The dynamics of risk-sensitive allocations

This paper describes Pareto optimal allocations when agents have risk-sensitive preferences as formulated by Hansen and Sargent (IEEE Trans. Automat. Control 40(5) (1995) 968-971). Necessary and sufficient conditions are given for the existence and stability of steady states at which Pareto weights are time-invariant. When all agents are risk-sensitive with the same power reward function there is a unique interior steady state which is stable when the power is positive and unstable when the power is negative. When there is at least one agent with time-additive preferences eventually all risk-sensitive agents have zero Pareto weights.     

Efficient strategy-proof exchange and minimum consumption guarantees

For exchange economies with classical economic preferences, it is shown that any strategy-proof social choice function that selects Pareto optimal outcomes cannot guarantee everyone a consumption bundle bounded away from the origin. This result demonstrates that there is a fundamental conflict between efficiency and distributional goals in exchange economies if the social choice rule is required to be strategy-proof.     

Efficiency and equilibrium when preferences are time-inconsistent

We consider an exchange economy with time-inconsistent consumers whose preferences are additively separable. If consumers have identical discount factors, then allocations that are Pareto efficient at the initial date are also renegotiation-proof. In an economy with a sequence of markets, competitive equilibria are Pareto efficient in this sense, and for generic endowments, only if preferences are locally homothetic.     

Information-constrained optima with retrading: An externality and its market-based solution

This paper studies the efficiency of competitive equilibria in environments with a moral hazard problem and unobserved states, both with retrading in ex post spot markets. The interaction between private information problems and the possibility of retrade creates an externality, unless preferences have special, restrictive properties. The externality is internalized by allowing agents to contract ex ante on market fundamentals determining the spot price or interest rate, over and above contracting on actions and outputs. Then competitive equilibria are equivalent with the appropriate notion of constrained Pareto optimality. Examples show that it is possible to have multiple market fundamentals or price-islands, created endogenously in equilibrium.     

Arrovian aggregation in economic environments: how much should we know about indifference surfaces?

Arrow's celebrated theorem of social choice shows that the aggregation of individual preferences into a social ordering cannot make the ranking of any pair of alternatives depend only on individual preferences over that pair, unless the fundamental weak Pareto and non-dictatorship principles are violated. In the standard model of division of commodities, we investigate how much information about indifference surfaces is needed to construct social ordering functions satisfying the weak Pareto principle and anonymity. We show that local information such as marginal rates of substitution or the shapes “within the Edgeworth box” is not enough, and knowledge of substantially non-local information is necessary.     

On the interaction between risk sharing and capital accumulation in a stochastic OLG model with production

We analyze the interaction between risk sharing and capital accumulation in a stochastic OLG model with production. We give a complete characterization of interim Pareto optimal competitive equilibrium allocations. Furthermore, we provide tests of Pareto optimality/suboptimality based on (risky) rates of return only.     

Utilitarianism for infinite utility streams: A new welfare criterion and its axiomatic characterization

A definition of a utilitarian social welfare relation (SWR) for infinite utility streams is proposed. Such a relation is characterized in terms of the Pareto, Anonymity and Partial Unit Comparability Axioms. The merits of the utilitarian SWR, relative to the more restrictive SWR induced by the overtaking criterion, are examined.     

On the impossibility of complete Non-Interference in Paretian social judgements

We study a principle of ‘Non-Interference’ in social welfare judgements. Non-Interference captures aspects of liberal approaches (particularly a Millian approach) to social decision making. In its full generality, Non-Interference produces an impossibility result: together with Weak Pareto Optimality, it implies that a social welfare ordering must be dictatorial. However, interesting restricted versions of Non-Interference are compatible with standard social welfare orderings.     

A characterization of consistent collective choice rules

We characterize a class of collective choice rules such that collective preference relations are consistent. Consistency is a weakening of transitivity and a strengthening of acyclicity requiring that there be no cycles with at least one strict preference, which excludes the possibility of a “money pump.” The properties of collective choice rules used in our characterization are unrestricted domain, strong Pareto, anonymity and neutrality. If there are at most as many individuals as there are alternatives, the axioms provide an alternative characterization of the Pareto rule. If there are more individuals than alternatives, however, further rules become available.     

Social welfare orderings for ratio-scale measurable utilities

Summary. This article characterizes all of the continuous social welfare orderings which satisfy the Weak (resp. Strong) Pareto principle when utilities are ratio-scale measurable. With Weak Pareto, on both the nonnegative and positive orthants the social welfare ordering must be representable by a weakly increasing Cobb-Douglas social welfare function while on the whole Euclidean space the social welfare ordering must be strongly dictatorial. With Strong Pareto, on the positive orthant the social welfare ordering must be representable by a strictly increasing Cobb-Douglas social welfare function but on the other two domains an impossibility theorem is obtained. Received: July 31, 1995; revised version August 7, 1996     

Idiosyncratic risk and financial policy

In economies subject to uninsurable idiosyncratic risks, competitive equilibrium allocations are constrained inefficient: reallocations of assets support Pareto superior allocations. This is the case even if the asset market for the allocation of aggregate risks is complete.     

Eliciting information from a committee

The paper addresses the mechanism design problem of eliciting truthful information from a committee of informed experts who collude in their information disclosure strategies. It is shown that under fairly general conditions full information disclosure is possible if and only if the induced outcome is Pareto undominated for the committee members.     

A comparison of city size distributions for China and India from 1950 to 2010

We examine the distributions of Chinese and Indian city sizes for seven decades (1950s to 2010s) using lognormal, Pareto, and general Pareto distributions. We ascertain which distribution fits the data and how the city size distributions change during these periods. The Chinese city size distribution is represented by lognormal in the early periods (1950–1990) and by Pareto in 2010, but is not characterized by Zipf, which could be attributed to Chinese government’s restrictions of migration from rural to urban areas and the one-child policy. In contrast, the Indian city size distribution transitions from lognormal in the earlier periods to Zipf in the later periods.     

Are rich people smarter?

We formulate a general stochastic process of wealth accumulation by capital investment and analyze the conditions required to ensure convergence to the empirically observed Pareto wealth distribution. While homogeneous investment talent leads to the Pareto distribution under very general conditions, even a mild degree of differential investment talent results in a non-Pareto wealth distribution. This finding suggests that chance, rather than differential investment talent, is the dominant factor in the process of wealth accumulation by financial investment. Our findings conform with market efficiency and may have implications regarding the origins, the economic significance, and the social desirability of wealth inequality at the high-wealth range.     

FARSIGHTED COALITIONAL STABILITY OF A PRICE LEADERSHIP CARTEL

This paper analyzes the farsighted behaviour of firms that form a dominant price leadership cartel. We consider stability concepts such as the farsighted core, the farsighted stable sets, and the largest consistent set. We show that: (i) the farsighted core is either an empty set or a singleton set of the grand cartel; (ii) any Pareto efficient cartel is itself a farsighted stable set; and (iii) the set of cartels in which fringe firms enjoy higher profits than the firms in the minimal Pareto efficient cartel is the largest consistent set.     

An efficiency theorem for incompletely known preferences

There are n agents who have von Neumann-Morgenstern utility functions on a finite set of alternatives A. Each agent i's utility function is known to lie in the nonempty, convex, relatively open set Ui. Suppose L is a lottery on A that is undominated, meaning that there is no other lottery that is guaranteed to Pareto dominate L no matter what the true utility functions are. Then, there exist utility functions ui∈Ui for which L is Pareto efficient. This result includes the ordinal efficiency welfare theorem as a special case.     

Intertemporal market division:: A case of alternating monopoly

In this paper, we report on an equilibrium with market dominance that exists in a simple two-firm model that features neither entry barriers nor sophisticated punishment strategies. This equilibrium induces an intertemporal market division in which the two firms alternate as monopolists - despite the fact that the model also sustains a Cournot duopoly. Even when initially both firms are active in the market, the alternating monopoly reveals itself rather quickly. Moreover, it Pareto dominates the Cournot equilibrium - as it is close to the cartel outcome. Several examples of what well may be such alternating monopolies are presented.     

Ambiguity and perceived coordination in a global game

In a global game, larger ambiguity is shown to decrease the amount of coordination each player perceives. Consequently, small uncertainty tends to select the Pareto dominated equilibrium of the game without uncertainty. Implications for models of financial crises are drawn.     

Electing a representative committee by approval ballot: An impossibility result

We consider methods of electing a fixed number of candidates, greater than one, by approval ballot. We define a representativeness property and a Pareto property and show that these jointly imply manipulability.     

Distribution of wealth and incomplete markets: Theory and empirical evidence

This paper analyses the equilibrium distribution of wealth in an economy where firms’ productivities are subject to idiosyncratic shocks, returns on factors are determined in competitive markets, households have linear consumption functions and government imposes taxes on capital and labour incomes and equally redistributes the collected resources to households. The equilibrium distribution of wealth is explicitly calculated and its shape crucially depends on market incompleteness. With incomplete markets it follows a Paretian law in the top tail and the Pareto exponent depends on the saving rate, on the net return on capital, on the growth rate of population, and on portfolio diversification. The characteristics of the labour market crucially affects the bottom tail, but not the upper tail of the distribution of wealth in the case of completely decentralized labour market. The analysis also suggests a positive relationship between growth and wealth inequality. The theoretical predictions find a corroboration in the empirical evidence of United States in the period 1989-2004.