Certainty Independence and the Separation of Utility and Beliefs

Economists often operate under an implicit assumption that the tastes of a decision maker are quite stable, while his beliefs change with the availability of new information. We show that for a general class of preferences, a separation of a key component of tastes, the utility function, from the other components of the representation is possible only if the decision maker's preferences satisfy a mild but not completely innocuous condition, called ‘certainty independence’. We also outline the axiomatic characterization of the preferences that obtain such separation, which are a subset of the biseparable preferences.     

Macroeconomic interdependence under incomplete markets

This paper uses a two-country, flexible-price model with overlapping generations of infinitely lived households to study the role of net foreign asset dynamics in the propagation of productivity shocks. Absence of Ricardian equivalence ensures existence of a unique steady-state level of net foreign assets, to which the economy returns following temporary shocks. Model dynamics are significantly different from those of a setup in which terms of trade movements perform all the international adjustment and net foreign assets do not move. The difference relative to a complete markets economy in which net foreign asset movements play no role in shock transmission is smaller. It is amplified if the substitutability across goods rises and if shocks are permanent.     

The nature of the steady state in models of optimal growth under uncertainty

Summary. We study a one-sector stochastic optimal growth model with a representative agent. Utility is logarithmic and the production function is of the Cobb-Douglas form with capital exponent . Production is affected by a multiplicative shock taking one of two values with positive probabilities p and 1-p. It is well known that for this economy, optimal paths converge to a unique steady state, which is an invariant distribution. We are concerned with properties of this distribution. By using the theory of Iterated Function Systems, we are able to characterize such a distribution in terms of singularity versus absolute continuity as parameters and p change. We establish mutual singularity of the invariant distributions as p varies between 0 and 1 whenever . More delicate is the case . Singularity with respect to Lebesgue measure also appears for values such that . For and Peres and Solomyak (1998) have shown that the distribution is a.e. absolutely continuous. Characterization of the invariant distribution in the remaining cases is still an open question. The entire analysis is summarized through a bifurcation diagram, drawn in terms of pairs .Received: 9 April 2002, Revised: 29 October 2002, JEL Classification Numbers: C61, O41.Correspondence to: Tapan MitraThis research was partially supported by CNR (Italy) under the "Short-term mobility" program and by M.U.R.S.T. (Italy) National Group on "Nonlinear Dynamics and Stochastic Models in Economics and Finance" . We are indebted to Rabi Bhattacharya for providing us with the reference to Solomyak's (1995) paper. The present version has benefitted from comments by Mukul Majumdar and two anonymous referees.     

Judicial Branch, Checks and Balances and Political Accountability

This paper attempts to combine the political economics models on separation of powers between the legislature and the executive with public choice theories on the behavior of the judicial branch. We obtain a model of political accountability and checks and balances with up to three government branches: the executive, the legislature and the judiciary. We conclude that an independent judiciary improves the political accountability of democratic systems relative to the political economics models with two government branches. An accommodating judiciary, however, changes the distribution of political rents without improving accountability.     

A Model of the Representation of Interests in a Compound Democracy

This paper provides a model of democratic government as a compound of independent elective and non elective centers of power that compete in fostering the demands of voters and of interest groups. The analysis describes how interests of voters and of pressure groups are represented and under what conditions the compound democracy is more responsive to voters' or to interest groups' demands. These conditions are shown to depend on the center of power's relative opportunity costs at serving a plurality of interests and on the severeness of informational asymmetries between voters and interest groups.     

Employment changes, the structure of adjustment costs, and plant size

In this paper, we analyze the pattern of employment adjustment using a rich panel of Norwegian plants. The data suggest that the frequency of episodes of zero net employment changes is inversely related to plant size. We develop and estimate a simple “q” model of labor demand, allowing for the presence of fixed, linear and quadratic components of adjustment costs. The econometric evidence supports the existence of purely fixed components, unrelated to plant size. As a result, the range of inaction is wider for smaller plants. The quadratic component of costs is also always important. In most specifications fixed costs are higher for employment contractions. The quadratic component is higher during employment contractions compared to expansions for small plants, while this is not true for larger plants.     

A characterization for solutions of stochastic discrete time optimization models

A notion of finitely optimal plan for intertemporal optimization problems as a necessary condition for optimality is introduced. Under interiority of a feasible plan and differentiability of the return function, such a plan satisfies the stochastic analogue of deterministicEuler-Lagrange conditions, which become also sufficient conditions under concavity of the return function. Then, under more general assumptions, a sufficient criterion of optimality based on competitive plans supported by price systems and transversality conditions is discussed. Differently from the current literature, no restrictive hypotheses on the probability measure of the random shocks are assumed.

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Sommario Nella prima parte del lavoro si studiano le soluzioni dettefinitamente ottime che costituiscono una condizione necessaria per l'ottimalità di un piano ammissibile . Sotto ipotesi di interiorità del piano ammissibile e di differenziabilità della funzione obiettivo uniperiodaleF, vengono formulate le condizioni necessarie diEuler-Lagrange in ambito stocastico; aggiungendo l'ulteriore ipotesi di concavità perF, tali condizioni diventano anche sufficienti per l'ottimalità finita.La teoria viene poi estesa al caso sopradifferenziabile ottenendo una generalizzazione delle condizioni di Euler-Lagrange stocastiche che consente di individuare i piani finitamente ottimi mediante la nozione dicompetitività, ovvero supportabilità di un sistema di prezzi aleatori. Con una condizione di trasversalità all'infinito, la competitività diventa condizione sufficiente anche per l'ottimalità propria (cioè non solo finita).La peculiarità della presente trattazione è che tali condizioni sono formulate sotto ipotesi molto generali per quanto riguarda il processo degli shocks esogeni.

     

Economic theory and ideology inMarx and modern economic analysis Giovanni A. Caravale,editor Edward Elgar, 1991, 512 pp.

The collection of essays edited by Giovanni Caravale has the explicit aim of letting the reader know the principal positions that have characterized the long-lasting debate in the themes of Marxian economics. In particular, the book is concerned with the contributions of those authors who recognize the relevance of Piero Sraffa's analysis for the interpretation of Marxian economic thought, showing that, even among these authors, opinions on the topic are deeply different. The book consists of two volumes: the first one, "Values, Prices and Exploitation," deals with the main theme of Marxian value theory, while the second, "The Future of Capitalism and the History of Thought," deals with discussion of the law of the falling rate of profit and of the role of Marx's theory in the history of economic thought.     

Some reflections on past and future of nonlinear dynamics in economics and finance

This paper offers an overview of the literature on the economic and financial applications of theory of nonlinear dynamics, especially bifurcation theory. After a short introductory discussion of the first nonlinear dynamic models in social sciences and the economic relevance of the zoo of bifurcations and complicated dynamics that such models can generate, we present an overview of the literature on nonlinear dynamic models in the areas of underdevelopment, environmental poverty traps, the management of common goods, industrial organization and financial markets. The review of the literature is enriched by reflections and ideas for future research.