TREICH Nicolas

Standard benefit-cost analysis often ignores distortions caused by taxation and the heterogeneity of taxpayers. In this paper, we theoretically and numerically explore the effect of imperfect taxation on the public provision of mortality risk reductions (or public safety). We show that this effect critically depends on the source of imperfection as well as on the individual utility and survival probability functions. Our simulations based on the calibration of distributional weights and applied to the COVID-19 example suggest that the value per statistical life, and in turn the optimal level of public safety, should be adjusted downwards because of imperfect taxation. However, we also identify circumstances under which this result is reversed, so that imperfect taxation cannot generically justify less public safety.

The social value of risk reduction (SVRR) is the marginal social value of reducing an individual’s fatality risk, as measured by some social welfare function (SWF). This Article investigates SVRR, using a lifetime utility model in which individuals are differentiated by age, lifetime income profile, and lifetime risk profile. We consider both the utilitarian SWF and a “prioritarian” SWF, which applies a strictly increasing and strictly concave transformation to individual utility. We show that the prioritarian SVRR provides a rigorous basis in economic theory for the “fair innings” concept, proposed in the public health literature: as between an older individual and a similarly situated younger individual (one with the same income and risk profile), a risk reduction for the younger individual is accorded greater social weight even if the gains to expected lifetime utility are equal. The comparative statics of prioritarian and utilitarian SVRRs with respect to age, and to (past, present, and future) income and baseline survival probability, are significantly different from the conventional value per statistical life (VSL). Our empirical simulation based upon the U.S. population survival curve and income distribution shows that prioritarian SVRRs with a moderate degree of concavity in the transformation function conform to widely held views regarding lifesaving policies: the young should take priority but income should make no difference.

Although animal agriculture is critical to the subsistence of smallholders in some poor countries, the global detrimental impact of animal farming is now both well documented and overwhelming. Animal farming is a primary cause of deforestation (De Sy et al., 2015), biodiversity loss (Machovina et al., 2015), antibioresistance (O’Neill, 2015) and infectious diseases emergence and amplification (Rohr et al., 2019). Moreover, it contributes significantly to water pollution, water scarcity and climate change (Godfray et al., 2018. Poore & Nemecek, 2018. Springmann et al., 2017). Additionally, the exploitation of farmed animals, especially in its widespread intensive forms, raises various moral issues. In this paper, we discuss another impact of animal farming, that on air pollution and in turn on human health. While this impact is also potentially considerable, we stress that it has been largely overlooked by regulators as well as by researchers, and in particular by economists.

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Many individuals have empathetic feelings towards animals but frequently consume meat. We investigate this “meat paradox” using insights from the literature on motivated reasoning in moral dilemmata. We develop a model where individuals form self-serving beliefs about the suffering of animals caused by meat consumption in order to alleviate the guilt associated with their dietary choices. The model predicts that the price of meat has a causal effect on individuals’ beliefs: high prices foster realism by lowering the returns to self-deception, which magnify the price elasticity of meat consumption. The model also predicts a positive relationship between individuals’ taste for meat and their propensity to engage in self-deception, a causal effect of aggregate consumption on individual beliefs, and the coexistence of equilibria of “collective realism” and “collective denial”.

The French abstract was not provided by the author.

Research in economics is anthropocentric. It only cares about the welfare of humans, and usually does not concern itself with animals. When it does, animals are treated as resources, biodiversity, or food. That is, animals only have instrumental value for humans. Yet unlike water, trees or vegetables, and like humans, most animals have a brain and a nervous system. They can feel pain and pleasure, and many argue that their welfare should matter. Some economic studies value animal welfare, but only indirectly through humans’ altruistic valuation. This overall position of economics is inconsistent with the utilitarian tradition and can be qualified as speciesist. We suggest that economics should directly value the welfare of sentient animals, at least sometimes. We briefly discuss some possible implications and challenges for (environmental) economics.

Diagnostic tests allow better informed medical decisions when there is uncertainty about a patient’s health status and, therefore, about the desirability to undertake treatment. This paper studies the relation between the expected value of diagnostic information and a patient's risk aversion. We show that the ex ante value of diagnostic information increases with risk aversion for diseases with low prevalence, but decreases with risk aversion for diseases with high prevalence. On the other hand, the ex post value of diagnostic information always increases with the patient's degree of risk aversion.

In this paper, we discuss the health impact of animal agriculture through air pollution. While this impact is potentially considerable, we argue that it has been largely overlooked by regulators as well as by researchers, and in particular by economists. We discuss the methods, results, limitations, and uncertainties of existing scientific studies on this impact, and conclude with a tentative discussion of the regulation of air pollution in agriculture.

This paper investigates the difference between relative risk aversion and resistance to intertemporal substitution in climate risk modeling. Stochastic recursive preferences are used in a stylized numerical model using preliminary ICCS 1998 scenarios on the economy and climate. It is shown that higher risk aversion leads to an increase in the optimal level of energy taxation. Increasing the resistance to intertemporal substitution has the same effect as increasing the discount rate, as long as the risk is not too great. The implications of these results for the debate on discounting and sustainability under uncertainty are discussed.

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Most infectious diseases in humans originate from animals. In this paper, we explore the role of animal farming and meat consumption in the emergence and amplification of infectious diseases. First, we discuss how meat production increases epidemic risks, either directly through increased contact with wild and farmed animals or indirectly through its impact on the environment (e.g., biodiversity loss, water use, climate change). Traditional food systems such as bushmeat and backyard farming increase the risks of disease transmission from wild animals, while intensive farming amplifies the impact of the disease due to the high density, genetic proximity, increased immunodeficiency, and live transport of farmed animals. Second, we describe the various direct and indirect costs of animal-based infectious diseases, and in particular, how these diseases can negatively impact the economy and the environment. Last, we discuss policies to reduce the social costs of infectious diseases. While existing regulatory frameworks such as the "One Health" approach focus on increasing farms' biosecurity and emergency preparedness, we emphasize the need to better align stakeholders' incentives and to reduce meat consumption. We discuss in particular the implementation of a "zoonotic" Pigouvian tax, and innovations such as insect-based food or cultured meat.

The COVID-19 pandemic reminds us of the importance of health problems at the interface between humans, animals and the environment: nearly two thirds of human infectious diseases come from pathogens shared with wild or domestic animals. While the number of people suffering from infectious diseases is decreasing, especially in Western regions, paradoxically the number of infectious epidemics continues to grow. The role played by the degradation of ecosystems, in particular deforestation, in the phenomenon of "jumping the species barrier" is questioned, as well as, more generally, that of our lifestyles (diets and food chains, trade...). Thus, this pandemic suggests not only to re-evaluate existing public policies of sanitary control and management, but also to see how they should be completed at the level of economic behavior orientation. In order to prevent future epidemics and reduce their impacts, it is important to understand the mechanisms that generate epidemics and the increase in their frequency or severity, and in particular the extent to which global changes and anthropogenic factors modify the situation. If it is difficult, even illusory, to prevent animals from developing diseases that can be transmitted to humans, and if it is necessary to control their appearance and to manage the sanitary and economic consequences, one of the ways to reduce the risks of epidemics would be to act upstream. In this respect, the preservation of natural habitats, the reduction of meat consumption, the reduction of the size of intensive livestock farms and the cessation of the marketing (legal or not) of wild animal meat would constitute coherent and effective measures for tomorrow's "one health" public health policies.

We show that ambiguity aversion increases the value of a statistical life as soon as the marginal utility of wealth is higher if alive than dead. The intuition is that ambiguity aversion has a similar effect as an increase in the perceived baseline mortality risk, and thus operates as the “dead anyway” effect. We suggest, however, that ambiguity aversion should usually have a modest effect on the prevention of ambiguous mortality risks within benefit-cost analysis, and can hardly justify the substantial “ambiguity premium” apparently embodied in environmental policy-making.

NGOs often vary in terms of how radical they are. In this paper, we explore the effec-tiveness of NGO discourses in bringing about social change. We focus on animal advocacy:welfarist NGOs primarily seek to improve the conditions in which animals are raised and re-duce meat consumption, while abolitionist NGOs categorically reject animal use and call fora vegan society. We design an experiment to study the respective impact of welfarist and abo-litionist discourses on participants’ beliefs regarding pro-meat justifications and their actions,namely their propensity to engage in the short-run in animal welfare (charity donation, peti-tion against intensive farming) and plant-based diets (subscription to a newsletter promotingplant-based diets, petition supporting vegetarian meals). We first show that both welfarist andabolitionist discourses significantly undermine participants’ pro-meat justifications. Second,the welfarist discourse does not significantly affect participants’ actions, while we detect a po-tential backlash effect of the abolitionist discourse. We show that the NGOs’ positive standardeffect on actions through the change in beliefs is outweighed by a negative behavioral responseto the discourses (reactance effect). Last, greater public-good contributions are associated withgreater engagement in animal welfare in the presence of an NGO discourse.

Research in economics is anthropocentric. It only cares about the welfare of humans, and usually does not concern itself with animals. When it does, animals are treated as resources, biodiversity, or food. That is, animals only have instrumental value for humans. Yet unlike water, trees or vegetables, and like humans, most animals have a brain and a nervous system. They can feel pain and pleasure, and many argue that their welfare should matter. Some economic studies value animal welfare, but only indirectly through humans’ altruistic valuation. This overall position of economics is inconsistent with the utilitarian tradition and can be qualified as speciesist. We suggest that economics should directly value the welfare of sentient animals, at least sometimes. We briefly discuss some possible implications and challenges for (environmental) economics.

This paper explores the effect of incremental resolution of uncertainty over time on optimal consumption paths. The general model applies to environmental resource consumption in the presence of uncertainty about the size of the resource. What is the effect of the prospect of receiving information in t+1 on consumption in t? The authors show that the effect is positive if, and only if, the marginal utility is convex. This result is valid only if the interest rate is equal to the discount rate of utility, but other cases are also studied. The intuition is that an early resolution of uncertainty allows for a better diversification of risk over time.

Meat consumption has increased significantly in the last 50 years. This trend raises various health and environmental issues, as well as moral concerns regarding farm animal welfare. In this paper, we discuss the regulation of meat consumption in developed countries. Specifically, we discuss possible justifications for this regulation in terms of environmental, health and animal welfare considerations, as well as the effect of fiscal, informational and behavioral regulatory instruments. Finally, we present a list of challenges that policy makers and food scholars may need to confront in the future.

No summary available.

No summary available.

The COVID-19 pandemic reminds us of the importance of health problems at the interface between humans, animals and the environment: nearly two thirds of human infectious diseases come from pathogens shared with wild or domestic animals. While the number of people suffering from infectious diseases is decreasing, especially in Western regions, paradoxically the number of infectious epidemics continues to grow. The role played by the degradation of ecosystems, in particular deforestation, in the phenomenon of "jumping the species barrier" is questioned, as well as, more generally, that of our lifestyles (diets and food chains, trade...). Thus, this pandemic suggests not only to re-evaluate existing public policies of sanitary control and management, but also to see how they should be completed at the level of economic behavior orientation. In order to prevent future epidemics and reduce their impacts, it is important to understand the mechanisms that generate epidemics and the increase in their frequency or severity, and in particular the extent to which global changes and anthropogenic factors modify the situation. If it is difficult, even illusory, to prevent animals from developing diseases that can be transmitted to humans, and if it is necessary to control their appearance and to manage the sanitary and economic consequences, one of the ways to reduce the risks of epidemics would be to act upstream. In this respect, the preservation of natural habitats, the reduction of meat consumption, the reduction of the size of intensive livestock farms and the cessation of the marketing (legal or not) of wild animal meat would constitute coherent and effective measures for tomorrow's "one health" public health policies.

While antispeciesism is an ethical notion, veganism is behavioral. In this paper, we examine the links between the two. Building on Blackorby and Donaldson (1992), we consider a two-species model in which humans consume animals. The level of antispeciesism is conceived as the weight on animals' welfare in the utilitarian social welfare function. We show that more antispeciesism increases meat consumption if and only if animals' utility is positive. That is, the critical condition is whether farm animals' lives are worth living. We then empirically explore this condition using a survey. We find that farm-animal experts and frequent meat eaters are more likely to believe that the lives of farm animals are worth living. We finally discuss some issues in the study of animal welfare in economics and social choice.

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Governments sometimes encourage or impose individual self-protection measures, such as wearing a protective mask in public during an epidemic. However, by reducing the risk of being infected by others, more self-protection may lead each individual to go outside the house more often. In the absence of lockdown, this creates a “collective offsetting effect”, since more people outside means that the risk of infection is increased for all. However, wearing masks also creates a positive externality on others, by reducing the risk of infecting them. We show how to integrate these different effects in a simple model, and we discuss when self-protection efforts should be encouraged (or deterred) by a social planner.

Promoting healthier and more sustainable diets by decreasing meat consumption represents a significant challenge in the Anthropocene epoch. However, data are scarce regarding the effects of nationwide meat reduction campaigns. We described and analyzed the correlates of a national campaign in France (called "Green Monday", GM) promoting the weekly substitution of meat and fish by other nutrients. Two cross-sectional online surveys were compared: a National Comparison sample (NC) of the French general population and a self-selected sample of participants who registered for the Green Monday campaign. A follow-up study was carried out in the GM sample, in which participants were asked during 15 weeks whether or not they had substituted meat and fish. There were 2005 participants aged 18-95 (47.7% females) in the NC sample and 24,507 participants aged 18-95 (77.5% females) in the GM sample. One month after the beginning of the campaign, 51.2% of the respondents reported they had heard about Green Monday in the NC sample, and 10.5% indicated they had already started to apply Green Monday. Logistic regression analysis showed that compared to the NC sample, participants belonging to the GM sample displayed a higher rate of females, Odds Ratio (OR) = 4.26, 95% Confidence Interval (CI): 3.86-4.71, were more educated, OR = 1.32, 95% CI: 1.28-1.36, had higher self-rated affluence, OR = 1.50, 95% CI: 1.42-1.58 and the size of their vegetarian network was greater, OR = 1.50, 95% CI: 1.41-1.58. They reported a slightly higher frequency of meat consumption, OR = 1.05, 95% CI: 1.01-1.10, while their frequency of fish consumption was lower, OR = 0.81, 95% CI: 0.76-0.87. Finally, the personality dimension Openness was more strongly endorsed by participants in the GM sample, OR = 1.79, 95% CI: 1.65-1.93. A multiple regression analysis indicated that Openness also predicted the number of participation weeks in the GM Sample (beta = 0.03, p < 0.009). In conclusion, specific demographic and personality profiles were more responsive to the national campaign, which could inform and help to shape future actions aiming at changing food habits.

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Catastrophe aversion and risk equity are important concepts both in risk management theory and practice. Keeney [Keeney RL (1980) Equity and public risk. Oper. Res. 28(3):527–534] was the first to formally define these concepts. He demonstrated that the two concepts are always in conflict. Yet his result is based on the assumption that individual risks are independent. It has therefore limited relevance for real-world catastrophic events. We extend Keeney’s result to dependent risks and derive the conditions under which more equity and more correlation between two risks imply a more catastrophic situation. We then generalize some of the results for multiple correlated risks.

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Uncertainty is prevalent in policymaking, and is thus an important dimension of policy evaluation and BCA. This chapter introduces the methods and practices to take uncertainty into account in BCA. The pedagogical approach consists in building on the contrast between two related concepts, such as risk versus uncertainty, static versus sequential analysis or ex ante versus ex post BCA.

In this paper, we consider an intergroup contest game with intragroup altruism. We show that more altruism within a group increases conflict intensity by increasing total groups' efforts. Moreover, we show that, unlike the celebrated Olson's group size paradox, group size increases the probability of winning the contest provided that intragroup altruism is high enough.

In this paper, we examine the properties of prediction market prices when risk averse traders have heterogeneous beliefs in state probabilities. We show that the equilibrium state prices equal the mean beliefs of traders about that state if and only if the traders' common utility function is logarithmic. We also provide a necessary and sufficient condition ensuring that the state prices are systematically below or above the mean beliefs of traders, thus providing a rational explanation to the favorite-longshot bias in prediction markets. (C) 2017 Elsevier B.V. All rights reserved.

The social cost of carbon (SCC) is a key tool in climate policy. The SCC expresses in monetary terms the social impact of the emission of a ton of CO2 in a given year. The SCC is calculated using a 'social welfare function' (SWF): a method for assessing social welfare. The dominant SWF in climate policy is the discounted-utilitarian SWF. Individuals' well-being numbers (utilities) are summed, and the values for later generations are reduced ('discounted'). This SWF has been criticized for ignoring the distribution of well-being and including an arbitrary time preference. Here, we use a 'prioritarian' SWF, with no time discount, to calculate the SCC. This SWF gives extra weight ('priority') to worse-off individuals. Prioritarianism is a well-developed concept in ethics and welfare economics, but has been rarely used in climate scholarship. We find substantial differences between the discounted-utilitarian and non-discounted prioritarian SCCs.

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We use a simple consumption model, the so-called cake eating model, to study the interaction of equity, time and risk in social decision making. Total consumption, the "cake", is uncertain. The social planner allocates consumption between two agents (representing two generations), by assigning the first a determinate amount, with the second receiving the risky remainder. We study this consumption allocation decision using three social welfare functions: utilitarianism, ex ante prioritarianism, and ex post prioritarianism. Under standard assumptions, ex ante prioritarianism allocates more consumption to the first generation than utilitarianism. Thus, a concern for equity, in the ex ante prioritarian sense, means less concern for the risky future. By contrast, ex post prioritarianism normally chooses less consumption for the first generation than utilitarianism. We discuss the robustness of these optimal consumption allocations to learning and to more complicated social welfare functions. (C) 2017 Elsevier B.V. All rights reserved.

In this article, we provide an introduction to experimental and quasi-experimental evaluation methods. The objective of these methods is to econometrically identify the causal effects of public policies. We present the concepts and insights using simple numerical examples, supplemented by tables and graphs, without resorting to advanced econometric techniques. We illustrate the discussion with concrete examples, including for example the active solidarity income (RSA) policy, a dam construction project, a vocational training program, and agro-environmental measures. We systematically discuss the main biases and potential problems associated with each method.

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The relationship between wealth and power has long been debated. Nevertheless, this relationship has been rarely studied in a strategic game. In this paper, we study wealth effects in a strategic contest game. Two opposing effects arise: wealth reduces the marginal cost of effort but it also reduces the marginal benefit of winning the contest. We consider three types of contests which vary depending on whether rents and efforts are commensurable with wealth. Our theoretical analysis shows that the effects of wealth are strongly “contest-dependent”. It thus does not support general claims that the rich lobby more or that low economic growth and wealth inequality spur conflicts.

We report on two experiments challenging the common assumption that events with objective probabilities constitute a unique source of uncertainty. We find that, similar to the domain of ambiguity, the domain of risk is rich in the sense that behavior is systematically different when subjects face risky bets based on simple or more complex events. Furthermore, we find a tight association between attitudes toward complex risky bets and attitudes toward both ambiguity and compound lotteries. These results raise questions about the characterization of ambiguity aversion and the modeling of decisions under uncertainty.

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In light of climate change and other global threats, policy commentators sometimes urge that society should be more concerned about catastrophes. This paper reflects on what society's attitude toward low-probability, high-impact events is, or should be. We first argue that catastrophe risk can be conceived of as a spread in the distribution of losses. Based on this conception, we review studies from decision sciences, psychology, and behavioral economics that explore people's attitudes toward various social risks. Contray to popular belief, we find more evidence against than in favor of catastrophe aversion-the preference for a mean-preserving contraction of the loss distribution-and discuss a number of possible behavioral explanations. Next, we turn to social choice theory and examine how various social welfare functions handle catastrophe risk. We explain why catastrophe aversion may be in conflict with equity concerns and other-regarding preferences. Finally, we discuss current approaches to evaluate and regulate catastrophe risk.

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The reference methodological guide in France for the evaluation of public investments recommends a VSL of 3 million euros (Quinet 2013). What does this value mean? Where does it come from? How does it vary according to the characteristics of the population or the risk? How is it used in France, and elsewhere? What are the implications of its use for risk equity? More generally, what are the advantages and limitations of the economic concept of value of life? This article seeks to answer these questions in a simple and brief manner.

Prioritarianism is the ethical view that gives greater weight to well-being changes affecting individuals at lower well-being levels. This view is influential both in moral philosophy, and in theoretical work on social choice-where it is captured by a social welfare function ("SWF") summing a concave transformation of individual well-being numbers. However, prioritarianism has largely been ignored by scholarship on climate change. This Article compares utilitarianism and prioritarianism as frameworks for evaluating climate policy. It reviews the distinctive normative choices that are required for the prioritarian approach: specifying a ratio scale for well-being (if the prioritarian SWF takes the standard "Atkinson" form). determining the degree of concavity of the transformation function (i.e., the degree of social inequality aversion). and choosing between "ex ante" and "ex post" prioritarianism under conditions of risk. The Article also sketches some of salient implications of a prioritarian SWF for climate policy-with respect to the social cost of carbon, the social discount rate, optimal mitigation, and the "dismal theorem." Finally, it discusses the issue of variable population.

The precautionary principle is very popular today. But does it have an economic basis? We present two economic theories of precaution. The first one is based on the classical framework of utility expectation with Bayesian belief revision. The second is based on ambiguity aversion. We discuss the interest, but also the limitations of these two approaches.

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Environmental issues provide a rich ground for identifying the existence and consequences of human limitations. In this paper, we present a growing literature lying at the interface between behavioral and environmental economics. This literature identifies alternative solutions to traditional economic instruments in environmental domains that often work imperfectly. But it also faces a set of challenges, including the difficulty of computing welfare effects, and the identification of a robust environmental policy based on context‐dependent (socio‐) psychological effects. We illustrate our critical discussion with two behavioral schemes that have been widely implemented: “green nudges” and “corporate environmental responsibility.

We examine how different welfarist frameworks evaluate the social value of mortality risk reduction. These frameworks include classical, distributively unweighted cost-benefit analysis--i.e., the "value per statistical life" (VSL) approach-and various social welfare functions (SWFs). The SWFs are either utilitarian or prioritarian, applied to policy choice under risk in either an "ex post" or "ex ante" manner. We examine the conditions on individual utility and on the SWF under which these frameworks display sensitivity to wealth and to baseline risk. Moreover, we discuss whether these frameworks satisfy related properties that have received some attention in the literature, namely equal value of risk reduction, preference for risk equity, and catastrophe aversion. We show that the particular manner in which VSL ranks risk-reduction measures is not necessarily shared by other welfarist frameworks.

In this paper, we provide reviews of recent scientific findings on health effects and preference valuation of health risks related to pesticides, and the role of benefit‐cost analysis in policies related to pesticides. Our reviews reveal that whereas the focus of the health literature has been on individuals with direct exposure to pesticides, e.g. farmers, the literature on preference elicitation has focused on those with indirect exposure, e.g.

In this paper, we derive a set of simple conditions such that ambiguity aversion always raises the demand for self-insurance and the insurance coverage, but decreases the demand for self-protection. We also characterize the optimal insurance design under ambiguity aversion, and exhibit a case in which the straight deductible contract is optimal as in the expected utility model.

The economic theory of decision making under risk has seen remarkable advances over the 50 years since Pratt's (1964) characterization of risk aversion under expected utility. We review developments in three key areas to which Louis Eeckhoudt has made significant contributions: (1) increases in risk and risk taking. (2) self-protection and risk aversion. and (3) higher (and lower) order derivatives of utility. For each, we identify seminal papers, puzzles, and recent developments. The saga of research on these topics reveals that important contributions were made long ago and yet significant gains in understanding continue to be made. Recent advances often have roots in early results and researchers can profit by examining the old as well as the new papers.

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This chapter surveys the economic literature on prevention and precaution. Prevention refers as either a self-protection activity – i.e. a reduction in the probability of a loss – or a self-insurance activity – i.e. a reduction of the loss –. Precaution is defined as a prudent and temporary activity when the risk is imperfectly known. We first present results on prevention, including the effect of risk preferences, wealth and background risks. Second, we discuss how the concept of precaution is strongly linked to the effect of arrival of information over time in sequential models as well as to situations in which there is ambiguity over probability distributions.

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Proper Scoring Rules (PSRs) are popular incentivized mechanisms to elicit an agent's beliefs. This paper combines theory and experiment to characterize how PSRs bias reported beliefs when (i) the PSR payments are increased, (ii) the agent has a financial stake in the event she is predicting, and (iii) the agent can hedge her prediction by taking an additional action. In contrast with previous literature, the PSR biases are characterized for all PSRs and all risk averse agents. Our results reveal complex distortions of reported beliefs, thereby raising concerns about the ability of PSRs to recover truthful beliefs in general decision-making environments.

This thesis reflects on precautionary behavior. Drawing on the definition of the precautionary principle, it examines the optimality of strategies that consist in preventing a risk without waiting for tangible information about it. This new standard of risk management - acting before knowing - is tested against the theory formalized in models of various inspirations. The first three chapters identify the basic economic concepts related to the notion of precaution that exist in the literature. Chapter 1 presents the notion of "prudence". Chapter 2 deals with the value of information. Chapter 3 is devoted to the study of the irreversibility effect. Chapter 4 proposes an application of the precautionary principle to the problem of global warming. We put in scene an agent in charge of deciding the level of CO2 emissions of the society. How does the prospect of receiving new scientific information about the risk of the greenhouse effect alter the optimal emission schedule? To date, studies on this issue have proposed simulation-based analyses. These have largely suggested the postponement of emission reductions. The model presented in this chapter makes it possible to distinguish the different effects involved. If the shape of the utility function is such that the decision-maker is "sufficiently cautious", these effects combine in such a way that they encourage immediate emission reductions, thus providing an economic basis for the precautionary principle. The last two chapters explore precautionary strategies in investment models. Chapter 5 considers the possibility of limiting present consumption for future risky investments. Chapter 6 considers the possibility of investing in an asset with a certain return to protect against financial fluctuations. In these two chapters, we show, as in chapter 4, that the overall effect of information on a sequence of financial decisions is entirely determined by the type of utility function selected.