Documents de travail

Résumé This paper considers the dynamics of pollution and sustainable growth in a context where the detrimental effects of pollution on total factor productivity can push the economy to a point of collapse. With environmental policy constrained by tax revenues, we investigate how the proximity to collapse -distance to the end -influences the balance between mitigation and adaptation spending. We show that adaptation policies are recommended when pollution intensity is high, whereas mitigation policies may be more effective when pollution intensity is low. Financing these policies by a carbon tax is more effective than an income tax. Examining the welfare of present and future generations, we reveal that the trade-off between mitigation and adaptation does not align across generations: while current generations may prefer adaptation, future generations tend to benefit more from mitigation.
Mots clés Environmental policy, Fiscal policy, Sustainability, Environmental damage
Télécharger HAL Google Scholar
Résumé Between 1954 and 1998, the tobacco industry funded more than 1,900 research projects at a total cost of $355 million, on topics such as the roles of heredity and nutrition in cancer. Even though legitimate, this research was intended to divert attention from the harmful effects of tobacco. We provide the first formal analysis of such diversion research. We show that special interests may have strong incentives to affect the scientific agenda, even when the research itself is unbiased. This form of scientific lobbying yields large welfare losses and raises concerns about the private funding of research.
Mots clés Scientific Uncertainty, Scientific lobbying, Private research funding
Télécharger HAL Google Scholar
Résumé We propose a mean-field game (MFG) set-up to study the dynamics of spatial agglomeration in a continuous space-time framework where trade across locations may follow a broad class of static gravity models. Forward-looking intertemporal utility-maximizing agents work and migrate in a twodimensional geography and face idiosyncratic shocks. Equilibrium wages and prices depend on their common distribution and adjust statically according to the underlying trade model. We first prove existence and uniqueness of the static trade equilibrium. We then prove existence of dynamic equilibria. In the case of Krugman (1996)'s racetrack economy, we obtain closed-form solutions for small sinusoidal perturbations around the steady state, and we identify the sets of parameters that lead to agglomeration or dispersion. We exploit the MFG structure of the model to explicitly quantify how uncertainty and forward-looking expectations contribute to agglomeration and dispersion. In particular, we show that, regardless of the static trade model, forward-looking expectations always promote agglomeration, but cannot reverse the dominant pattern that would arise under myopic behavior.
Télécharger HAL Google Scholar
Résumé We propose a mean-field game (MFG) set-up to study the dynamics of spatial agglomeration in a continuous space-time framework where trade across locations may follow a broad class of static gravity models. Forward-looking intertemporal utility-maximizing agents work and migrate in a twodimensional geography and face idiosyncratic shocks. Equilibrium wages and prices depend on their common distribution and adjust statically according to the underlying trade model. We first prove existence and uniqueness of the static trade equilibrium. We then prove existence of dynamic equilibria. In the case of Krugman (1996)'s racetrack economy, we obtain closed-form solutions for small sinusoidal perturbations around the steady state, and we identify the sets of parameters that lead to agglomeration or dispersion. We exploit the MFG structure of the model to explicitly quantify how uncertainty and forward-looking expectations contribute to agglomeration and dispersion. In particular, we show that, regardless of the static trade model, forward-looking expectations always promote agglomeration, but cannot reverse the dominant pattern that would arise under myopic behavior.
Télécharger HAL Google Scholar
Résumé This paper introduces the African Debt Database (ADD) -a new, comprehensive dataset that traces both domestic and external debt instruments at a granular level. The main innovation is a detailed mapping of Africa's domestic debt markets, drawing on rich, new data extracted from government auction reports and bond prospectuses. The database covers over 50,000 individual government loans and securities issued by 54 African countries between 2000 and 2024, amounting to a total of USD 6.3 trillion in debt. For each instrument, it provides harmonized micro-level information on currency, maturity, interest rates, instrument type, and creditor. The data reveal the growing dominance of domestic debt in Africa -albeit with substantial cross-country variation. Four stylized facts stand out: (i) the rapid expansion of domestic debt markets, especially in middle-income countries; (ii) the wide dispersion in borrowing costs and real interest rates; (iii) large cross-country differences in maturity structures and associated rollover risks; and (iv) a rising debt-service burden, particularly due to international bonds. Generally, this project shows that debt transparency is both feasible and valuable, even in data-scarce environments.
Mots clés Africa, Domestic Markets, Development Finance, Public debt, Sovereign Borrowing
Télécharger HAL Google Scholar
Résumé In contrast to standard economic models, recent empirical evidence suggests that agents often operate based on subjective and divergent views of the competitive landscape. We develop a novel framework in which such imperfections are explicitly modeled through subjective perception networks, and introduce the concept of perception-consistent equilibrium (PCE), in which agents' actions and conjectures respond to the feedback generated by perceived competition. We establish the existence of equilibrium in broad classes of aggregative games. The model typically yields multiple equilibria, including outcomes that feature patterns of localized exclusion. Remarkably, heterogeneity in beliefs induces perceived competition rents-payoff differentials that arise purely from subjective misperceptions. We further show that PCE actions correspond to ordinal centrality measures, with eigenvector centrality emerging as a behavioral benchmark in separable payoff environments. Finally, a graph-theoretic taxonomy of PCEs reveals a hierarchical structure that ranks perceived competition rents. We also give conditions under which a unique stable equilibrium exists.
Mots clés Eigenvector centrality, Perceived competition rent, Ordinal centrality, Bounded rationality, Exclusionary equilibria, Perception-consistent equilibrium, Competition
Télécharger HAL Google Scholar
Résumé This paper extends the standard two-period prevention model by incorporating anticipatory emotions. We introduce an additional cost, referred as the emotional load, which is endogenously determined by future risk but can be mitigated by current preventive effort. We show that a more intense emotional load incentivizes the emotional agent to increase investment in either self-insurance or self-protection. By contrast, greater uncertainty sensitivity has an ambiguous effect: It depends on the curvature of the emotional load function and wealth. When savings are substitutes, the effect of these parameters may diverge, whereas they align when savings are complements to risk prevention. Finally contrasting our setting with a setting without uncertainty or emotions, we show that, under prudence, the introduction of a zero-mean risk leads to a higher optimal level of self-insurance. Anxiety amplifies the incentive to reduce risk by lowering present well-being.
Mots clés Uncertainty, Anticipatory emotions, Self-protection, Self-insurance
Télécharger HAL Google Scholar
Résumé Deviations from Bayesian updating are traditionally categorized as biases, errors, or fallacies, thus implying their inherent "sub-optimality." We offer a more nuanced view. In learning problems with misspecified models, we show that some non-Bayesian updating can outperform Bayesian updating.
Mots clés Learning, Bayesian, Consistency
Télécharger HAL Google Scholar
Résumé We examine how the 2015 relaxation of China's one-child policy affected marriage outcomes. Before the reform, some groups were already permitted to have two children. In China, where the sex ratio is heavily skewed toward men, being exempt from the one-child constraint may have been a desirable characteristic for marriage, increasing men's marriage odds. Using detailed policy data on exemptions and individual data from 2010-2018, we find that after the relaxation, men previously allowed a second child are less likely to marry compared to those not allowed. There is no effect for women. The results suggest that differential fertility constraints distorted who got married by advantaging certain men when there was a demand for a second child and strong marriage competition. Furthermore, suggestive evidence shows that the relaxation increased matching by education when exemptions were moderately widespread, indicating that fertility constraints also shaped who married whom.
Mots clés Fertility, Family planning, Marriage, China
Télécharger HAL Google Scholar
Résumé This paper introduces demotivation in the context of social comparison in networks. Social comparison is modeled as a status effect rewarding or penalizing agents according to their relative performance with respect to local peers. A demotivated agent faces both a reduced marginal return to effort and a psychological cost. In the absence of demotivation, social comparison leads to higher effort levels but reduces equilibrium welfare. Introducing demotivation leads to two main findings. First, it generates a network game of strategic substitutes. Second, despite the individual psychological costs incurred by demotivated agents, it can enhance overall welfare—by alleviating social pressure to exert effort and by generating positive externalities for peers.
Mots clés Social Comparison, Demotivation, Networks, Strategic Substitutes, Equilibrium Welfare
Télécharger HAL Google Scholar
Résumé This paper provides a simple uni…ed axiomatic framework for appraising the central tendency of distributions of a single attribute (pie) among a collection of individuals depending upon the available measurement of the attribute. Two types of measurement are considered: cardinal and ordinal. For each of them, three properties are posited on an ordering of distributions of numbers among individuals. The two …rst properties are the anonymity requirement that permutations of the same list of numbers be equivalent and the weak Pareto requirement that a strict increase in the value of the variable for all individuals be favorably appraised. The third property requires that inverting the numerical measurement of the variable leads to an inversion of the ranking of the any two distributions to which the inversion is applied. The mean of a distribution is shown to be the only ordering of distributions consistent with cardinal measurability that satis…es those three requirements in the cardinal context while the median is the only such ranking consistent with ordinal measurability of the variable that sat-is…es those same requirement if the number of individuals is odd. If the number of individuals is even, then those three requirements applied to the ordinal context are shown to be inconsistent.
Mots clés Consistency, Measurement, Ordinal, Cardinal, Median, Mean
Télécharger HAL Google Scholar
Résumé This article establishes a direct proof of the equivalence between two incomplete rankings of distributions of an ordinal attribute. The first ranking is the possibility of going from one distribution to another by a finite sequence of Hammond transfers. The second ranking is the intersection of two dominance criteria introduced by Gravel et al. (Economic Theory, 71 (2021), 33-80). The proof constructs an algorithm that provides a series of Hammond transfers, between any two distributions related by the intersection of the two dominances.
Mots clés Hammond Transfers, Inequality, Algorithm
Télécharger HAL Google Scholar
Résumé Agricultural policies in poor rural developing countries have the potential to improve both household nutrition and agricultural income. But can these policy consequences be reconciled? This is not obvious because many policies are deficient. Moreover, in villages, mismatches have been observed between nutrition and profit indicators. However, incomes raised by such policies may generate nutrition improvement. In Niger, a major program directed to agro-pastoralists is the 3N Initiative. Do these policies enhance households’ agricultural profit and dietary intakes? And if so, is it because of an income effect, or through alternative channels? Using an agropastoral survey conducted in 2016 Niger, we find that livestock extension services that reduce calorie intake while improving diet diversity operate mostly through an increased household’s pastoral profit. In contrast, veterinary services and low-cost livestock feed programs improve diet diversity, but do not affect profit and calories. Because livestock extension services foster households specializing in cattle and sheep rearing and sometimes switching to transhumance, they restrict their access to energy-dense cereals. This generate a perverse consequence on caloric intakes, despite rising animal calories. Therefore, nutritional policy-makers should better account for agro-pastoralist access to cereal markets and monitor whether policies generate differential incentives, especially through profit, for specific specialization or lifestyle.
Télécharger HAL Google Scholar
Résumé The transition towards a sustainable food system requires comprehensive changes in food production and consumption, shaped by the interplay of public policy, market forces, and cultural norms. We develop a model to analyse the role of sustainable food culture in shaping consumption choices, particularly in terms of purchasing from short food supply chains. The model accounts not only for the heterogeneity of preferences and their evolution but also for the heterogeneity of incomes. This allows for a discussion of the effectiveness of policies fostering sustainable food consumption choices, considering their varying impacts across income levels. The results suggest that if policy makers seek to promote a sustainable food system, public policies must be carefully designed, as their effects can be uncertain and may impact low-income households.
Mots clés Culture, Sustainable food, Short food supply chain, Income distribution
Télécharger HAL Google Scholar
Résumé This paper develops a dynamic model of addiction on networks, where individuals’ consumption is shaped by peer influence. We analyze the longrun effects of social interactions by characterizing steady-state consumption as a function of both network position and forward-looking behavior. We also examine the welfare implications of network structure and evaluate the effectiveness of various public policies aimed at reducing the demand for addictive goods. In particular, we study a key-player policy—modeled as a targeted rehabilitation program—that leverages the network’s interpersonal influences to maximize impact.
Mots clés Addiction, Peer Network, Rational addiction, Time-inconsistency
Télécharger HAL Google Scholar
Résumé Experts argue that the adoption of healthy sanitation practices, such as hand washing and latrine use, requires focusing on the entire community rather than individual behaviors. According to this view, one limiting factor in ending open defecation lies in the capacity of the community to collectively act toward this goal. Each member of a community bears the private cost of contributing by washing hands and using latrines, but the benefits through better health outcomes depend on whether other community members also opt out of open defecation. We rely on a community-based intervention carried out in Mali as an illustrative example (Community-Led Total Sanitation or CLTS). Using a series of experiments conducted in 121 villages and designed to measure the willingness of community members to contribute to a local public good, we investigate the process of participation in a collective action problem setting. Our focus is on two types of activities: (1) gathering of community members to encourage public discussion of the collective action problem, and (2) facilitation by a community champion of the adoption of individual actions to attain the socially preferred outcome. In games, communication helps raise public good provision, and both open discussion and facilitated ones have the same impact. When a community member facilitates a discussion after an open discussion session, public good contributions increase, but there are no gains from opening up the discussion after a facilitated session. Community members who choose to contribute in the no-communication treatment are not better facilitators than those who choose not to contribute.
Mots clés Public good provision, Behavioral experiments, Community-based development, Sanitation
Télécharger HAL Google Scholar
Résumé Using data from a selection of Latin American countries affected by El Niño-Southern Oscillation climate phenomena, we observe that extreme weather events can be highly disruptive for an economy, particularly in the agricultural sector, while also giving rise to inflationary pressures. Motivated by these findings, this paper examines the optimal stabilization policies for a climate-vulnerable economy with two segmented sectors: agriculture (producing food) and manufacturing. In response to climate disasters affecting agriculture, it is found to be optimal to increase fiscal transfers to farmers while maintaining core inflation at its target level. Deviating from the optimal policy mix results in smaller welfare losses as long as core inflation remains stabilized.
Mots clés E-DSGE modeling, Optimal Monetary and Fiscal Policy, Dual Economy, Physical risk, Climate change
Télécharger HAL Google Scholar
Résumé Based on the calibration of a simple model, we decompose the decline in the labor share into four structural components: task displacement, labor rents, capital rents, and labor-capital substitution effect. Our estimation suggests that task displacement and the switch of distributed rents from labor to capital are the main drivers of the labor share decline over the past three decades. On the other hand, the neoclassical substitution effect seems not to have a long term impact on the labor share.
Mots clés Productivity, Rate of return on capital, Markup, Capital rents, Labor rents, Automation, Task displacement, Labor share
Télécharger HAL Google Scholar
Résumé This paper analyzes how collateral quality shocks affect banks' liquidity management and the risk-free rate. We develop a model where banks manage liquidity through near-cash assets and marketable securities subject to idiosyncratic and/or aggregate shocks. Collateral quality deterioration leads to non-monotonic changes in liquidity holdings: moderate declines reduce cash holdings via lower market returns, while severe declines cause precautionary hoarding and market freezes. Reduced collateral quality depresses the risk-free rate. Policy interventions, including liquidity regulation and negative interest rate policies can mitigate these effects. Our findings highlight the risks of collateral quality shocks and the importance of policy complementarities in addressing liquidity issues.
Mots clés Cash-hoarding, Negative interest rate, Liquidity regulation, Collateral, Risk-free rate, Interbank market
Télécharger HAL Google Scholar
Résumé In this paper, we examine the possibility for a regulator to reduce policy costs by substituting a voluntary policy based on a legislative threat to an active harvest control. Specifically, we focus on fisheries where the regulator aims to maintain an optimal level of conservation through a voluntary agreement. To achieve this, we identify a mandatory regulation that can serve as a threat to ensure voluntary compliance and avoid regulation costs. However, threats differ from effective policies. To be enforceable, they must be validated through a legislative process, the outcome of which is uncertain and subject to objections. Consequently, we introduce of a random delay in its application and address issues of social acceptability. This threat rests upon two pillars: a moratorium with financial compensation followed by an Individual Transferable Quota (ITQ) mechanism, and a suitably chosen tax on harvesting capacity to deter deviations. We use data from the scallop fishery in the Bay of Saint-Brieuc (France) to illustrate this voluntary mechanism.
Mots clés Voluntary agreements, Fisheries, Conservation policies, Dynamic games
Télécharger HAL Google Scholar