Rich behavioral biases, mistakes and limits on rational decision-making are often thought to make equilibrium analysis much more intractable. We establish that this is not the case in the context of one-sector growth models such as Ramsey-Cass-Koopmans or Bewley-Aiyagari models. We break down the response of the economy to a change in the environment or policy into two parts: the direct response at the given (pre-tax) prices, and the equilibrium response which plays out as prices change. Our main result demonstrates that under weak regularity conditions, regardless of the details of behavioral preferences, mistakes and constraints on decision-making, the long-run equilibrium will involve a greater capital-labor ratio if and only if the direct response (from the corresponding consumption-saving model) involves an increase in aggregate savings. One implication of this result is that, from a qualitative point of view, behavioral biases matter for long-run equilibrium if and only if they change the direction of the direct response. We provide detailed illustrations of how this result can be applied and generates new insights using models of misperceptions, self-control and temptation, and naive and sophisticated quasi-hyperbolic discounting.

Distributional comparative statics is the study of how individual decisions and equilibrium outcomes vary with changes in the distribution of economic parameters (income, wealth, productivity, information, etc.). This article develops new tools to address such issues and illustrates their usefulness in applications. The central development is a condition called quasi-concave differences, which implies concavity of the policy function in optimization problems without imposing differentiability or quasi-concavity conditions. The general take-away is that many distributional questions in economics which cannot be solved by direct calculations or the implicit function theorem, can be addressed easily with this article’s methods. Several applications demonstrate this: the article shows how increased uncertainty affects the set of equilibria in Bayesian games; it shows how increased dispersion of productivities affects output in the model of Melitz (2003); and it generalizes Carroll and Kimball (1996)’s result on concave consumption functions to the Aiyagari (1994) setting with borrowing constraints.

© The Author 2015. Committee voting has mostly been investigated from the perspective of the standard Baron-Ferejohn model of bargaining over the division of a pie, in which bargaining ends as soon as the committee reaches an agreement. In standing committees, however, existing agreements can be amended. This article studies an extension of the Baron-Ferejohn framework to a model with an evolving default that reflects this important feature of policymaking in standing committees: In each of an infinite number of periods, the ongoing default can be amended to a new policy (which is, in turn, the default for the next period). The model provides a number of quite different predictions. (i) From a positive perspective, the key distinction turns on whether the quota is less than unanimity. In that case, patient enough players waste substantial shares of the pie each period and the size principle fails in some pure strategy Markov perfect equilibria. In contrast, the unique Markov perfect equilibrium payoffs in a unanimity committee coincide with those in the corresponding Baron-Ferejohn framework. (ii) If players have heterogeneous discount factors then a large class of subgame perfect equilibria (including all Markov perfect equilibria) are inefficient.