Ranking opportunity sets on the basis of their freedom of choice and their ability to satisfy preferences: A difficulty

This paper examines a possibility of enlarging the domain of definition of individual preferences suggested by the recent literature on freedom of choice. More specifically, the possibility for an individual to have preferences that depend upon both the opportunity set that she faces and the particular alternative that she chooses from that set is considered. Even more specifically, the possibility for these preferences to value freedom of choice, as defined by the set theoretic relation of inclusion, while being consistent, in a certain sense, with the existence of a preference ordering over the options contained in opportunity sets is investigated. It is shown in the paper that a necessary condition for the existence of any transitive extended preferences of this type is for freedom of choice to be given no intrinsic importance. Received: 22 November 1995 / Accepted: 11 January 1997     

Freedom to veto

Several sets of axioms have been proposed to characterize rankings of opportunity sets in terms of freedom of choice. In these models it has been assumed that being in a position to choose from more options is preferred to having fewer options. We tested the empirical validity of that assumption experimentally. Combining a dictator game (a no-choice situation for the receiver) and an ultimatum game (the receiver can choose between two options) we investigated whether receivers prefer to have some freedom of choice (in the ultimatum game) over having no freedom of choice (in the dictator game) even in the presence of monetary incentives to choose otherwise. The experimental results show that a strong majority of players is not willing to give up the option to veto without monetary incentives to do so. However, players are often willing to trade their freedom to veto even for a small bonus. The higher the monetary incentives the more players give up their veto power.     

Congruence indicators for fuzzy choice functions

We introduce the congruence indicators WFCA(·) and SFCA(·) corresponding to fuzzy congruence axioms WFCA and SFCA. These indicators measure the degree to which a fuzzy choice function verifies the axioms WFCA and SFCA, respectively. The main result of the paper establishes for a given choice function the relationship between its congruence indicators and some rationality conditions. One obtains a fuzzy counterpart of the well-known Arrow–Sen theorem in crisp choice functions theory.     

Axiomatizations of the normalized Banzhaf value and the Shapley value

A cooperative game with transferable utilities– or simply a TU-game – describes a situation in which players can obtain certain payoffs by cooperation. A solution concept for these games is a function which assigns to every such a game a distribution of payoffs over the players in the game. Famous solution concepts for TU-games are the Shapley value and the Banzhaf value. Both solution concepts have been axiomatized in various ways. An important difference between these two solution concepts is the fact that the Shapley value always distributes the payoff that can be obtained by the `grand coalition' consisting of all players cooperating together while the Banzhaf value does not satisfy this property, i.e., the Banzhaf value is not efficient. In this paper we consider the normalized Banzhaf value which distributes the payoff that can be obtained by the `grand coalition' proportional to the Banzhaf values of the players. This value does not satisfy certain axioms underlying the Banzhaf value. In this paper we introduce some new axioms that characterize the normalized Banzhaf value. We also provide an axiomatization of the Shapley value using similar axioms. Received: 10 April 1996 / Accepted: 2 June 1997     

Axiomatic foundations for fairness-motivated preferences

Much work in social choice theory takes individual preferences as uninvestigated inputs into aggregation functions designed to reflect considerations of fairness. Advances in experimental and behavioural economics show that fairness can also be an important motivation in the preferences of individuals themselves. A proper characterisation of how fairness concerns enter such preferences can enrich the informational basis of many social choice exercises. This paper proposes axiomatic foundations for individual fairness-motivated preferences that cover most of the models developed to rationalise observed behaviour in experiments. These models fall into two classes: Outcome-based models, which see preferences as defined only over distributive outcomes, and context-dependent models, which allow rankings over distributive outcomes to change systematically with non-outcome factors. I accommodate outcome-based and context-sensitive fairness concerns by modelling fairness-motivated preferences as a reference-dependent preference structure. I first present a set of axioms and two theorems that generate commonly used outcome-based models as special cases. I then generalise the axiomatic basis to allow for reference-dependence, and derive a simple functional form in which the weight on each person’s payoff depends on a reference vector of how much each person deserves.     

Social compromise and social metrics

In the context of constitutional design, a committee of citizens' representatives proposes (social choice) axioms. The outcome should not necessarily be the aggregation rule, or rules, satisfying each of the axioms. Alternative procedures are recommended for aggregating a set of axioms into a single summary axiom. The summary axiom generates a single social decision function when a social metric is applied.     

Reference functions and possibility theorems for cardinal social choice problems

 In this paper, we provide axiomatic foundations for social choice rules on a domain of convex and comprehensive social choice problems when agents have cardinal utility functions. We translate the axioms of three well known approaches in bargaining theory (Nash 1950; Kalai and Smorodinsky 1975; Kalai 1977) to the domain of social choice problems and provide an impossibility result for each. We then introduce the concept of a reference function which, for each social choice set, selects a point from which relative gains are measured. By restricting the invariance and comparison axioms so that they only apply to sets with the same reference point, we obtain characterizations of social choice rules that are natural analogues of the bargaining theory solutions. Received: 8 August 1994/Accepted: 12 February 1996     

Consistency between tastes and values: A universalization approach

The object of this paper is to propose a consistency test for an individual involved in collective choice process. Collective choice processes considered in the paper are those that transform individuals ‘tastes’– which reflect the self-interested view point of the individuals – into (social) ranking of alternatives. In addition to her tastes, an individual has values about the way by which collective decision should be made. We distinguish two categories of such values. First, there are end-values that restrict the class of social rankings that the individual considers ethically acceptable. Second there are aggregation-values that specify the way by which the social ranking should depend upon the individuals tastes. The consistency test stands on an hypothetical operation of universalization of the individual tastes to everyone. Five illustrations of the potential usefulness of our approach for interpreting social choice theory and welfare economics are proposed. These illustrations deal with utilitarian aggregation in the presence of income inequality aversion, the so-called ‘ethics of responsibility’ and the aggregation of individual ranking of opportunity sets based on their freedom of choice. A discussion of the relevance of the consistency test for addressing the problem of ‘laundering’ individual preferences is also provided. Received: 25 June 1998/Accepted: 16 March 1999     

Social threshold aggregations

A problem of axiomatic construction of a social decision function is studied for the case when individual opinions of agents are given as m-graded preferences with arbitrary integer m ≥ 3. It is shown that the only rule satisfying the introduced axioms of Pairwise Compensation, Pareto Domination and Noncompensatory Threshold and Contraction is the threshold rule.     

On Preference, Freedom and Diversity

We study the problem of ranking sets of options in terms of freedom of choice. We propose a framework in which both the diversity of the options and the preferences of the agent over the options do play a role. We formulate some axioms that reflect these two aspects of freedom and we study their logical implications. Two different criteria for ranking sets are characterized, which generalize some of the rankings proposed so far in the literature.     

On ranking opportunity distributions

Our results show the intimate relationship between a large group of apparently different rankings of opportunity distributions. First, we provide a set of core basic axioms that are intuitively plausible under any concern for equality or efficiency aspects. Second, we introduce two very opposed views of the problem by incorporating different perspectives of the notion of advantage (better opportunity set) and we provide some axioms that might be defended under such extreme positions. For any of these two different perspectives, we characterize the families of rankings which satisfy the core axioms and the group of axioms corresponding to that view. These characterizations will prove insightful to better understand most of the criteria already introduced in the literature, which are part of the families we study.     

Top-Pair and Top-Triple Monotonicity

We say that a social choice function (SCF) satisfies Top-k Monotonicity if the following holds. Suppose the outcome of the SCF at a preference profile is one of the top k-ranked alternatives for voter i. Let the set of these k alternatives be denoted by B. Suppose that i’s preference ordering changes in such a way that the set of first k-ranked alternatives remains the set B. Then the outcome at the new profile must belong to B. This definition of monotonicity arises naturally from considerations of set “improvements” and is weaker than the axioms of strong positive association and Maskin Monotonicity. Our main results are that if there are two voters then a SCF satisfies unanimity and Top-2 or Top-pair Monotonicity if and only if it is dictatorial. If there are more than two voters, then Top-pair Monotonicity must be replaced by Top-3 Monotonicity (or Top-triple Monotonicity) for the analogous result. Our results demonstrate that connection between dictatorship and “improvement” axioms is stronger than that suggested by the Muller–Satterthwaite result (Muller and Satterthwaite in J Econ Theory 14:412–418, 1977) and the Gibbard–Sattherthwaite theorem.     

Agreement, separability, and other axioms for quasi-linear social choice problems

A quasi-linear social choice problem is concerned with choosing one among a finite set of public projects and determining side payments among agents to cover the cost of the project, assuming each agent has quasi-linear preferences. We first investigate the logical relations between various axioms in this context. They are: agreement, separability, population solidarity, consistency, converse consistency, and population-and-cost solidarity. Also, on the basis of these axioms, we present alternative characterizations of egalitarian solutions; each solution assigns to each agent an equal share of the surplus derived from the public project over some reference utility level, but uses a different method to compute the reference utility level. Received: 18 May 1998/Accepted: 1 July 1999     

Themed section: the person-centred turn in welfare policies: bad wine in new bottles or a true social innovation?

This themed section is aimed at evaluating different personalised policies and at drawing a clear map of opportunities and challenges for future implementations. All the essays are based on evaluative researches and on original case studies. They concern different policies: the Australian National Disability Scheme (NDIS) a first serious venture into personalised funding; personalisation in the management of offenders in probation services within the English criminal justice system; social care services for young disabled people attempting to personalise their transition from childhood into adulthood (in Redbridge, UK); health personal plans for disabled people (in Sardinia, Italy). These case studies address the question of how transferable the concept of personalisation is from the social care sector to other and outline different methodologies for developing and evaluating person-centred policies. Last but not least they reflect on a bundle of issues which seem to emerge autonomously from such different case studies. We can sum up their results affirming that personalisation is not an individual consumer-client technology, simply confronted with a single market context and new professionals. It has to be steered within an appropriate context, including new type of professionals, users' led associations and a new governance's architecture. If the public role has to shape freedom and control, helping people to exercise choice in a collectively responsible way and, consequently, to participate in creating public goods, then the person-centred turn will have to confront, at least, some emergent issues, which in turn need specific forms of governance.     

Coordinated Action in the Massively Multiplayer Online Game World of Warcraft

In tandem with the technological advancement of immersive virtual environments, digital games have evolved into complex social worlds where people play collaboratively to achieve individual‐ and group‐oriented goals. The massively multiplayer online games genre has received international attention for the large numbers of users that commit a significant amount of time and effort to online play. Play styles within such game worlds are diverse, but “raiding” is generally considered among gamers and scholars alike to be the most challenging form of collaborative play. Like other forms of social activity, raiding is predicated on players' abilities to successfully coordinate individual lines of action. Yet the vast majority of raiders are not physically copresent during their collaborative efforts. Using Couch's theory of coordinated action as an interpretive frame, we explore the computer‐mediated process of raiding in the massively multiplayer online game World of Warcraft by analyzing ethnographic data and audio/visual recordings of gameplay. Our study expands Couch's theory of coordinated action in two ways. First, we demonstrate how individuals and groups simultaneously engage in multiple forms of coordinated activity (e.g., conflict and cooperation). Second, we reveal two semiotic layers of coordinated action—the “subject‐subject” (i.e., intersubjective) layer that is facilitated through the game's user interface, and the “subject‐object” layer that comprises players' interactions with the user interface itself. Our study thus considers the potential of Couch's theory for the study of computer‐mediated communication and nonhumans in interaction.     

Core implementation via dynamic game forms

Implementation of a social choice correspondence (SCC) involves finding a decentralized choice mechanism for which the solution is a manifestation of the SCC. We examine whether dynamic game forms with corelike solutions are feasible candidates for implementation. When the solution is the -, -, or intermediate-cores respectively, such feasibility is found to require a choice structure which embeds a sequential dictatorship, in turn implying the SCC has a partial dictator. Implementation via the strong equilibrium set is found feasible iff society consists of a single citizen. Tapering the range of permissible utility profiles to include only von Neumann-Morgenstern utilities does little to rectify these impossibility results. Effectivity functions are used as analytical tools and several new effectivity function concepts are introduced.The author is grateful for comments by Tatsuro Ichiishi and B. Kelly Eakin. Errors or shortcomings are the sole responsibility of the author.     

On the multi-preference approach to evaluating opportunities

The purpose of the paper is to provide a general framework for analyzing “preference for opportunities.” Based on two simple axioms a fundamental result due to Kreps is used in order to represent rankings of opportunity sets in terms of multiple preferences. The paper provides several refinements of the basic representation theorem. In particular, a condition of “closedness under compromise” is suggested in order to distinguish the flexibility interpretation of the model from normative interpretations which play a crucial role in justifying the intrinsic value of opportunities. Moreover, the paper clarifies the link between the multiple preference approach and the “choice function” approach to evaluating opportunities. In particular, it is shown how the well-known Aizerman/Malishevski result on rationalizability of choice functions can be obtained as a corollary from the more general multiple preference representation of a ranking of opportunity sets. Received: 3 September 1996 / Accepted: 18 August 1997     

Strategy-proof resolute social choice correspondences

We qualify a social choice correspondence as resolute when its set valued outcomes are interpreted as mutually compatible alternatives which are altogether chosen. We refer to such sets as “committees” and analyze the manipulability of resolute social choice correspondences which pick fixed size committees. When the domain of preferences over committees is unrestricted, the Gibbard–Satterthwaite theorem—naturally—applies. We show that in case we wish to “reasonably” relate preferences over committees to preferences over committee members, there is no domain restriction which allows escaping Gibbard–Satterthwaite type of impossibilities. We also consider a more general model where the range of the social choice rule is determined by imposing a lower and an upper bound on the cardinalities of the committees. The results are again of the Gibbard–Satterthwaite taste, though under more restrictive extension axioms.     

On probabilistic rationalizability

This paper examines the problem of rationalizability of a choice system without imposing restrictions on the universal set of alternatives and the family of feasible sets. A choice system is the probabilistic counterpart of a choice function which is basic to much of the theory of individual choice behaviour in economics. We provide a necessary and sufficient condition for a choice system to be induced by a probability measure on a set of utility functions. I would like to thank the editor and two anonymous referees for helpful comments.     

Partially monotonic bargaining solutions

The purpose of the paper is to study partially monotonic solutions for two-person bargaining problems. Partial monotonicity relates to the uncertainty a player has about the solution before bargaining. If the minimum utility a player can expect is greater in game T than in game S, and if T contains more alternatives than S, this may bring him to expect that his utility at the solution is greater in T than in S. Partially monotonic solutions reflect these expectations.One partially monotonic solution is axiomatized. The axioms of symmetry and independence of linear transformations are not explicitly assumed, although the solution has also these properties. The Kalai-Smorodinsky solution is shown to be the only continuous partially monotonic solution.This study was financed by the Yrjö Jahnsson Foundation, which is gratefully acknowledged. I like to thank an associate editor and a referee for their valuable suggestions, and the Yrjö Jahnsson Foundation Study Group on Public Economics for useful discussions