Sustainability, optimality, and viability in the Ramsey model

The Ramsey model of economic growth is revisited from the point of view of viability. A viable state is a state from which there exists at least one tra jectory that remains in the set of constraints of minimal consumption and positive wealth. Viability is presented with a constraint of minimal consumption, then with an additional criterion of economic sustainability. The comparison of viability kernels with or without sustainability shows how much consumption should be reduced and when. The viable-optimal solution in the sense of inter-temporal consumption is obtained on the viability boundary of an auxiliary system. Technological progress works against population growth to favor the possibility for a given state of being viable or viable-sustainable.viability theory, optimization, sustainability, Ramsey model

Sustainability, optimality, and viability in the Ramsey model

The Ramsey model of economic growth is revisited from the point of view of viability compared to optimality. A viable state is a state from which there exists at least one trajectory in capital, consumption, and reproduction that remains in the set of constraints of minimal consumption and positive wealth. There exists a largest set of viable states, including all others, called the viability kernel. This concept is an interesting addition to those of equilibria and optimal paths. Viability is first presented with a constraint of minimal consumption, then with an additional criterion of economic sustainability in the sense of the Brundtland commission, which amounts to requiring a non-decreasing social welfare. The comparison of viability kernels with or without sustainability shows how much consumption should be reduced and when. One strong mathematical result is that the viable-optimal solution in the sense of inter-temporal consumption is obtained on the viability boundary of an auxiliary system. Varying preference, technological, and demographic parameters randomly over simulated viability kernels with and without the Brundtland criterion help identify the determinants of the non-emptiness of the viability kernel and of its volume: technological progress works against population growth to favor the possibility for a given state of being viable or viable-sustainable.Viability theory, Optimization, Sustainability, Ramsey model

Du jardin d'essais colonial à la station expérimentale 1880-1930. : éléments pour une histoire du CIRAD

Cet essai historique sur la recherche agronomique tropicale française comprend deux textes : mise en valeur de l'empire colonial et naissance de l'agronomie tropicale (C. Bonneuil); aux origines de la recherche agronomique tropicale : naissance des institutions (M. Kleiche

Viable Nash Equilibria in the Problem of Common Pollution

Ce working paper fait l'objet d'une publication in Pure and Applied Functional Analysis (online journal), Yokohama Publishers, 2017, 2 (3), pp.427-440. 〈http://www.ybook.co.jp/online2/oppafa/vol2/p427.html〉. 〈hal-01691187〉Two countries produce goods and are penalized by the common pollution they generate. Each country maximizes an inter-temporal utility criterion, taking account of the pollution stock to which both contribute. The dynamic is in continuous time with possible sudden switches to less polluting technologies. The set of Nash equilibria, for which solutions also remain in the set of constraints, is the intersection of two manifolds in a certain state space. At the Nash equilibrium, the choices of the two countries are interdependent: different productivity levels after switching lead the more productive country to hasten and the less productive to delay the switch. In the absence of cooperation, efforts by one country to pollute less motivate the other to pollute more, or encourage the country that will be cleaner or less productive country after switching to delay its transition

Movilizando pericia contra restricciones comerciales: un caso de disputa por la regulación de los OGM en la Organización Mundial del Comercio (OMC)

El procedimiento de solución de diferencias de la Organización Mundial del Comercio (OMC) es un ámbito clave para establecer normas jurídicas mundiales para lo que se considera conocimiento pertinente. Como caso de alto perfil, la disputa comercial de la OMC sobre los OGM movilizó y se apropió de los conocimientos científicos de maneras un tanto novedosas. El Panel interpretó el marco de las SPS (Sanitary and Phitosanitary Agreement) como un requisito para la "evaluación del riesgo", es decir, la cuantificación de las probabilidades y consecuencias, y la imposición de cargas adicionales al demandado para la presentación de pruebas. Al imponer "las aplicaciones más restringidas hasta la fecha de la noción de evaluación del riesgo en materia sanitaria y fitosanitaria" (Peel, 2010: 244), el Panel de la OMC globalizó aún más una "evaluación del riesgo basada en la ciencia" que había surgido durante la administración Reagan de los Estados Unidos (Jasanoff, 2011). Desde el principio, el Panel puso la disputa bajo el Acuerdo Sanitario y Fitosanitario (SPS) a través de una nueva ontología legal; clasificó los transgenes como plagas potenciales y limitó todas las cuestiones ambientales a la categoría de "sanidad vegetal y animal". En el marco de las SPS, que se centraba en los procedimientos de regulación del demandado, el Panel organizó la pericia científica de manera específica para establecer la forma en que se interrogaba a los expertos, las respuestas que darían, su función específica en el ámbito jurídico y la forma en que sus declaraciones complementarían las conclusiones del Panel. Además, éste le dio un giro de procedimiento a la jurisprudencia de la OMC al presentar sus conclusiones como un juicio puramente jurídico-administrativo sobre si los procedimientos reglamentarios de la CE violaban el Acuerdo SPS. Mientras tanto, el Grupo mantuvo implícitos sus propios juicios sobre cuestiones sustantivas de riesgo. Como ilustra este caso, el proceso de solución de diferencias de la OMC crea una nueva experiencia científica para la tarea principal, a saber, cuestionar las restricciones comerciales por ser excesivamente cautelosos. [English] The World Trade Organization (WTO) dispute settlement procedure is a key area for establishing global legal standards for what is considered relevant knowledge. As a high-profile case, the WTO trade dispute over GMOs mobilized and appropriated scientific knowledge in somewhat novel ways. The Panel interpreted the Sanitary and Phitosanitary Agreement (SPS) framework as a requirement for "risk assessment", i.e. the quantification of probabilities and consequences, and the imposition of additional burdens on the defendant for the production of evidence. By imposing "the most restricted applications to date of the notion of SPS risk assessment" (Peel, 2010: 244), the WTO Panel further globalized a "science-based risk assessment" that had emerged during the Reagan administration of the United States (Jasanoff, 2011). From the outset, the Panel placed the dispute under the Sanitary and Phytosanitary Agreement (SPS) through a new legal ontology; classified transgenes as potential pests; and limited all environmental issues to the category of "plant and animal health. Within the SPS framework, which focused on the respondent's regulatory procedures, the Panel organized scientific expertise specifically to establish how the experts were to be questioned, the answers they would give, their specific role in the legal arena, and how their statements would complement the Panel's findings. In addition, the Panel gave a procedural twist to WTO jurisprudence by presenting its findings as a purely legal-administrative judgment on whether EC regulatory procedures violated the SPS Agreement. In the meantime, the Panel implicitly maintained its own judgments on substantive risk issues. As this case illustrates, the WTO dispute settlement process creates new scientific experience for the main task of challenging trade restrictions as overly cautious

Longevity, Age-Structure, and Optimal Schooling

The mechanism stating that longer life implies larger investment in human capital, is premised on the view that individual decision-making governs the relationship between longevity and education. This relationship is revisited here from the perspective of optimal period school life expectancy, obtained from the utility maximization of the whole population characterized by its age structure and its age-specific fertility and mortality. Realistic life tables such as model life tables are mandatory, because the age distribution of mortality matters, notably at infant and juvenile ages. Optimal period school life expectancy varies with life expectancy and mortality. The application to French historical data from 1806 to nowadays shows that the population age structure has indeed modified the relationship between longevity and optimal schooling

Le temps des populations humaines

Noël Bonneuil, directeur d’études Systèmes dynamiques en démographie Le séminaire s’appuie sur les propres recherches des étudiants, cette année économistes, historiens, et démographes. Ceux-ci trouvent dans ce séminaire l’opportunité d’étayer leurs réflexions par une construction mathématique, statistique ou économétrique. Ainsi, la sociologie et l’économie d’une cité ouvrière en Normandie au début du XXe siècle, le suivi au cours de la vie active des emplois d’étrangers, la dynamique de ven..

Mettre en ordre et discipliner les tropiques : les sciences du végétal dans l'Empire français, 1870-1940

À l'interface de l'histoire sociale des sciences et de l'histoire de l'expansion française, ce travail explore les modalités par lesquelles les colonisateurs se sont efforcés de se rendre scientifiquement « maîtres et possesseurs de la nature » tropicale. Les principaux thèmes abordés par cette ethnographie des experts de la « mise en valeur » sont : - La caractérisation de trois « micromondes » où se forgent des pratiques de mise en ordre et des représentations de la nature tropicale..

Le temps des populations

Noël Bonneuil, directeur d’études Systèmes dynamiques en démographie Le séminaire a été scindé en deux cette année. La première partie s’adressait à des étudiants historiens et sociologues. Elle a porté sur l’étude économétrique et statistique du changement dans le cas de migrants arrivant en France dans le but de fonder un commerce. Les étudiants ont été amenés à mettre en œuvre l’analyse des biographies, l’analyse factorielle des correspondances et les modèles de données qualitatives. La se..