Epistemological Implementation of Social Choice Functions

Posted: 25 Aug 2021 Last revised: 21 Nov 2022

See all articles by Hitoshi Matsushima

Hitoshi Matsushima

University of Tokyo - Faculty of Economics

Date Written: July 20, 2021


We investigate the implementation of social choice functions (SCFs) from an epistemological perspective. We consider the possibility that in higher-order beliefs there exists an honest agent who is motivated by intrinsic preference for honesty as well as material interest. We assume weak honesty, in that, although any honest agent has a cost of lying that is positive but close to zero, she (or he) is mostly motivated by material interests and even tells white lies. This study assumes that all agents are fully informed of the physical state, but “all agents are selfish” never happens to be common knowledge in epistemology. We show the following positive results for the implementability: with three or more agents, any SCF is uniquely implementable in the Bayesian Nash equilibrium (BNE). An SCF, whether material or nonmaterial (ethical), can be implemented even if all agents are selfish and “all agents are selfish” is mutual knowledge.

Keywords: unique implementation, weak honesty, common knowledge on selfishness, ethical social choice function, quadratic scoring rule

JEL Classification: C72, D71, D78, H41

Suggested Citation

Matsushima, Hitoshi, Epistemological Implementation of Social Choice Functions (July 20, 2021). Games and Economic Behavior, Vol. 136, 2022, Available at SSRN: https://ssrn.com/abstract=3892938 or http://dx.doi.org/10.2139/ssrn.3892938

Hitoshi Matsushima (Contact Author)

University of Tokyo - Faculty of Economics ( email )

7-3-1 Hongo, Bunkyo-ku
Tokyo 113-0033

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