals.

3 IC and Falsifiability – On Economic Theory
As Backhouse[2] argues, economic theory today has little to do with falsification. The
most extreme characterization may be economic models as fables[8], which I discuss inanother occasion. Even for those that seem to be interested in policy advices in the realworld, one can define “economics as being the study of rational competitive behavior in any
institution of society”[6], although they admit without hesitation that perfect rationality
assumption has been falsified.

One positive characterization, that I find useful, for the rationality assumption, possibly along with most other applied mathematics in general, is the relevance and naturalnessof the assumption in each concrete settings. Instead of seeking for a universal explanation,
each concrete model that feel useful in one sense or another survive to be used and citedextensively. This is probably how logical positivists and applied mathematicians differ.

4 Happier Marriage between Theory and Reality
As I argued above, there is little flavor of naturalism in today’s economic theory. This looks
odd to me, when even in philosophy, foundationalism seems to give way to naturalism.
How may IC and naturalism coexist?
I find the concept of subjective cognitive definition of rationality[3] particularly promising. Research programs of ecological rationality, the concept used in quite different waysby two schools, constitute best examples [10, 9].

References[1] Dan Ariely. Predictably Irrational: The Hidden Forces That Shape Our Decisions.
HarperCollins, New York, 2008.
[2] Roger E. Backhouse. The rise and fall of popper and lakatos in economics. In Uskali
Mäki, editor, Philosophy of Economics, Handbook of the Philosophy of Science, pages
25 – 48. North-Holland, Amsterdam, 2012.
[3] Itzhak Gilboa and David Schmeidler. A Theory of Case-Based Decisions. Cambridge
University Press, Cambridge, 2001.
[4] Francesco Guala. Experimentation in economics. In Uskali Mäki, editor, Philosophy ofEconomics, Handbook of the Philosophy of Science, pages 597 – 640. North-Holland,
Amsterdam, 2012.
[5] Daniel M. Hausman. Social scientific naturalism and experimentation in economics.
In Uskali Mäki, editor, Philosophy of Economics, Handbook of the Philosophy ofScience, pages 287 – 307. North-Holland, Amsterdam, 2012.
[6] Roger B. Myerson. Nash equilibrium and the history of economic theory. Journal ofEconomic Literature, 37(3):pp. 1067–1082, 1999.
[7] Don Ross. Philosophy of economics. Palgrave Macmillan, Basingstoke, 2014.
[8] Ariel Rubinstein. Economic fables. Open Book Publishers, 2012.
[9] Vernon L Smith. Rationality in economics: constructivist and ecological forms. Cambridge University Press, New York, 2008.
[10] Peter M. Todd and Gerd Gigerenzer. Bounding rationality to the world. Journal ofEconomic Psychology, 24(2):143 – 165, 2003. The Economic Psychology of Herbert
A. Simon.