興太郎 鈴村’s research while affiliated with Hitotsubashi University and other places

First Draft: 25 July 2003; This Revision: 22 September 2003 21世紀COEプログラム = 21st-Century COE Program Revised: 22 September 2003

This version May 2008 An extended social choice framework is proposed for the analysis of initial conferment of individual rights. It captures the intuitive conception of decisionmaking procedure as a carrier of intrinsic value along with the instrumental usefulness thereof in realizing valuable culmination outcomes. Our model of social decision-making consists of two stages. In the first stage, the society decides on the game form rights-system to be promulgated. In the second stage, the promulgated game form rights-system, coupled with the revealed profile of individual preference orderings over the set of culmination outcomes, determines a fully-fledged game, the play of which determines a culmination outcome at the Nash equilibrium. A set of sufficient conditions for the existence of a democratic social choice procedure, which chooses a game form in the first stage that is not only liberal, efficient and Nash solvable, but also uniformly workable for every revealed profile of individual preference orderings over the set of culmination outcomes, is identified.

We characterize a class of collective choice rules such that collective preference relations are consistent. Consistency is a weakening of transitivity and a strengthening of acyclicity requiring that there be no cycles with at least one strict preference, which excludes the possibility of a “money pump.” The properties of collective choice rules used in our characterization are unrestricted domain, strong Pareto, anonymity and neutrality. If there are at most as many individuals as there are alternatives, the axioms provide an alternative characterization of the Pareto rule. If there are more individuals than alternatives, however, further rules become available.

This version February 2008 21世紀COEプログラム = 21st-Century COE Program

March 28, 2007 21世紀COEプログラム = 21st-Century COE Program

This Version: August 2006 Most, if not at all, practitioners of welfare economics and social choice theory are presumed to be welfaristic in their conviction. Indeed, they evaluate the goodness of an economic policy and/or economic system in terms of the welfare that people receive at the culmination outcomes thereby generated. Recent years have witnessed a substantial upsurge of interest in the non-welfaristic bases, or even the non-consequentialist bases, of welfare economics and social choice theory. Capitalizing on the axiomatic approach which we explored in the recent past, we try to provide a coherent analysis of consequentialism vis-à-vis non-consequentialism. To begin with, we develop an abstract framework in which the primitive of our analysis is a preference ordering held by an evaluator over the pairs of culmination outcomes and opportunity sets from which those culmination outcomes are chosen. As a partial test to see how much relevance can be claimed of the axiomatized concepts of consequentialism and non-consequentialism, two simple applications of this abstract framework are worked out. The first application is to the Arrovian social choice theory and the second application is to the analysis of ultimatum games. 科学研究費補助金（特別推進研究） = Grant-in-Aid for Specially Promoted Research

The rationalizability of a choice function on arbitrary domains by means of a transitive relation has been analyzed thoroughly in the literature. Moreover, characterizations of various versions of consistent rationalizability have appeared in recent contributions. However, not much seems to be known when the coherence property of quasi-transitivity or that of P-acyclicity is imposed on a rationalization. The purpose of this paper is to fill this significant gap. We provide characterizations of all forms of rationalizability involving quasi-transitive or P-acyclical rationalizations on arbitrary domains.

21世紀COEプログラム = 21st-Century COE Program

This Version June 2004 Bibliography: p. 27-29 We examine the possibility of constructing social ordering functions, each of which associates a social ordering over the feasible pairs of allocations and allocation rules with each simple production economy. Three axioms on the admissible class of social ordering functions are introduced, which embody the values of procedural fairness, non-welfaristic egalitarianism, and welfaristic consequentialism, respectively. The logical compatibility of these axioms and their lexicographic combinations subject to constraints are examined. Two social ordering functions which give priority to procedural values rather than to consequential values are identified, which can uniformly rationalize a nice allocation rule in terms of the values of procedural fairness, non-welfaristic egalitarianism, and Pareto efficiency.

An extended social choice framework is proposed for the analy-sis of libertarian assignment of individual rights in the primordial stage of rule selection. The crucial concepts of our framework are the extended social states, viz. the pairs of narrowly defined social states and the mechanisms through which narrowly defined social states are chosen, and the extended constitution function which aggregates each profile of individual ordering functions into a so-cial ordering function. A set of necessary and sufficient conditions for the existence of an extended constitution function, which is uniformly rational and chooses a minimally libertarian assign-ment of individual rights, is identified.