The veto mechanism in atomic differential information economies

We establish new characterizations of Walrasian expectations equilibria based on the veto mechanism in the framework of differential information economies with a complete finite measure space of agents. We show that it is enough to consider the veto power of a single coalition, consisting of the entire set of agents, to obtain the Aubin private core. Moreover, we investigate on the veto power of arbitrarily small and big coalitions, providing an extension to mixed markets of well known Schmeidler (1972) and Vind’s (1972) results in terms of Aubin private core allocations.     

Strategy-proofness on restricted separable domains

We study a problem in which a group of voters must decide which candidates are elected from a set of alternatives. The voters’ preferences on the combinations of elected candidates are represented by linear orderings. We propose a family of restrictions of the domain of separable preferences. These subdomains are generated from a partition that identifies the friends, enemies and unbiased candidates for each voter. We characterize the family of social choice functions that satisfy strategy-proofness and tops-onlyness properties on each of the subdomains. We find that these domain restrictions are not accompanied by an increase in the family of social choice functions satisfying the two properties.     

Implementation of solutions to the problem of fair division when preferences are single-peaked

We consider the problem of fairly allocating an infinitely divisible commodity among a group of agents with single-peaked preferences. We address the issue of (Nash)-implementability of solutions to this problem. As the lack of monotonicity of preferences often causes solutions to violate no veto power, the classic Maskin-type theorems cannot be invoked. Instead, we show that more powerful theorems due to Danilov-Yamato and Sjöström can help settle implementation questions for most of the central fairness concepts, generally in the positive.     

Hierarchies of power in non-binary social choice

In the context of fixed agenda social choice correspondences, and by imposing usual axioms, we prove that power is distributed among either a non-complete hierarchy of dictators or of individuals with veto power in the society, which allows us to explicitly describe the social choice set as an alternative maximization process.     

Sufficient conditions for Nash implementation

Given an objective for a group of three or more agents that satisfies monotonicity and no veto power, Maskin (1977) proposes a two-step procedure for constructing a game that implements the objective in Nash equilibrium. The first step specifies the strategy set of the game and three properties of the game rule that are together sufficient to insure Nash implementation of the objective. The second step is the explicit construction of a game that has these properties. An example is presented here that shows that the constructed game of the second step need not have one of the three properties of the first step, and it does in fact not Nash implement the objective in the example. The problem is attributable to restricted preferences. A solution proposed here is to appropriately expand the domain of definition of the objective. This insures that the constructed game has the properties of the game in Maskin's first step, and it therefore Nash implements the original objective.     

Voting power in municipal annexation elections

In many American states, municipal annexation and consolidation require concurrent majority votes of all affected jurisdictions. The effectiveness and fairness of this voting procedure have been criticized on the grounds that a small minority of voters can frustrate the preferences of the overall majority. This paper investigates the extent to which the relative ability of voters in large and small jurisdictions to influence voting outcomes in procedures requiring concurrent majorities is influenced by jurisdictional size. The Banzhaf index, which counts the number of case4s in which a given voter could reverse the overall group decision by changing positions on an issue, is applied to this problem of concurrent voting majorities. Mathematical analysis indicates that the ratio of power between voters in small and large jurisdictions approximately equals the inverse of the square root of the ratio of their population size.     

Ambiguity in election games

We construct a model in which the ambiguity of candidates allows them to increase the number of voters to whom they appeal. We focus our analysis on two points that are central to obtain ambiguity in equilibrium: restrictions on the beliefs that candidates can induce in voters, and intensity of voters' preferences. The first is necessary for a pure strategy equilibrium to exist, while the second is necessary for ambiguity in equilibrium when there exists a Condorcet winner in the set of pure alternatives (e.g. the spatial model of electoral competition), and when candidates' only objective is to win the election. In this last case, an ambiguous candidate may offer voters with different preferences the hope that their most preferred alternative will be implemented. We also show that if there are sufficiently many candidates or parties, ambiguity will not be possible in equilibrium, but a larger set of possible policies increases the chance that at least one candidate will choose to be ambiguous in equilibrium. We would like to thank Alberto Alesina, Antonio Cabrales, Steve Coate, Olivier Compte, Tim Feddersen, Itzhak Gilboa, Joe Harrington, Michel Le Breton, Alessandro Lizzeri, George Mailath, Steve Matthews, Steve Morris, Ignacio Ortuno, Tom Palfrey, Larry Samuelson, Murat Sertel, Fernando Vega, Eyal Winter and an anonymous referee for helpful comments. The first author acknowledges financial support from DGICYT-PB 95-0983. This work was done while the first author was visiting the Center in Political Economy at Washington University, and visiting the Center for Basic Research in the Social Sciences at Harvard University. Their hospitality is gratefully acknowledged. The support of the second author's research by the National Science Foundation is also gratefully acknowledged.     

Theorems on the core of an economy with infinitely many commodities and consumers

It is known that the classical theorems of Grodal [Grodal, B., 1972. A second remark on the core of an atomless economy. Econometrica 40, 581–583] and Schmeidler [Schmeidler, D., 1972. A remark on the core of an atomless economy. Econometrica 40, 579–580] on the veto power of small coalitions in finite dimensional, atomless economies can be extended (with some minor modifications) to include the case of countably many commodities. This paper presents a further extension of these results to include the case of uncountably many commodities. We also extend Vind’s [Vind, K., 1972. A third remark on the core of an atomless economy. Econometrica 40, 585–586] classical theorem on the veto power of big coalitions in finite dimensional, atomless economies to include the case of an arbitrary number of commodities. In another result, we show that in the coalitional economy defined by an atomless individualistic model, core–Walras equivalence holds even if the commodity space is non-separable. The above-mentioned results are also valid for a differential information economy with a finite state space. We also extend Kannai’s [Kannai, Y., 1970. Continuity properties of the core of a market. Econometrica 38, 791–815] theorem on the continuity of the core of a finite dimensional, large economy to include the case of an arbitrary number of commodities. All of our results are applications of a lemma, that we prove here, about the set of aggregate alternatives available to a coalition. Throughout the paper, the commodity space is assumed to be an ordered Banach space which has an interior point in its positive cone.     

Effort estimation for enterprise resource planning implementation projects using social choice – a comparative study

ERP implementation projects have received enormous attention in the last years, due to their importance for organisations, as well as the costs and risks involved. The estimation of effort and costs associated with new projects therefore is an important topic. Unfortunately, there is still a lack of models that can cope with the special characteristics of these projects. As the main focus lies in adapting and customising a complex system, and even changing the organisation, traditional models like COCOMO can not easily be applied. In this article, we will apply effort estimation based on social choice in this context. Social choice deals with aggregating the preferences of a number of voters into a collective preference, and we will apply this idea by substituting the voters by project attributes. Therefore, instead of supplying numeric values for various project attributes, a new project only needs to be placed into rankings per attribute, necessitating only ordinal values, and the resulting aggregate ranking can be used to derive an estimation. We will describe the estimation process using a data set of 39 projects, and compare the results to other approaches proposed in the literature.     

Vertical externalities and control of politicians

A major role of (repeated) elections is to create incentives for politicians to act in the interests of voters. This paper considers the disciplining role of elections in countries with either one or two levels of government. Simple retrospective voting strategies which are based on cut-off levels with respect to expenditure and tax rates are considered. It is shown that the power of voters is weakened if a second independent level of government is added. However, voters can partially reinforce their power by making politicians not only liable for their own policy, but also for the policy carried out at each other level of government. Received: June 30, 2000 / Accepted: April 4, 2001     

Delegation, Committees, and Managers

Attempts to economize on decision-making time imply that groups of peers may delegate authority to a small committee of managers even though this means that the information and preferences of the uninvolved players are neglected. Decisions are more likely to be delegated to players with better information and more representative preferences. The possibility of ex post protests may force managers to take the preferences of others into account but may also give them incentives to ignore their private information. The argument may explain employees' willingness to let bosses decide, and thus throw some light on the theory of the firm.     

Intergenerational conflict and the political economy of higher education funding

We examine how a population's age distribution and a growing divide between the ethnic composition of older and young generations is likely to affect support for higher education funding. Using detailed survey data on voter preferences for higher education funding and precinct-level vote returns from locally-funded community college bond referenda in California, we find that older voters are significantly less supportive of higher education funding than younger voters and that support among older non-Hispanic white voters is particularly weak when those voters reside in a jurisdiction where the college-age population is more heavily Hispanic.     

Targeted political advertising and strategic behavior by uninformed voters

We consider the case where political advertising is targeted to a subset of uninformed voters and show how pressure groups, candidates, and uninformed voters interact to achieve an equilibrium outcome. The paper accomplishes the following: (1) It derives the optimal behavior of those uninformed voters who do not received targeted campaign advertising. (2) It suggests that previous results may have exaggerated the power of pressure groups and political advertising—even when there is directed advertising, any negative effect is mitigated by strategic behavior of the uninformed. (3) In the limit, pressure group donations move the outcome toward the median voter, contrary to what much of the literature on pressure groups claims.      

Voting over selective immigration policies with immigration aversion

Selective immigration policies set lower barriers to entry for skilled workers. However, simple economic intuition suggests that skilled majorities should welcome unskilled immigrants and protect skilled natives. This paper studies the voting over a selective policy in a two-country, three-factor model with skilled and unskilled labor, endogenous migration decisions, costly border enforcement and aversion to immigration. Results show that heterogeneity in capital distribution forces skilled voters to form a coalition with unskilled voters, who become pivotal. The voting outcome is therefore biased towards the preferences of the latter, and consists in a selective protectionism. Finally, immigration aversion helps to explain why skilled majorities do not bring down entry barriers against unskilled workers.     

Non-anonymous ballot aggregation: An axiomatic generalization of Approval Voting

We study axiomatically situations in which the society agrees to treat voters with different characteristics distinctly. In this setting, we propose a set of intuitive axioms and show that they jointly characterize a new class of voting procedures, called Type-weighted Approval Voting. According to this family, each voter has a strictly positive and finite weight (the weight is necessarily the same for all voters with the same characteristics) and the alternative with the highest number of weighted votes is elected. The implemented voting procedure reduces to Approval Voting in case all voters are identical or the procedure assigns the same weight to all types. Using this idea, we also obtain a new characterization of Approval Voting.     

Epistemic democracy with correlated voters

We develop a general theory of epistemic democracy in large societies, which subsumes the classical Condorcet Jury Theorem, the Wisdom of Crowds, and other similar results. We show that a suitably chosen voting rule will converge to the correct answer in the large-population limit, even if there is significant correlation amongst voters, as long as the average covariance between voters becomes small as the population becomes large. Finally, we show that these hypotheses are consistent with models where voters are correlated via a social network, or through the DeGroot model of deliberation.     

A simple voting scheme generates all binary relations on finite sets

A simple head-to-head voting scheme in which voters hold complete and transitive preferences over alternatives generates all binary relations on finite sets. The minimal number of voters required to generate a binary relation provides a measure of complexity for binary relations. Complexity so defined tells us, by how much a given binary relation fails to qualify as a total preorder.     

Designing monetary policy committees

We integrate monetary policy-making by committee into a New Keynesian model to assess the consequences of the committee׳s institutional characteristics for inflation, output, and welfare. Our analysis delivers the following results. First, we demonstrate that transparency about the committee׳s future composition is typically harmful. Second, we show that short terms for central bankers lead to effective inflation stabilization at the expense of comparably high output variability. Third, larger committees generally allow for more efficient stabilization of inflation but possibly for less efficient output stabilization. Fourth, large committees and short terms are therefore socially desirable if the weight on output stabilization in the social loss function is low. Fifth, we show that a central banker with random preferences may be preferable to a central banker who shares the preferences of society.     

Intransitive social indifference and the Arrow dilemma

This paper deals with a proposal by Frederic Schick for resolving Arrow’s dilemma of social choice. Schick challenges Arrow’s assumption that rational social indifference is transitive. It turns out, however, that even if we drop this assumption, we still face a dilemma as embarrassing as Arrow’s. Any constitution which satisfies the remaining conditions is a liberum veto oligarchy. This means a unique set of individuals carries any issue on which it is unanimous, and engenders social indifference on any issue which divides it. A formal statement and proof of this theorem follows an informal presentation of the result.