Sayantan Ghosal

Farsighted network formation

This paper studies a model of dynamic network formation when individuals are farsighted : players evaluate the desirability of a “current” move in terms of its consequences on the entire discounted stream of payoffs. We define a concept of equilibrium which takes into account far-sighted behavior of agents and allows for limited cooperation amongst agents. We show that an equilibrium process of network formation exists. We also show that there are network structures in which no equilibrium strategy profile can sustain efficient networks. We then provide sufficient conditions under which the equilibrium process will yield efficient outcomes.

From the Counting House to the Modern Office: Explaining Anglo-American Productivity Differences in Services, 1870–1990

The United States overtook Britain in comparative aggregate productivity levels primarily as a result of trends in services rather than trends in industry. This occurred during the transition from customized, low-volume, high-margin business organized on the basis of networks to standardized, high-volume, low-margin business with hierarchical management from the 1870s. This transformation from the counting house to the modern office was dependent on technologies that improved communications and information processing. The technologies were slower to diffuse in Britain as a result of lower levels of education and stronger labor-force resistance to intensification.

Costly voting when both information and preferences differ: is turnout too high or too low?

We study a model of costly voting over two alternatives, where agents’ preferences are determined by both (i) a private preference in favour of one alternative e.g. candidates’ policies, and (ii) heterogeneous information in the form of noisy signals about a commonly valued state of the world e.g. candidate competence. We show that depending on the level of the personal bias (weight on private preference), voting is either according to private preferences or according to signals. When voting takes place according to private preferences, there is an unique equilibrium with inefficiently high turnout. In contrast, when voting takes place according to signals, turnout is locally too low. Multiple Pareto-ranked voting equilibria may exist and in particular, compulsory voting may Pareto dominate voluntary voting. Moreover, an increase in personal bias can cause turnout to rise or fall, and an increase in the accuracy of information may cause a switch to voting on the basis of signals and thus lower turnout, even though it increases welfare.

Cournot-Walras equilibrium as a subgame perfect equilibrium

In this paper, we investigate the problem of the strategic foundation of the Cournot–Walras equilibrium approach. To this end, we respecify à la Cournot–Walras the mixed version of a model of simultaneous, noncooperative exchange, originally proposed by Lloyd S. Shapley. We show, through an example, that the set of the Cournot–Walras equilibrium allocations of this respecification does not coincide with the set of the Cournot–Nash equilibrium allocations of the mixed version of the original Shapley’s model. As the nonequivalence, in a one-stage setting, can be explained by the intrinsic two-stage nature of the Cournot–Walras equilibrium concept, we are led to consider a further reformulation of the Shapley’s model as a two-stage game, where the atoms move in the first stage and the atomless sector moves in the second stage. Our main result shows that the set of the Cournot–Walras equilibrium allocations coincides with a specific set of subgame perfect equilibrium allocations of this two-stage game, which we call the set of the Pseudo–Markov perfect equilibrium allocations.

Retrading in Market Games

When agents are not price takers, they typically cannot obtain an efficient reallocation of resources in one round of trade. This paper presents a noncooperative model of imperfect competition where agents can retrade allocations,consistent with the Edgeworth’s idea of recontracting. We show that there are allocations on the Pareto frontier that can be approximated arbitrarily closely when trade is myopic, i.e., when agents play a static Nash equilibrium at every round of retrading. We then show that the converging sequence of allocations generated by myopic retrading can also be supported along some retrade-proof Subgame Perfect Equilibrium path when traders anticipate future rounds of retrading.

Behavioral Decisions and Welfare

We study decision problems where (a) preference parameters are defined to include psychological/moral considerations and (b) there is a feedback effect from chosen actions to preference parameters. In a standard decision problem the chosen action is required to be optimal when the feedback effect from actions to preference parameters is fully taken into account. In a behavioural decision problem the chosen action is optimal taking preference parameters as given although chosen actions and preference parameters are required to be mutually consistent. Our framework unifes seemingly disconnected papers in the literature. We characterize the conditions under which behavioural and standard decisions problems are indistinguishable : in smooth settings, the two decision problems are generically distinguishable. We show that in general, revealed preferences cannot be used for making welfare judgements and we characterize the conditions under which they can inform welfare analysis. We provide an existence result for the case of incomplete preferences. We suggest novel implications for policy and welfare analysis.

Democracy, Collective Action and Intra-elite Conflict

We analyze a model where there is uncertainty about the future power of two ex-ante symmetric elites to appropriate surplus, and ex-ante surplus sharing agreements are not binding. We show that in an oligarchy, the stronger elite appropriates the entire available surplus, whereas a democracy results in a more balanced surplus allocation between the two elites. In a democracy, the newly enfranchised non-elite organize to act collectively, so that the weaker elite can credibly threaten to form a coalition with the organized non-elite against the stronger elite. Such a threat ensures that the more balanced surplus sharing proposal chosen by majority voting is renegotiation-proof. Therefore, sufficiently risk-averse elites unanimously choose democracy as a form of insurance against future imbalances in relative power. We emphasize that franchise extension to, and low cost of organizing collective political activity for, the non-elite are both necessary features of a democracy. Our formal analysis can account for the stylized facts that emerge from a comparative analysis of Indian and Western European democracies.

Local coordination and market equilibria

We reformulate the local stability analysis of market equilibria in a competitive market as a local coordination problem in a market game, where the map associating market prices to best-responses of all traders is common knowledge and well-defined both in and out of equilibrium. Initial expectations over market variables differ from their equilibrium values and are not common knowledge. This results in a coordination problem as traders use the structure of the market game to converge back to equilibrium. We analyse a simultaneous move and a sequential move version of the market game and explore the link with local rationalizability.

Decisions with Endogenous Frames

We develop a model of decision-making with endogenous frames and contrast the normative implications of our model to those of choice theoretic models in which observed choices are determined by exogenous frames or ancillary conditions. We argue that, frames, though they may be taken as given by the decision-maker at the point when choices are made, matter for both welfare and policy purposes.

On existence of undominated pure strategy Nash equilibria in anonymous nonatomic games: a generalization

AbstractIn this paper, we generalize the exitence result for pure strategy Nash equilibria in anonymous nonatomic games. By working directly on integrals of pure strategies, we also generalize, for the same class of games, the existence result for undominated pure strategy Nash equilibria even though, in general, the set of pure strategy Nash equilibria may fail to be weakly compact.