Arrow's original proof of his impossibility theorem proceeded in two steps: showing the existence of a decisive voter, and then showing that a decisive voter is a dictator. Barbera replaced the decisive voter with the weaker notion of a pivotal voter, thereby shortening the first step, but...

A decision maker has to choose one of several random variables, with uncertainty known distributions. As a Bayesian she behaves as if she knew the distributions. In his paper we suggest an axiomatic derivation of these (subjective) distributions, which is much more economical than the...

This introduces the symposium on judgment aggregation. The theory of judgment ag­gregation asks how several individuals' judgments on some logically connected propo­sitions can be aggregated into consistent collective judgments. The aim of this intro­duction is to show how ideas from the...

A decision maker faces a decision problem, or a game against nature. For each probability distribution over the state of the world (nature's strategies), she has a weak order over her acts (pure strategies). We formulate conditions on these weak orders guaranteeing that they can be jointly...

The discounted-utilitarian social welfare function (DU) is used by the great majority of researchers studying intergenerational resource allocation in the presence of climate change (e.g., W. Nordhaus, M. Weitzman, N. Stern, and P. Dasgupta). I present three justifications for using DU: (1) the...

Attainment of rational expectations equilibria in asset markets calls for the price system to disseminate traders’ private information to others. It is known that markets populated by asymmetrically-informed profit-motivated human traders can converge to rational expectations equilibria. This...

Attainment of rational expectations equilibria in asset markets calls for the price system to disseminate agents’ private information to others. Markets populated by human agents are known to be capable of converging to rational expectations equilibria. This paper reports comparable market...

Behavioral economics has demonstrated systematic decision-making biases in both lab and field data. But are these biases learned or innate? We investigate this question using experiments on a novel set of subjects — capuchin monkeys. By introducing a fiat currency and trade to a capuchin...

A predictor is asked to rank eventualities according to their plausibility, based on past cases. We assume that she can form a ranking given any memory that consists of finitely many past cases. Mild consistency requirements on these rankings imply that they have a numerical representation via a...

We describe conditions for the existence of a stationary Markovian equilibrium when total production or total endowment is a random variable. Apart from regularity assumptions, there are two crucial conditions: (i) low information -- agents are ignorant of both total endowment and their own...