Publications

Le projet de Philippe Grill est d’enquêter sur les origines et les fondements des doctrines et théories relatives aux libertés et à l’égalité. Son approche est proprement philosophico-économique, au sens où elle s’appuie sur l’une et l’autre discipline. Cette exploration conceptuelle des théories économiques et philosophiques, des hypothèses qui les fondent, des notions qui les irriguent, ou encore des masses de données empiriques aux interprétations multiples, voire contradictoires, se révèle cruciale car c’est à partir de ces doctrines et théories que sont conçues et promues les organisations sociales et les politiques publiques qui déterminent « dans quel monde on vit », en décrétant le possible et l’impossible en ces domaines. L’ouvrage contribue ainsi pleinement aux débats actuels d’éthique sociale en fournissant les moyens de définir ce que pourrait être une organisation sociale « humaniste ».
En effet, si l’on veut changer le monde, il faut le comprendre… Sereinement, pédagogiquement, c’est notamment à cette compré­hen­sion maximale que nous invite Philippe Grill. La somme encyclopédique qu’il nous propose déploie le panorama d’une philosophie économique où sont convoqués les savoirs contemporains issus de nombreuses disciplines (outre les sciences économiques bien sûr, les autres sciences sociales, la logique, l’épistémologie, les sciences cognitives, les neurosciences, la biologie de l’évolution, etc., ainsi que les engagements ontologiques des nombreux penseurs que l’ouvrage étudie). Ici, point de simple juxtaposition de disciplines, mais une architecture des connaissances qui veut montrer que les conceptions idoines sont nécessairement connexes si l’on entend démêler l’écheveau d’un homo œconomicus authentique, renversant le modèle factice que rabâchent les propagandistes de vulgates économiques outrancièrement simplistes et irréalistes. Ainsi, ce livre est un puissant levier de ce mouvement salutaire. Moins

We present an inexact proximal point algorithm using quasi distances to solve a minimization problem in the Euclidean space. This algorithm is motivated by the proximal methods introduced by Attouch et al., section 4, (Math Program Ser A, 137: 91-129, 2013) and Solodov and Svaiter (Set Valued Anal 7:323-345, 1999). In contrast, in this paper we consider quasi distances, arbitrary (non necessary smooth) objective functions, scalar errors in each objective regularized approximation and vectorial errors on the residual of the regularized critical point, that is, we have an error on the optimality condition of the proximal subproblem at the new point. We obtain, under a coercivity assumption of the objective function, that all accumulation points of the sequence generated by the algorithm are critical points (minimizer points in the convex case) of the minimization problem. As an application we consider a human location problem: How to travel around the world and prepare the trip of a lifetime.

We study whether fiscal policies, especially public debt, can help to curb the macroeconomic and health consequences of epidemics. Our approach is based on three main features: we introduce the dynamics of epidemics in an overlapping generations model to take into account that old people are more vulnerable; people are more easily infected when pollution is high; public spending in health care and public debt can be used to tackle the effects of epidemics. We show that fiscal policies can promote convergence to a stable disease-free steady state. When public policies are not able to permanently eradicate the epidemic, public debt, and income transfers could reduce the number of infected people and increase capital and GDP per capita. As a prerequisite, pollution intensity should not be too high. Finally, we define a household subsidy policy that eliminates income and welfare inequalities between healthy and infected individuals.

We study a simple model in which two vertically differentiated firms compete in prices and mass advertising on an initially uninformed market. Consumers differ in their preference for quality. There is an upper bound on prices since consumers cannot spend more on the good than a fixed amount (say, their income). Depending on this income and on the ratio between the advertising cost and quality differential (relative advertising cost), either there is no equilibrium in pure strategies or there exists one of the following three types: (1) an interior equilibrium, where both firms have positive natural markets and charge prices lower than the consumer’s income; (2) a constrained interior equilibrium, where both firms have positive natural markets, and the high-quality firm charges the consumer’s income or (3) a corner equilibrium, where the low-quality firm has no natural market selling only to uninformed customers. We show that no corner equilibrium exists in which the high-quality firm would have a null natural market. At an equilibrium (whenever there exists one), the high-quality firm always advertises more, charges a higher price and makes a higher profit than the low-quality one. As the relative advertising cost goes to infinity, prices become equal and the advertising intensities converge to zero as well as the profits. Finally, the advertising intensities are, at least globally, increasing with the quality differential. Finally, in all cases, as the advertising parameter cost increases unboundedly, both prices converge increasingly towards the consumer’s income.