Contrairement à l'hypothèse conventionnelle d'égoïsme avancée par la théorie standard, il est largement reconnu que les gens se comportent systématiquement de manière prosociale et, en outre, que la propension à le faire est sensible à plusieurs éléments du contexte décisionnel, qui autrefois étaient systématiquement relégués au second plan. Notre thèse s'intéresse particulièrement au fait que les préférences sociales constituent des éléments contextuels décisifs et examine la mesure dans laquelle les normes sociales peuvent expliquer des déviations comportementales qui autrement pourraient sembler irrationnelles. Dans un contexte où les budgets publics sont limités et ou les défis sociaux et environnementaux sont de plus en plus pressants, les interventions basées sur des approches comportementales peuvent constituer des instruments politiques attrayants, notamment du fait de leur moindre coût en comparaison des mesures basées sur descontraintes réglementaires et/ou sur des incitations économiques. Étant donné que les normes sociales peuvent être un déterminant important des performances globales d'une société dans des domaines très variés, nous étudions plusieurs aspects liés à la conception optimale de ces interventions comportementales qui exploitent les considérations normatives, ainsi que de la dynamique entre les normes sociales et les mesures institutionnelles formelles. Nous réalisons également une revue de la littérature relative à l'impact des interventions basées sur les normes sociales sur les comportementsenvironnementaux ainsi qu'aux mécanismes théoriques sous-jacents permettant d'expliciter le le rôle de ces normes dans le processus décisionnel. / A growing body of empirical evidence demonstrates that decision-making is embedded within complex personal, cognitive, and social contexts that call for a richer understanding of behavior than that described by traditional neoclassical economic theory. Contrary to the conventional selfishness assumption advanced by standard theory, it has now been established that people systematically behave in prosocial ways and furthermore, that the propensity to do so is sensitive to a variety of elements of decision context that have historically been considered irrelevant. We examine the assumptions that social preferences are outcome-regarding and consistent, and the extent to which social norms may be implicated in the divergences from these assumptions.This work has a strong applied focus. In an environment of limited public budgets and increasingly pressing social and environmental challenges, interventions based on behavioral insights can be appealing policy instruments, as they are often more economical than traditional command-and-control or incentive-based tools, and have the potential to generate reliable and immediate behavior change. Given that social norms can be an important determinant of aggregate societal outcomes in a diverse range of contexts, we investigate several aspects of the optimal design of behavioral interventions that leverage normative considerations, as well as the dynamics between social norms and formal institutional measures. These works are complemented by a review of the literature regarding the impact of social norm interventions on proenvironmental behaviors and of several theoretical accounts of the role that social norms play in the decision-making process.Through the use of both laboratory and online experiments (via Amazon Mechanical Turk and the NSF-funded Time-Sharing Experiments for the Social Sciences), the experimental studies that comprise the thesis examine the impact of valence framing on the effectiveness of a normative intervention, the capacity for a single normative intervention to generate heterogeneous behavioral impacts, and the effectiveness of certain informal norm-enforcement mechanisms and their interaction with formal institutional sanctions. From these studies, we draw a number of policy-relevant implications and identify the need for future work on a number of specific issues related to the role of social norms in behavior and accordingly, to the design of effective behavioral interventions that leverage social norms.

A partir des théories et approches de l'économie industrielle (SCP, filières, marchés contestables, comportements stratégiques etc...), complétées par l'économie de l'entreprise et l'économétrie, la thèse crée cinq outils génériques, interfaces entre Théorie et Applications qui sont ensuite appliqués au secteur spatial européen:-Analyse sectorielle (filière globale, stade système, filières satcom et lanceur Ariane 5)-Politique Industrielle (filière Ariane 5, stade système, cluster Aerospace Valley, ESA)-Stratégie des entreprises (Arianespace)-Modélisation et prévision (horizon 2015) à l'aide de l'économétrie-Prospective du secteur spatial européen (horizon à 20-30 ans) L'application au spatial a permis de valider ces outils, forme de pont entre Théorie et Application, mais tout secteur industriel, dont entreprises et pouvoirs publics constituent des acteurs majeurs, représente un champ d'utilisation potentiel. / Contribution of Industrial Economics to the European Space Sector Starting from theories and approaches of Industrial Economics ( SCP, filières, contestable markets, strategic behaviors etc...), complemented with economics of the firm and econometrics, the thesis creates five generic tools as interfaces between Theory and Applications that are then applied to the European space sector:-Sector Analysis (global filière, system stage, satcom and Ariane 5 launcher filières)-Industrial Policy (Ariane 5 filière, system stage, Aerospace Valley cluster, ESA)-Strategy of firms (Arianespace)-Modelling and prevision (2015 horizon) with econometrics-Prospective of the European space sector (20-30 years horizon) Application to Space has permitted to validate these tools, kind of bridge between Theory andApplication, but any industrial sector, whose firms and public authorities constitute the majoractors, represents a potential field for application.

Dans un contexte de crise de développement dans lequel ont été plongés les PMA depuis leurs indépendances et la persistance, voir l’expansion continue de l’économie dite informelle, la dynamisation des micro-entreprises devient un sujet clé afin de développer des PME dynamiques capables de générer de la valeur ajoutée. Dans la réflexion que nous proposons notre ambition est de mieux comprendre les modes de fonctionnement des micro-entreprises et d’identifier les principaux facteurs qui déterminent leur dynamisation et leur transition vers des PME commerciales dynamiques. L’étude fait une synthèse des théories explicatives de l’économie dite informelle et de la micro-entreprise. Pour cela, nous avons réalisé une enquête conduite en 2012 auprès d’un échantillon de 205 micro-entrepreneurs urbains de la république de Mali. Cette thèse analyse l’existence et la réalité de l’économie dite informelle ; étudie la logique de fonctionnement des micro-entreprises ; établit une typologie des MPME en deux groupes en fonction de leurs logiques de fonctionnement et de la taille du capital investi : entreprises de subsistance et entreprises commerciales ; cible les interventions pour chaque type de micro-entreprises et propose des politiques de dynamisation et d’incitation à la formalisation des micro-entreprises dans les PMA. / In a context of development crisis which, the Lest Developed Countries (LDCs) are trapped in since their independences and faced to a persisting if not a contained expanding informal economy, micro enterprises are seen as a solution to boost dynamic Small Medium Sized business (SMEs) that can generate added value. Our reflection in this research project is to shed more light on the operational patterns of micro-enterprises and contribute to identify the main factors that determine their dynamism and thus, their transition to dynamic commercial SMEs. The project presents a synthesis of some of the different theories explaining the so-called informal economy and micro-enterprises. For this purpose, we have conducted a survey in 2012 among a sample of 205 urban micro-entrepreneurs in the Republic of Mali. Our research led us to accept and analyze the very existence and reality of the so-called informal economy; and study the operational logic of micro enterprises and thus come out with a typology of MSMEs into two main categories. The division is made according to the logic of operation and the size of the invested capital: enterprises for mere subsistence or commercial enterprises. For each category, appropriate incentive policies that can prompt micro enterprises to comply with formal legislation in force in the LDCs.

The three chapters all address solvency regulation issues, with a focus on market risks under the Solvency II framework. Chapter 1 deals with “high-level” aspects of Solvency II as main principles and the general structure. Chapters 2 and 3 will be devoted to quantitative issues. Chapter 1 describes the main evolutions that led to the development of Solvency II. The insurance sector has dramatically evolved during the last two decades. Among others developments, we stress the new risks faced by the sector as natural catastrophes, changing demographics or market risks. Insurers become international companies, investing almost 10 trillion € of assets in Europe at the end of 2014 and being increasingly intertwined with banks and other financial sectors. Financial innovation and the refinement of risk management techniques and models developed by companies have gained momentum among the major European insurance companies. Have these evolutions changed the needs for the supervisory of insurance companies? The economic foundation for regulation is based on the presence of market failures, including severe asymmetric information problems and principal-agent conflicts. Insurance consumers, particularly individuals and households, face significant challenges in judging the financial risk of insurers. But the importance of the insurance sector for financial stability has been increasing. A sound regulatory and supervisory system is necessary to maintain efficient, safe, fair and stable financial markets and promote growth and competition in the insurance sector. The difficult conditions experienced by the industry and the shortcomings of the previous regulatory and supervisory framework have forced regulators to take action to change the way in which they regulate insurance companies’ solvency. Recognizing the shortcomings of Solvency I, EU policy-makers undertook the Solvency II project. Solvency I was not consistently applied throughout EU as the directive allowed countries to implement insurance regulation in different ways. Moreover Solvency I did not consider risks fully or in detail. In life business, the major criticism was the lack of consideration of asset risks. Allowances for latest developments in risk management were also inadequate and companies could not use an internal model to calculate the solvency capital. Finally, the increasing presence of conglomerates and groups forced the insurance regulator to align some requirements with the banking regulation, Basel II/III. Due to the differences in their core business activities, banks and insurers regulators’ goal does not imply comparability of the overall capital charges. However, considering the asset side of the balance sheets, the investment portfolios of banks and insurers contain the same asset classes. In order to avoid regulatory arbitrage, the capital charges for the same amount and type of asset risk should be similar. Chapter 2 compares the main regulatory frameworks in Europe: Solvency II and the Swiss Solvency Test, SST, in Switzerland, with a focus on potential market implications. Both systems are quite advanced but some key differences need to be highlighted, including the treatment of assets, in particular sovereign bonds, the consideration of diversification or the risk measure applied. Solvency II uses a Value at Risk at 99.5% whereas the SST is based on a Tail Value at Risk at 99%. Our approach is both qualitative and quantitative. In particular, based on a numerical example, we aim at quantifying the level of regulatory capital prescribed by the standard models. The numerical analysis reveals large differences between capital charges assigned to the same asset class under Solvency II and the SST. Solvency II penalizes investment in stocks, mainly due to a lower diversification benefit under the standard formula. On the other hand the SST model requires a higher capital for bonds, primary due to a stringent risk measure and confidence level. The treatment of EU sovereign bonds under Solvency II is another area of concern as it does not require any capital for spread risk. The question arises to what extent an internal model leads to different capital requirements as compared to the SST and Solvency II models. Therefore we apply an internal approach based on Monte Carlo simulation to derive the necessary capital based on the Value at Risk at 99.5% (in line with the Solvency II standard model) and on the Tail Value at Risk at 99% (in line with the SST standard model). Internal models calculate capital requirements that more closely matches risks of insurers and promote a culture of risk management. To develop internal models, companies need incentives to properly manage their risks, i.e. decreasing capital requirements. One potential benefit of the standard model is that insurers who use it can be compared to one another, whereas internal models are by definition specific to individual insurers. One argument against the standard model is the possibility of some systemic risk. An unusual event in the capital or insurance market could encourage all insurers to take the exact same response, thereby causing a run in the market. The analysis shows that standard and internal models still display large discrepancies in their results, suggesting a long way ahead to achieve a harmonized view between the regulators and the insurance sector. The choice of a statistical model or the refinement of parameters are key concepts when setting up an internal model and appear to be critical in the Solvency Capital Requirement calculation. By calculating and comparing the market risk capital charges for a representative insurer under the Solvency II and the SST standard approach as well as an internal model, we are able to provide evidence that the regulatory framework might have an impact on asset portfolios. The main impacts would be a shift from long-term to shorter-term debt, an increase in the attractiveness of higher-rated corporate debt and government bonds, in particular EU sovereign bonds as the consequence of the special treatment under Solvency II, as well as low level of equity holdings. But it is unlikely that large-scale reallocations will happen in the short term, as transitional arrangements are likely to phase in the implementation of Solvency II over several years. The likely impact on assets portfolios could have also already been anticipating by insurers. Chapter 3 studies the effectiveness of the Solvency II reform to prevent the default probability faced by a life insurance company. The default risk leads to a consequence that policyholders might not get back their initial investment upon default of the insurance company. Therefore, policyholders are concerned with the issues like what probability the insurance company will become bankrupt and which amount they can expect to obtain after taking account of the default risk of the insurer. Starting from a theoretical life insurance company which sells a participation insurance policy containing only a savings component and a single premium inflow, we simulate a life insurance company on an eight-year time horizon. We focus only on market risks as there is no mortality risk attached to the insurance contract. Finally several policies and investment strategies will be analysed. The purpose of the chapter is to evaluate how Solvency II can prevent the company to collapse. The papers discussing Solvency II effectiveness are qualitative in nature. In particular there is little research on the accuracy of the standard formula with regard to the proclaimed ruin probability of 0.5% per year. To do so we compare the probability of default at maturity of the life insurance policy, i.e. if the company has to enough assets to pay what was promised to the policyholders, with the early probability of default forced by Solvency II based on standard and internal models. We have first to calculate the Solvency Capital Requirement as laid down in the directive. One crucial point is the evaluation of liabilities. To do so we use an approach recently applied by the insurance sector called Least-squares Monte Carlo (LSMC). The aim of Solvency II is to monitor insurers on an annual basis. The SCR level can then be interpreted as a regulatory barrier, consistent with a model developed by Grosen and Jørgensen (2002). Key drivers of the ruin probability at maturity include interest rate parameters, portfolio riskiness and investment strategies in bonds. The continuously decrease of interest rates creates a challenge for insurers, especially life insurers that suffer a double impact on their balance sheet: a valuation effect and a decreasing reinvestment returns of premiums and maturing bonds. The latter explain also the riskiness of rolling-bond strategies compared to duration matching strategies. By setting the confidence level to 99.5% per year, the regulator wants to ensure that the annual ruin probability equals to 0.5%. Since the SCR from our internal model equals the 0.5% quantile of the distribution, it exactly matches the targeted ruin probability. Our analysis reveals that the set-up and calibration of the Solvency II standard model are inadequate as the solvency capital derived by the standard formula overestimates the results of the internal model. This is mainly the consequence of an overestimated equity capital and a lower diversification benefit. The 0.5% proclaimed goal under Solvency II is not reached, being too conservative. One declared goal of the directive is to decrease the duration gap between assets and liabilities. Solvency II penalizes then rolling-bond strategies. The long-term feature of our policy should impact the level of regulatory capital. As Solvency II is based on a quantile measurement, we define the solvency capital using the default probability objective for different horizons. SCR is not systematically a decreasing function of the time horizon even if a decreasing form appears on long-term. This shows undoubtedly that a horizon effect exists in terms of measurement of solvency. As the standard model overestimated the internal model capital we expect a forced default probability higher than 0.5% under the Solvency II framework. The SCR barrier stops the company more often than it should be. This can be interpreted as one cost of regulation, i.e. closing down financially sound at maturity companies. The analysis of the evolution of default probabilities as a function of time horizon reveals that ruin probabilities at maturity lie always below the Solvency II objective. Furthermore the gap between the observed default at maturity and the Solvency II objective is increasing over time; the situation is even worse for longer-term insurance products. Finally stakeholders are more interested in their expected return than in the default probability. A cost of regulation defined as the difference between stakeholder’s returns with and without regulatory framework exists, particularly for shareholders. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished

This thesis consists of three independent essays on the design of matching markets, with a primary goal to understand how information interacts with matching mechanisms especially in the applications to school choice and college admissions. The first chapter compares theoretically the non-strategyproof Boston mechanism and the strategy-proof deferred acceptance mechanism when taking into account that students may face uncertainty about their own priorities when submitting preferences, one important variation from the complete information assumption. The second chapter evaluates the effectiveness of a strategy-proof mechanism when students have to submit preferences before knowing their priorities using both theory and data. The third chapter turns attention to a new mechanism that is sequentially implemented and can encourage truth-telling. Nevertheless, such implementation often faces time constraint. This chapter therefore offers an inquiry of the pros and cons of the time-constrained sequential mechanism. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished

Dans les sociétés en voie de développement comme la Syrie et l'Egypte, les assurances sociales constituent un pilier important dans les mesures où elles jouent un rôle important dans le financement de la croissance économique / In developing societies like Syria and Egypt, social insurance can play an important role in the in the financing of economic

Doctorat en sciences sociales, politiques et économiques / info:eu-repo/semantics/nonPublished

L’étude de la réalité de la criminalité démontre que celle-ci a essentiellement un but économique. L’aspect financier peut aussi être un moyen significatif, notamment dans le cas du terrorisme. Pourtant, la réponse à la criminalité ne prend que très peu en compte la réalité économique de la criminalité et est tournée, de façon historique, vers la sanction physique. Le droit pénal concurrençant le droit fiscal, y compris sur des infractions de nature économique. Partant de ce constat, il devient nécessaire de faire évoluer la réponse à la criminalité afin de mieux répondre à cette réalité. Parmi les moyens déjà existants, le droit fiscal représente de nombreux avantages, notamment par le fait qu’il est conceptuellement tourné vers la lutte contre les flux financiers illicites, que ceux-ci soient ou non d’origine criminelle. Si le corpus juridique lié à la lutte contre la criminalité est peu tourné vers le droit fiscal, les quelques cas présents démontrent que celui-ci a un apport significatif, notamment par les moyens dont dispose l’administration fiscale (même s’ils sont sous-utilisés) en matière de recherche d’informations relatives aux flux financiers. La lutte contre la criminalité gagnerait aussi en efficacité si le paradigme de la réponse pénale était changé. Il faudra pour cela adopter une approche économique à l’instar de l’approche et des moyens mis en œuvre dans le cas de la fraude fiscale. Que ce soit en recherchant des sanctions économiques et non plus pénale ou en traitant l’environnement criminel comme un tout. / The study of the reality of crime shows that it has essentially an economic purpose. The financial aspect can also be a significant one, especially in the case of terrorism. However, the response to crime takes very little account of the economic reality of the crime and is, historically, based on criminal punishment. The tax law is in concurrence with the criminal law. In regard to this observation, it becomes necessary to change the response to crime in order to better meet this reality. Among the existing means, the tax law is representing several advantages, including the fact that it is conceptually directed to fight illicit financial flows, whether they are of criminal origin or not. If the body of law related to the fight against crime is not tax law oriented, the few existing cases show that it has a significant contribution, including the capacity of the tax administration (even though it is under-used) in research on information flows. The fight against crime could become much more effective if the paradigm of criminal law had changed. This change could be achieved by adopting an economic approach, like the approach and means used in the case of tax evasion. Whether seeking economic sanctions rather than criminal, or dealing with the criminal environment as a whole.

L'étude du développement des pays du Sud a réellement pris son essor après la deuxième guerre mondiale dans un contexte marqué par la reconstruction des économies des pays européens détruites par le conflit, l'accession de nombreux pays « sous-développés » à l'indépendance et la diffusion du modèle fordiste dans les pays du Nord. Dans la perspective du développement de ces pays dits sous-développés, quelques théories sont élaborées. Celles civont tenir compte de la structure du 1' économie mondiale, notamment de celle des pays du Nord, afin de proposer aux pays émergents un cadre théorique et idéologique susceptible de leur convenir. C'est ainsi que, sur la base de 1 'hypothèse que le sous-développement est une conséquence de la sous-industrialisation, le développement du secteur productif à travers les grandes unités de production leur a été proposé. Suivant principalement trois stratégies, cetteapproche d'industrialisation fait l'objet d'une large utilisation dans ces pays. Mais après quelques décennies d'expérience, les résultats de ce modèle d'industrialisation restent variables suivant les pays ou même les continents. Si en Asie et en Amérique latine, on note un progrès substantiel dans le développement industriel, en Afrique, en revanche, le secteurproductif est resté quasi-stagnant avec un apport marginal notamment en termes de création d'emplois malgré les moyens consentis à sa transformation. Mais à partir du milieu des années soixante-dix, le secteur industriel amorce une phase de transformation. On assiste à 1' émergence et au développement des petites et moyennesstructures de production. Cette catégorie d'entreprises suscite beaucoup d'intérêts eu égard à ses caractéristiques et à ses capacités d'apporter des réponses notamment au problème de chômage. Suivant quelques approches et stratégies, ces structures de production se développent aussi bien dans les pays industrialisés que dans les pays en développement et contribuent significativement à la création d'emplois et de la richesse, à la répartition des foyers de production et au développement local. Mais malgré l'importance des petites et moyennes industries (PMI) dans une économie, notamment en termes de création d'emplois, subsistent quelques obstacles qui tentent de freiner leurs efforts. La stratégie de gestion de 1' entreprise mise en place, le mode d'organisation du système dans lequel appartient l' entreprise et les facteurs provenant de 1' environnement extérieur à 1' entreprise sont considérés comme des principaux facteurs d'obstacle à la création d'emplois dans les petites et moyennes entreprises de production. Considérant que les petites et moyennes industries de 1' économie camerounaise (PMI-EC), eu égard à leur mauvaise performance en termes de création d'emplois, font face à des obstacles, nous avons opté pour l'approche exogène (c'est-à-dire que les obstaclesproviennent de l'environnement extérieur) qui cadre avec le contexte des pays en développement pour identifier et quantifier les éléments d'entrave. Les résultats de l'analyse des données obtenues d'une enquête menée au niveau national auprès de 68 PMI montrent que les obstacles à la création d'emplois dans les PMI-EC proviennent aussi bien des institutions de financement que des pouvoirs publics. Il s'agit de l'absence du soutien des pouvoirs publics, du niveau élevé de la fiscalité, du niveau élevé du üiux d'intérêt des prêts et des conditions du financement informel. Dans la perspective de 1' élaboration de la politique de création d'emplois par les PMI-EC aux niveaux national et régional, quelquesrecommandations sont formulées. / The study of the development of the South's countries really took its development after the Second World W ar in a context characterized by the reconstruction of the savings of the European countries destroyed by the conflict, the entry of numerous "underdeveloped" countries in the independence and the distribution of the Ford Mode! in the North's countries. In the prospect of the development of these underdeveloped said countries, sorne theories are elaborated. These are going to take into account the structure of the world eco nom y, in particular of that of the countries of the North, to propose in emerging co un tries a theoretical and ideological frame susceptible to be convenient for them. And so, on the basis of thehypothesis that the underdevelopment is a consequence of the sub-industrialization, the development of the productive sector through the bulks of production was proposed to them. According to main! y three strategies, this approach of industrialization is the abject of a wide use in these countries. But after sorne decades of experience, the results of this mode! of industrialization remain variable according to countries or even continents. If in Asia and in Latin America, we note a substantial progress in the industrial development, in Africa, on the other hand, the productive sector remained quasi-stagnant with a marginal contribution in particular in terms of job creation in spite of the means granted on its transformation. From the middle of the seventies, the branch of industry begins a phase of transformation. We attend the emergence and the development of the small and average structures of production. This category of companies arouses many interests in consideration its characteristics and its capacities to bring answers in particular to the problem ofunemployment. According to sorne approaches and strategies, these structures of production develop as well in the industrial nations as in the developing countries and contribute significantly to the creation of jobs and the wealth, to the distribution of the homes of production and to the local development. But in spite of the importance of small and mediumsized industries (SMSI) in an economy, in particular in terms of job creation, remain sorne obstacles which try to slow down their efforts. The strategy of management of the organized company, the mode of organization of the system in which belongs the company and factors resulting from the environment outside the company are considered as main factors of obstacle to the job creation in SMSI. Considering that the small and medium-sized industries of the Cameroonian economy, in consideration of their bad performance in terms of job creation, put in front of obstacles, we opted for the exogenous approach (that is the obstacles result from the outside environment), which suits to the context of developing countries, to identify and quantify these elements of obstacle. The results of the data analysis obtained from an investigation led to the national leve! with 68 SMSI shows that the obstacles which slow down the job creation in the EC-SMSI result as well from institutions of financing as from public authorities. It is about the absence of the support of public authorities, about the high leve! of the tax system, about the high leve! of the interest rate of the Jo ans and about the conditions of the informal financing. In the prospect of the elaboration of the po licy of job creation by the EC-SMSI atthe national and regionallevels, sorne recommendations are formulated.

Cette thèse de doctorat porte sur le débat concernant le rôle de l'initiative individuelle et de l'intervention publique dans l'économie politique et sociale de Léon Walras. Dans une première partie on analyse d'abord la philosophie d'Auguste Walras qui a posé les bases d'une véritable démarche scientifique pour l'économie politique et la théorie de la propriété et la communauté au XIXe siècle. Léon Walras réalisera son propre projet d'économie politique et sociale par un nouvel apport vers une vision tripartite, offrant ainsi une vision d'ensemble des trois sciences (économie pure, économie appliquée, économie sociale). Le rôle de l'initiative individuelle et de l'intervention publique dans l'économie politique de Leon Walras sera précisé en deux temps: d’abord la théorie de la répartition et ensuite celle de la production, considérées comme une première et seconde question sociale. La deuxième partie, présentant une continuation logique de notre thèse propose des exemples concrets à la fois pour comprendre le modèle théorique walrasien mais également pour examiner l'actualité de ses propos. L'importance conférée à l'intervention publique sera étudiée dans les travaux de Léon Walras portant sur la propriété intellectuelle, la nationalisation des terres et les chemins de fer. / This doctoral thesis relates to the debate on the role of initiative and public participation in the political and social economy of Leon Walras.In the first part the analysis focuses on the philosophy of August Walras who laid the foundation of a real scientific approach to the political and economic theory of property and community in the 19th century. Leon Walras elaborates his own project of political and social economy through a new contribution to a triple vision offering an entire insight by three sciences (pure, applied and social economics). The role of personal initiative and public participation in the political economy of Leon Walras will be revealed through: the redistribution theory and the production theory known as the first and second social question. The second part, following the logic of the thesis, proposes concrete examples in order to understand Walras' theory model as well as to study the topicality of these terms. The importance conferred on public participation will be explored in the works of Leon Walras on intellectual property, nationalization of land and railroad.