Delegation and polarization of platforms in political competition

Summary. We consider a model of political competition among two ideological parties who are uncertain about the distribution of voters. The distinguishing feature of the model is that parties can delegate electoral decisions to candidates by nomination. It is shown that if the credible platform commitments of the candidates is feasible, then at least one of the parties nominates in equilibrium to a candidate who has an ideology that is more radical than the delegating party's ideology. In a variety of circumstances, this, in turn, yields a polarization of equilibrium policy choices of the candidates. It is thus argued formally here that strategic nomination of the candidates may well be one of the major reasons behind the well documented observation that the platforms associated with the political parties in two-party democracies are often surprisingly polarized. Received: January 10, 2002; revised version: May 8, 2002 RID="*" ID="*" We thank Alberto Alesina, Levent Ko?kesen, Antonio Merlo, Ronny Razin, Vijay Krishna, Alessandro Lizzeri, and seminar participants at Alicante, Columbia, Copenhagen, and NYU for helpful comments. We also thank an anonymous referee for its useful suggestions. A good fraction of this research was conducted while Ok was a visitor in the Department of Economics at University of Alicante; he thanks for the kind hospitality of this institution. We gratefully acknowledge the financial support from the Spanish Ministry of Education through grant CICYT BEC2001-0535 (Faulí-Oller) and BEC2001-0980 (Ortu?o-Ortín). Correspondence to:I. Ortu?o-Ortin     

CONSUMPTION AND PORTFOLIO POLICIES WITH INCOMPLETE MARKETS AND SHORT-SALE CONSTRAINTS IN THE FINITE-DIMENSIONAL CASE: SOME REMARKS

This paper extends He and Pearson's (1991) martingale approach to the study of optimal intertemporal consumption and portfolio policies with incomplete markets and short-sale constraints to a framework in which no assumptions are made on the price process for the securities. We show how both their characterization of the budget-feasible set and duality result can be extended to account for an unbounded set II of Arrow-Debreu state prices compatible with the arbitrage-free assumption. We also supply a (fairly general) sufficient condition for II to be bounded, as required in their setting.     

The stability and breakup of nations: a quantitative analysis

This paper quantitatively analyzes the stability and breakup of nations. The tradeoff between increasing returns in the provision of public goods and the costs of greater cultural heterogeneity mediates agents’ preferences over different geographical configurations, thus determining the likelihood of secessions and unions. After calibrating the model to Europe, we identify the regions prone to secession and the countries most likely to merge. We then estimate the implied monetary gains from EU membership. As a test of the theory, we show that the model can account for the breakup of Yugoslavia and the dynamics of its disintegration. We find that economic differences between the Yugoslav republics determined the order of disintegration, but cultural differences, though small, were key to the country’s instability. The paper also provides empirical support for the use of genetic distances as a proxy for cultural heterogeneity.     

Robust implementation under alternative information structures

In this paper we consider a model in which agents have complete information about their neighbors and, possibly, incomplete information about the rest of the environment. We consider two different informational frameworks. In the first, agents do not have priors about the relevant characteristics in the rest of the environment. In the second, agents are supposed to have priors about the unknown characteristics. We present a mechanism which implements any social choice correspondence satisfying monotonicity and no veto power in both informational settings for every possible prior thus requiring little knowledge from the point of view of the designer of the information possessed by agents about the environment. The authors wish to thank J. Canals, B. Chakravorty, P. Chander, C. Herrero, G. Orosel, D. Schmeidler, W. Thomson, W. Trockel, F. Vega, A. Villar, T. Yamato and two anonymous referees for helpful comments. The usual disclaimer applies. The first author acknowledges financial support from the Institució Valenciana d’Estudies i Investigació; L.V.I.E. and DGICYT under projects PB/88-0289 and PB/91-0756. The second author acknowledges financial support from DGICYT under project PB/90-0156. A previous version of the paper was written when authors visited (May 1991) the Institute of Mathematical Economics (Bielefeld) to which authors are grateful.     

Dynamic versus one-period completeness in event-tree security markets

We show that in event-tree security markets dynamic completeness does not coincide with one-period completeness unless the law of one price is explicitely assumed. We do so by means of a simple example of a dynamically complete market with an incomplete one-period sub-market.     

A model of endogenous political party platforms

Summary. We develop a model of endogenous party platform formation in a multidimensional policy space. Party platforms depend on the composition of the parties primary electorate. The overall social outcome is taken to be a weighted average of party platforms and individuals vote strategically. Equilibrium is defined to obtain when no group of voters can shift the social outcome in its favor by deviating and the party platforms are consistent with their electorate. We provide sufficient conditions for existence of equilibria.Received: 20 November 2002, Revised: 21 August 2003JEL Classification Numbers: D72, C62.Correspondence to: Ignacio Ortuño-OrtínWe thank A. Caplin, S. Chattopadhyay, C. Martinelli and J. D. Moreno-Ternero and two anonymous referees for helpful comments. This research started while Ortuño-Ortín was a visitor in the Department of Economics at NYU; he thanks for the kind hospitality of this institution. F. Marhuenda and I. Ortuño-Ortín gratefully acknowledge financial support from the Spanish Ministry of Science and Technology Project BEC2001-1653 and Project BEC2001-0980, respectively; A. Gomberg gratefully acknowledges the financial support from the Asociación Mexicana de Cultura.     

Arbitrage, linear programming and martingales¶in securities markets with bid-ask spreads

In a general, finite-dimensional securities market model with bid-ask spreads, we characterize absence of arbitrage opportunities both by linear programming and in terms of martingales. We first show that absence of arbitrage is equivalent to the existence of solutions to the linear programming problems that compute the minimum costs of super-replicating the feasible future cashflows. Via duality, we show that absence of arbitrage is also equivalent to the existence of underlying frictionless (UF) state-prices. We then show how to transform the UF state-prices into state-price densities, and use them to characterize absence of arbitrage opportunities in terms of existence of a securities market with zero bid-ask spreads whose price process lies inside the bid-ask spread. Finally, we argue that our results extend those of Naik (1995) and Jouini and Kallal (1995) to the case of intermediate dividend payments and positive bid-ask spreads on all assets.     

Generic Existence and Robust Nonexistence of Numéraires in Finite Dimensional Securities Markets

A numéraire is a portfolio that, if prices and dividends are denominated in its units, admits an equivalent martingale measure that transforms all gains processes into martingales. We first supply a necessary and sufficient condition for the generic existence of numéraires in a finite dimensional setting. We then characterize the arbitrage‐free prices and dividends for which the absence of numéraires survives any small perturbation preserving no arbitrage. Finally, we identify the cases when any small, but otherwise arbitrary, perturbation of prices and dividends preserves either the existence of numéraires, or their nonexistence under no arbitrage.