L’article met en avant la difficulté de percevoir où Ph. Van Parijs situe la limite entre le modèle économique — susceptible d’expliquer de nombreux phénomènes sociaux, mais pas tous — et les modèles evolutionnaires. Parfois il semble soutenir que les modèles evolutionnaires sont nécessaires pour expliquer des situations où les individus agissent sans la moindre délibération préalable. Mais à d’autres endroits il semble que ces modèles soient supposés être à même d’expliquer les «données» du modèle économique, à savoir les préférences et les croyances. Le mecanisme evolutionnaire de renforcement est analysée en détail dans l’article dans l’intention de déterminer quelle est l’interpretation correcte. Il apparait que la seconde interpretation est la plus plausible. On montre en effet que le mécanisme evolutionnaire est à la base de l’explication de la convergence des croyances des individus à condition qu’ils aient certaines preférences. Le renforcement ne présuppose pas, mais pourrait expliquer, des comportements obéissant à des règles non délibératives. On observe également que ce même mécanisme de renforcement, ainsi compris, est implicitement supposé être à l’oeuvre dans de nombreuses tentatives de développement de modèles evolutionnaires émanant d’économistes.

Many practical decisions, in medicine and elsewhere, alter the lengths of people’s lives; many affect the number of people who are born; and many do both. Decision makers need to attach a value to changes of these sorts. In the past the value of prolonging life and the value of changes in population have generally been treated separately. This paper explains the need for an integrated treatment: a theory of the value of living. In one sense, prolonging a life and bringing into existence an extra person are alternative ways of doing the same thing: both bring it about that a period of life is lived that otherwise would not have been lived. But there is also a vital difference: in one case the extra period of life comes to someone who exists already; in the other it comes to a new person. The paper discusses a number of principles that might be used in developing an integrated theory of the value of living.

This paper analyses the impact of input uncertainty on labour demand. An ARCH-M model is incorporated into an error-correction framework which allows to model both short- and long-run labour demand. The conditional variance of unexpected output changes serves as a proxy for demand uncertainty. The output and employment equations are estimated simultaneously for the West-German manufacturing sector.

Van Parijs démontre que certains schémas d’explication fonctionnalistes ou évolutionnistes (par renforcement/accommodement) sont compatibles avec le schéma d’explication économique (fondements microéconomiques de la macroéconomie), à condition d’affaiblir la rationalité individuelle. Curieusement, Van Parijs refuse ce pas en avant vers le « Réalisme Cognitif » dans le cas du modèle économique, pour lequel il continue de recommander la conception optimisatrice de la rationalité individuelle. Cette contradiction a deux effets: elle coupe Van Parijs des interrogations actuelles sur les institutions, et elle enferme son travail dans la perspective ancienne de Friedman (1953).

This paper aims at investigating the determinants of self- employment within a structural model of discrete choice under uncertainty. The basic idea of our approach centres around Knight's (1921) famous view of entrepreneurs receiving risk-adjusted income that has to exceed the income of employees because of the greater variance of the income stream. Unlike previous econometric approaches, which use reduced form specifications that are more or less based on ad-hoc reasoning, we derive a choice equation of which the parameters have a clear interpretation in terms of the parameters of the underlying von Neumann-Morgenstern utility function. The specification allows to identify how the difference in income risk between wage-employment and self- employment enters the choice equation without approximating the risk difference via a reduced form specification. The model is estimated using a random effects panel probit estimator with unrestricted autocorrelation structure. Estimates are based on a balanced panel of 1,926 working men selected from the West German Socio-Economic Panel 1984 to 1989.

Le modèle économique et ses rivaux accorde une importance centrale à la distinction entre un paradigme économique ou rationaliste, défini par l’agrégation d’actions rationnelles, et un paradigme évolutionnaire défini par un processus de renforcement. Vromen soutient que cette distinction est intenable, tandis que Favereau suggère que le paradigme rationaliste, tel qu’il est décrit, correspond à une étape friedmanienne de la théorie économique, qui arrive maintenant à son terme. Dans cette réponse, je soutiens que la distribution tient la route, et que le modèle rationaliste n’est pas solidaire de la méthodologie friedmanienne, mais que les deux défis indiquent d’intéressants nouveaux développements du projet de dégager la structure profonde des sciences sociales en général, et de la science économique en particulier, projet auquel « Le Modèle économique et ces rivaux » s’est efforcé de continuer.

The observed fact that firms invest even if capacities are not fully employed does not fit into most standard formalizations of optimal firm behaviour. In this paper, the q investment approach is adapted to an imperfect competitive economy where the representative firm is assumed to face demand uncertainty. Nominal rigidities and short-run factor complementarity are imposed as sufficient conditions to allow for the coexistence of investment and excess capacity. Since capacities are underemployed, marginal q is shown to diverge from average q. Finally, excess capacity subsists at steady state being more than a short-run phenomena.

As has been found in previous studies, the labor market performance of individuals is often affected by demographic determinants like cohort size, age, marriage status and family size. While most of this analysis was studied for earnings, the paper investigates the issue for labor mobility. Mobility is measured here by the number of new employers and the frequency of unemployment of an individual in a particular period. Given the discrete nature of the data, the ordinal probit model and the censored Poisson as the censored negative binomial model was estimated. Since the choice of the statistical model is not clear a priori, various model comparisons are carried out and some new pseudo-R2 measures are proposed and used in the analysis. Results indicate that demographic determinants matter for labor mobility.

The paper discusses the relationship between two problems, namely: (i) assigning a value to reduction in death probabilities, i.e. defining a « value of life », and (ii) assigning a value to changes in population, i.e. defining guidelines for the ethics and economics of population. While, for Broome, “in one sense, prolonging a person’s life and adding a new person to the world are alternative ways of doing the same things”, this paper argues that the two problems are quite distinct, in the sense that a precise answer to the first provides no guide live at all for second, and conversely. There is no inconsinstency in providing safety according to a high “value of life” while giving population growth a negative value. But there is a methodological link: both problemes have a public choice dimension, and can therefore be approached along parallel methodological lines. With respect to the economics and ethics of population, the paper offers some defense of the Pareto criterion among the living, and comments on the practice and theory of social choise.

Lately several authors have tried to explain the emergence of Stackelberg leadership as an endogenous feature of duopoly models. This article describes two models where assumptions of incomplete information about the rival firm’s marginal cost of production creates incentives for duopolistic firms to end up in a sequential choice situation. In the first model the duopolists can commit themselves to be a Stackelberg leader or follower at the time when they know the distributions, but not the actual values, of their own and the rival’s cost. The central result from this model is that under quantity (but not price) competition the duopolists may agree on who should be the leader and who should be the follower. In the second model the firms cannot commit to a specific role. In the quantity setting version of this model they must decide both when and how much to produce. It turns out that there can never be an equilibrium where they both always produce in the same period. However, there are equilibria where one firm produces in the first period and the other in the second, i.e. Stackelberg-type equilibria. Similar results are found in a price setting version of the model.

According to the “public capital hypothesis” public investment crowds in private investment by increasing the rate of return to private capital. The present paper uses an extended cost function with public capital included as an unpaid fixed factor of production to examine the impact public capital has on the private economy. Using a panel of four highly aggregated sectors of the West German Economy, it is shown, that the provision of public capital raises the demand for private capital, as suggested by the public capital hypothesis. In addition, it is shown that public infrastructure capital contributes to the productivity of the private economy.

This paper presents an extension of Chamberlain's approach to modelling correlated random effects in a dichotomous model estimated on panel data. The extension consists in relaxing the arbitrary normality assumption made on all error terms and on specifying instead a SNP distribution for the composite error term resulting in each wave from Chamberlain's treatment of correlated random effects. An application to a panel of 1325 German firms illustrates the feasibility of the approach.

La possibilité selon laquelle la flexibilité des prix et des salaires peut augmenter l’ampleur des fluctuations cycliques a été avancée. Si ces grandeurs nominales sont flexibles, en cas de récession la baisse de prix pourrait faire monter le taux d’intérêt réel, freinant ainsi encore davantage la demande, et aggravant la crise. On rejoint ainsi la théorie de la “debt deflation”: dans les récessions, la baisse de prix accroît la valeur réelle de l’endettement, dégrade la situation financière des agents emprunteurs et concourt au recul de l’activité. Cette théorie pourrait retrouver une actualité aujourd'hui, en particulier dans des pays comme la France, en raison de la réduction des rigidités qui affectaient les marchés du travail. Nous l’analysons à l’aide d’un modèle simple faisant intervenir le mode de formation des salaires, les anticipations d’inflation, diverses possibilités de distorsions nominales ou rigidités, et plusieurs chocs aléatoires affectant l’économie.

This paper demonstrates that the level of autocorrelation in the market index returns of the Brussels Stock Exchange depends on the number of securities which make up the index as well as their price adjustment delay. It also shows that the value of the systematic risk depends on both the choice of an index and the length of the differencing interval used to calculate the returns. Furthermore it highlights the fact that autocorrelation coefficients and systematic risk coefficients also exhibit seasonal fluctuations.

This paper outlines a methodology to identify the preference parameters that characterize household behaviour over the life-cycle, through the specification and estimation of a model of individual behaviour. The focus of this research is directed towards commodity demands, female labour supply and the intertemporal allocation of lifetime wealth. Empirical estimates of the parameters of interest are reported at the end of this paper.

Within the context of a macroeconometric rationing model the importance of rationing for international trade flows is investigated. The model describes rationing barriers on domestic and foreign markets which lead to spillover effects on domestic imports and exports. The novelties of this study are the more detailed analysis of the dynamics of international trade flows and the use of business survey data as proxies for rationing barriers. The model is estimated for Germany. As a result rationing does influence trade flows to a non-negligible extent. Moreover, business survey data are a useful indicator for rationing but they do not outperform other proxies such as the degree of capacity utilization.