A strategy-proofness characterization of majority rule

Summary. A feasible alternative x is a strong Condorcet winner if for every other feasible alternative y there is some majority coalition that prefers x to y. Let (resp., denote the set of all profiles of linear (resp., merely asymmetric) individual preference relations for which a strong Condorcet winner exists. Majority rule is the only non-dictatorial and strategy-proof social choice rule with domain , and majority rule is the only strategy-proof rule with domain . Received: August 29, 2000; revised version: November 13, 2002 RID="*" ID="*"We are grateful to Wulf Gaertner and our two referees for insightful comments on a previous draft. Correspondence to: D. E. Campbell     

A comparison of Dodgson's method and the Borda count

Summary. In an election without a Condorcet winner, Dodgson's Method is designed to find the candidate that is “closest” to being a Condorcet winner. In this paper, we show that the winner from Dodgson's Method can occur at any position in the ranking obtained from the Borda Count, the plurality method, or any other positional voting procedure. In addition, we demonstrate that Dodgson's Method does not satisfy the Independence of Irrelevant Alternatives axiom. Received: January 12, 2001; revised version: June 7, 2001     

The Costs of Implementing the Majority Principle: The Golden Voting Rule

In a context of constitutional choice of a voting rule, this paper presents an economic analysis of scoring rules that identifies the golden voting rule under the impartial culture assumption. This golden rule depends on the weights β and (1−β) assigned to two types of costs: the cost of majority decisiveness (‘tyranny’) and the cost of the ‘erosion’ in the majority principle. Our first main result establishes that in voting contexts where the number of voters n is typically considerably larger than the number of candidates k, the golden voting rule is the inverse plurality rule for almost any positive β. Irrespective of n and k, the golden voting rule is the inverse plurality rule if β ≥ 1/2 .. This hitherto almost unnoticed rule outperforms any other scoring rule in eliminating majority decisiveness. The golden voting rule is, however, the plurality rule, the most widely used voting rule that does not allow even the slightest ‘erosion’ in the majority principle, when β=0. Our second main result establishes that for sufficiently “small size” voting bodies, the set of potential golden rules consists at most of just three rules: the plurality rule, the Borda rule and the inverse plurality rule. On the one hand, this finding provides a new rationalization to the central role the former two rules play in practice and in the voting theory literature. On the other hand, it provides further support to the inverse plurality rule; not only that it is the golden rule in voting contexts, it also belongs, together with the plurality rule and the Borda method of counts, to the “exclusive” set of potential golden voting rules in small committees. We are indebted to Jim Buchanan, Amichai Glazer, Noa Nitzan, Ken Shepsle, and an anonymous referee for their useful comments.     

A simple characterization of majority rule

Summary. Assuming an odd number of voters, E. S. Maskin recently provided a characterization of majority rule based on full transitivity. This paper characterizes majority rule with a set of axioms that includes two of Maskin's, dispenses with another, and contains weak versions of his other two axioms. It allows the number of voters to be odd or even. Received: December 23, 1998; revised version: May 10, 1999     

Rationing rule, imperfect information and equilibrium

Summary. The impact of imperfect information on the price setting behaviour of firms is analysed. Specifically, consumers support an information cost to become informed about prices. Firms are endowed with U-shaped average cost curves. If a firm does not supply more than its competitive supply as determined by its marginal cost schedule, then we show that the existence of a pure strategy equilibrium is conditional on the rationing rule employed. If uninformed consumers are served first then the monopoly price is the sole equilibrium whenever consumers' information costs are high enough. Otherwise, a pure strategy equilibrium fails to exist contrary to the results of Salop and Stiglitz (1977) or Braverman (1980) who implicitly suppose that firms supply all the demand at a given price. Received: May 17, 1999; revised version: September 15, 2000     

Candidate stability and nonbinary social choice

Summary. The requirement that a voting procedure be immune to the strategic withdrawal of a candidate for election can be formalized in different ways. Dutta, Jackson, and Le Breton (Econometrica, 2001) have recently shown that two formalizations of this candidate stability property are incompatible with some other desirable properties of voting procedures. This article shows that Grether and Plott's nonbinary generalization of Arrow's Theorem can be used to provide simple proofs of two of their impossibility theorems. Received: August 15, 2001; revised version: March 11, 2002 RID="*" ID="*" Parts of this article were previously circulated in somewhat different form in a working paper with the same title by the second author. We are grateful to Michel Le Breton and an anonymous referee for their comments. Correspondence to:J.A. Weymark     

On coalitional stability of anonymous interim mechanisms

Summary.   In a situation where agents have private information, we investigate the stability of mechanisms with respect to coalitional deviations. In the cooperative tradition, we first extend the notion of Core, taking into account the information a coalition may have when it forms and the conjectures of outsiders. This leads us to propose a family of Cores rather than a single one. Secondly, we study the stability of Core mechanisms to secession proposals in simple noncooperative games. The two different stability analyses, normative and strategic, tend to give support to the more natural extension of the Core, called Statistical Core, only in situations where some strong form of increasing returns to coalition is met. Without this property, arguments for a concept of Core that is non empty in a reasonably large class of problems are less compelling. Applications to taxation and insurance are given. Received: September 6, 1999; revised version: December 3, 1999     

The stand-alone test and decreasing serial cost sharing

Summary. The rule of decreasing serial cost sharing defined in de Frutos [1] over the class of concave cost functions may violate the important stand-alone test. Sufficient conditions for the test to be satisfied are given, in terms of individual rationality as well as coalitional stability. These conditions restrict the shape of the cost function and the distribution of demands. Received: July 29, 1999; revised version: October 4, 1999     

Revisiting Savage in a conditional world

Summary. I present an axiomatization of subjective expected utility and Bayesian updating in a conditional decision problem. This result improves our understanding of the Bayesian standard from two perspectives: 1) it uses a set of axioms which are weak and intuitive; 2) it provides a formal proof to results on the relation between dynamic consistency, expected utility and Bayesian updating which have never been explicitly proved in a fully subjective framework. Received: December 1, 2000; revised version: February 26, 2001     

Investment coordination and demand complementarities

Summary. This paper establishes necessary conditions for demand complementarity to imply investment coordination failure and explores the welfare implications of coordinated investment. Our main results caution against demand complementarities as a motive for investment coordination. We find that: 1) generally, a strict notion of complementarity (Hicks) is necessary for the existence of an investment coordination problem and 2) that when the problem does exist, coordination lowers social welfare without countervailing sectoral asymmetries. Received: June 19, 1996; revised version: December 5, 1997     

Majority cycles in a multi-dimensional setting

Summary. We consider a set of alternatives (electoral platforms, bills, etc. ...) defined as a Cartesian product of k finite discrete sets. We assume that the preferences of the individuals (voters) are marginally single-peaked and separable. The main result of this paper states that the pairwise majority relation satisfies these two properties but that it might exhibit several cycles. This result is important when related to classical problems of multi-dimensional decisions such as logrolling and vote trading. We relate our result with a continuous version of it (McKelvey, 1976). Received: March 21, 2000; revised version: April 12, 2001     

Endogenous technological change: a note on stability

Summary. This paper demonstrates that the steady-state solution of the optimal-growth problem in Romer's (1990) model of endogenous technological change is globally saddle-point stable. Surprisingly, the proof of this result is trivial. Interest in the optimal growth path is justified by the fact that there is a (unique) combination of production and R&D subsidies by means of which the optimal growth path is attained as a market equilibrium. Received: October 6, 1998; revised version: April 19, 1999     

Theorems on correspondences and stability of the core

In this note two theorems strengthening Grodal's (1971) Theorem on correspondences are proved. The first drops the convexity assumption. The second strengthens that theorem further for the case when the range is the positive orthant. In this case, the conclusion of Grodal's Theorem - the intersection of the integral with the interior of the range being open- is modified to read as the integral being a relative open subset of the positive orthant. An example is provided to show that, such a strengthening is not valid in general. This allows us to dispense with the requirment of convexity of preferences in Grodal's (1971) theorems on the closedness of the set of Pareto optimal allocations, the core, and the continuity of the core correspondence for pure exchange economies. We apply this result to show that blocking coalitions in a large economy are stable. Received: September 30, 1998; revised version: September 18, 2001 RID="*" ID="*" The author is grateful to an anonymous referee for helpful comments. The usual disclaimer applies.     

Global asymptotic stability of a competitive equilibrium with recursive preferences

Summary. This paper demonstrates global stability of a competitive equilibrium in a multi-sector model of many firms, each of which exhibits constant returns to scale technology, and of infinitely lived consumers, whose preferences are recursive but not necessarily additively separable. In the topology induced by a sup-norm, the dominant diagonal blocks condition (Araujo and Scheinkman (Econometrica 45, 1977)) allows us to apply the implicit function theorem to obtain continuity of the equilibrium path. If a stationary equilibrium is locally asymptotically stable, then the continuity of the equilibrium path and smoothness of a weight function on heterogeneous consumers imply that all equilibrium paths converge to the steady state. The dominant diagonal blocks condition is also shown to be sufficient for the local asymptotic turnpike property. Received: December 13, 1996; revised version: June 2, 1999     

Speculative trade, asset prices and investment levels

Summary. In this paper I consider a dynamically complete market model without intrinsic uncertainty. Agents' beliefs are different, but correct in the limit. Some agents are more patient than others. I show that infinitely often share prices are low and the economy stagnates. Also, infinitely often share prices are high and the economy grows. The changes from growth to stagnation and from stagnation to growth are not caused by exogenous shocks. They are caused by speculative trade among agents with different propensities to save and invest. Received: January 8, 2001; revised version: April 11, 2002 RID="*" ID="*" I thank an anonymous referee for helpful comments. I gratefully acknowledge financial support from the National Science Foundation.     

Randomization, revelation, and redistribution in a Lerner world

Summary. If total social income is fixed and a social planner is uninformed of the utility representations of different individuals, then Lerner showed that the social optimum is to equally distribute income across individuals. We show that the planner by the use of randomization can in some circumstances induce individuals to reveal information about the curvature of their utility functions and then use the information to move away from equality on average. However, whether this is optimal depends in part on unobservable beliefs of the planner. These may be viewed as an aspect of the planner's ethical judgements or as something entirely arbitrary. Received: January 11, 2000; revised version: June 26, 2001     

The evolution of debt and equity markets in economic development

Summary. As noted by Gurley and Shaw, there is a typical pattern of economic development in which the evolution of the financial system is an essential aspect of the growth process. We focus on one component of this evolution: the increasing importance of equity markets as an economy grows. We develop a growth model where capital accumulation is financed externally through a combination of debt and equity. We illustrate why equity market activity might grow – often very rapidly – as an economy develops. We also illustrate why access to equity markets may not be needed in the early stages of economic development. Received: December 30, 1997; revised version: May 26, 1998     

Utility and entropy

Summary. In this paper we study an astonishing similarity between the utility representation problem in economics and the entropy representation problem in thermodynamics. Received: May 17, 1999; revised version: October 16, 2000     

Currency restrictions,government transaction policies and currency exchange

Summary. We study how currency restrictions and government transaction policies affect the values of fiat currencies in a two country, divisible good, search model. We show that these policies can generate equilibria where both currencies circulate as medium of exchange and where currency exchange occurs between citizens of different countries. Restrictions on the internal use of foreign currency can cause the domestic currency to be relatively more valuable to domestic agents while taxes on domestic currency create an incentive for home agents to hold foreign currency. We demonstrate that some policies increase prices and lower welfare while others do the reverse. Received: September 5, 2001; revised version: March 1, 2002