States have long been understood to have an obligation to protect the international legal rights and interests of others, consistent with the maxim sic utere tuo ut alienum non laedas (use what is yours in such a manner as not to injure that of another). As the world's population becomes more interdependent, this no harm obligation becomes more significant. Further, as knowledge increases about the consequences of human activity for the climate and the environment, the no harm obligation takes on greater relevance vis-à-vis the interests of the Earth's future populations. Future generations’ legal interests have been recognized in the context of sustainable development and through the principle of intergenerational equity. The no harm rule requires that these interests be properly considered and addressed appropriately, commensurate with what is at stake. At a minimum, this may require avoidance of ‘manifestly excessive adverse impacts’.

This article maps the shared legal anatomy of climate and environmental lawsuits, in which plaintiffs claim protection for future generations before domestic or international courts. By closely analyzing the litigation strategies of plaintiffs and the inquiry of courts, the article argues that these proceedings revolve around structurally similar legal standards across domestic and international jurisdictions, which correspond to five normative requirements flowing from the rule of law: namely, respect for human rights, certain quality of law requirements, prohibition of arbitrary exercise of governmental powers, non-discrimination, and access to justice. The cross-jurisdictional analysis shows that courts appear to be increasingly willing to protect future generations against arbitrary treatment by present-day decision makers. The article appraises whether such an intergenerationally sensitive reinterpretation of the rule of law could help to change the short-termist paradigm of environmental and climate law.

This piece addresses Case C-458/19 P before the Court of Justice of the European Union (CJEU) concerning a substance of long-term exposure, namely bis(2-ethylhexyl) phthalate (DEHP). The case concerned the interplay of two complex procedures of European chemical law, namely: the procedure for authorising the use of a substance listed in Annex XIV of Regulation (EC) No 1907/2006 (REACH Regulation); and the procedure for listing a substance in Annex XIV of the REACH Regulation on the basis of its intrinsic properties as a substance of very high concern for the risks it poses, or may pose, to human and environmental health. The significance of this judgment is that it provides a better understanding of how Article 60(4) of the REACH Regulation is interpreted in an analogous manner in relation to other provisions of the same Regulation. Whether DEHP is a question of reproductive toxicity (Article 57(c) of the REACH Regulation) or endocrine-disrupting properties (Article 57(f) of the REACH Regulation), this judgment offers insights into the limits of the CJEU’s willingness and/or ability to use a teleological approach to interpret legislation in this area. Furthermore, this work supports the possibility of applying the principle of intergenerational equity to issues related to long-term exposure such as this one.

We study a stochastic model for a target benefit pension plan suffering from rising longevity and falling fertility. Policies for postponing retirement are carried out to hedge the payment difficulties caused by the aging population. The plan members’ contributions are set in advance while the pension payments reflect intergenerational equity by a target payment level and intergenerational risk sharing by an adjustment. The pension fund is invested in both a risk-free asset and a risky asset. Applying the stochastic optimal control methods, we derive analytic solutions for optimal investment and benefit payment strategies which minimize the benefit risk. Besides, an optimal delayed retirement age which can hedge against the aging phenomenon under certain parameters is given. Therefore, it can provide a basis for quantifying the delay of retirement time.

This article traces the various legal incarnations of the intergenerational equity principle. Despite its silent proliferation in international and constitutional laws over the past five decades, the principle dwelled mostly at the margins of inquiry and practice. Recent efforts to counteract global warming have allowed intergenerational claims to gain new traction. Building on a comparison of ten climate-related lawsuits, I analyze the latest advances in the representation, conceptualization, and remediation of future generations’ interests. Against the backdrop of growing willingness to engage with intergenerational disputes, legal decision makers will need to confront two thorny challenges going forward. Firstly, evolving doctrines of extraterritoriality and legal subjecthood increasingly require the protective scope of the principle to extend to foreign citizens and non-human persons. Secondly, awareness of dispersed and interlocked long-term risks may trigger the application of intergenerational doctrines beyond a narrow environmental frame. Grappling with these challenges implicates larger reflections about the role of law in contriving our collective future.

The German Federal Constitutional Court’s climate decision provides a nuanced acknowledgment of climate change’s constitutional relevance. In this Article, the author critically assesses how the Court innovatively sought to capture the intergenerational equity dimension of climate mitigation through a combination of negative and positive duties stemming from constitutional law. The Article demonstrates how despite progressive findings on intergenerational equity and the innovative invocation of negative duties, the operative part of the decision turned out to be rather limited. Because of remaining uncertainties about the allowable national carbon budget, the Court was unable to require the legislator to enact a stricter reduction path. The author argues that the Court could have narrowed remaining uncertainties, without engaging in judicial activism, by adopting an international and constitutional minimum approach to calculating the national budget and by adjusting the burden of proof. Finally, the Article highlights how the German legislator, by going beyond what was required by the Court “trapped itself” on an ambitious reduction path, opening opportunities for future constitutional complaints.

This paper provides new insights into the effect of birth cohort size on cohort lifetime wages and its sensitivity to the future trajectories of immigration and fertility. The main innovation is to relax the typical assumption of perfect substitution of labor by age. The effect of imperfect substitution of labor by age is to qualify the standard result that smaller birth cohorts are likely to enjoy relatively high wages since that result depends on the size of co-worker cohorts. The positive small cohort effect on lifetime wages therefore depends on demographic patterns, which are simulated here through low and high fertility and immigration projections. The analysis applies to actual and projected cohorts for Australia and tests the sensitivity to alternative demographic parameters, and the substitution and discount parameters. The effects of imperfect substitution can amount several percentage points of lifetime wages.

Attitudes to ageing can predispose decision-making as governments, interest groups and electorates negotiate competing demands in the context of economic constraints and social change. This paper, based on national survey data, investigates change and stability in Australian attitudes to intergenerational equity from 2009–2010 to 2015–2017, alongside concurrent socio-economic and policy change as well as cohort succession. The emphasis is on the baby-boom cohort who are viewed as significant beneficiaries of social change relative to opportunities of younger and older cohorts. Views of older people as a needy group may be changing slightly as more enter later life with substantial wealth and resources. Our results show that there is little perception of intergenerational conflict with the exception of the Millennial cohort whose life chances are compromised by economic and expenditure constraint over the past decade. Overall, attitudes remain sympathetic to older people, especially among women and people rendered vulnerable by poor health, non-home-ownership and low socio-economic positions. The findings do not align with government portrayals of intergenerational inequalities notwithstanding many having negative views of the future and ongoing expenditure restraint strategies. At what appears to be a critical turning point in the life chances of successive cohorts, the findings indicate the interplay between attitudes and social and policy change, as well as implications for social equity and processes of attitudinal change.

In recognition of the intrinsic links between climate change and human rights, many have argued that human rights should play a leading role in guiding state responses to climate change. A group whose human rights will inevitably be affected by climate action (or inaction) today are the members of future generations. Yet, despite their particular vulnerability, future generations so far have gone largely unnoticed in human rights analyses. An adequate response to climate change requires that we recognize and address the human rights consequences for future generations, and consider the legal, practical and theoretical questions involved. This article attempts to answer these questions with a particular focus on the Paris Agreement. It argues that the recognition of state obligations towards future generations is compatible with human rights theory, and that these obligations must be balanced against the duties owed to current generations. The article concludes with a number of suggestions for how this balance could be pursued.

Several areas of welfare economics seek to evaluate states of affairs as a function of interpersonally comparable individual utilities. The aim is to map each state of affairs onto a vector of individual utilities, and then to produce an ordering of these vectors that can be represented by a mathematical function assigning a real number to each. When this approach is used in intertemporal contexts, a central theoretical question concerns the rate of pure time preference, i.e. the evaluative weight to be applied to utility coming at different times. This article criticizes the standard philosophical account of pure time preference, arguing that it ascribes to economists a methodological commitment they need not accept. The article then evaluates three further objections to pure time preference, concluding that it might still be defensible under certain circumstances. I close by articulating a final argument that, if sound, would constitute a decisive objection to pure time preference as it currently figures in much intertemporal welfare economics.

As population demographics shift towards an older population structure in the Western world, concerns about the future costs of pensions are apparent in politics, media and everyday conversations. In New Zealand, the universal state-funded pension paid to all citizens over the age of 65 years is often considered to be unsustainable in the context of population ageing. To examine the arguments surrounding universal superannuation, rhetorical analysis was undertaken on two New Zealand newspaper articles that discussed the future cost of pensions, and the 233 public responses these articles generated. The cost of superannuation was used to emphasise the different characteristics of each generational cohort and the ways that this produced inequity across generations. Claims of intergenerational inequity generated antagonism and widened divisions between generational groups. Foregrounding generational inequity in the discussion of superannuation has profound implications for state-funded income support for older people which relies upon widespread public support. Intergenerational inequity ignores the significant inequity in health and social circumstances in retirement among older New Zealanders and overlooks the significant impact of universal superannuation on protecting older New Zealanders from poverty in later life.

Many critics of economic analysis of climate change impacts and response options claim that information is needed on ecosystem characteristics as well as on economic values to fully inform decisions about how climate change affects human well-being. Information on the irreversibility of impacts also is important, critics argue, because it relates to how society evaluates implications for intergenerational equity. In addition, because climate change is subject to a large degree of Knightian uncertainty, it is useful to understand both the information available for assessing climate change risks, and how individuals themselves perceive and evaluate risks. The paper discusses rationales for using these types of information as important complements to benefit-cost analysis for evaluating climate change risks and responses. Ideally such information could be available in a “dashboard” for decision makers assessing social and economic impacts, although limits on currently available information are a significant barrier to using that approach.

Every game theorist knows of Mertens and Zamir (1985)'s universal beliefs space, which gives deep foundations to Harsanyi's model of Bayesian games, and Kohlberg and Mertens (1986)'s strategic stability, which is the first stone of a complete, axiomatic theory of selection among Nash equilibria. Some French mathematicians refer to the “Mertens–Zamir operator” when using techniques that Mertens and Zamir (1971) introduced to solve a class of repeated games with incomplete information. Readers of Macroeconomic Dynamics may instead have seen Mertens and Rubinchik's 2012 article “Intergenerational Equity and the Discount Rate for Policy Analysis.”

The previous examples give just a slight idea of the scope of Jean-François Mertens's contributions, which also deal with general equilibrium, stochastic games, nonatomic cooperative games, and the strategic foundations of microeconomic theory. In his 2005 MD interview, Robert Aumann says, “A [. . .] person at CORE who has had a tremendous influence on game theory [. . .] is Jean-François Mertens. Mertens has done some of the deepest work in the discipline, some of it in collaboration with Israelis like my students Kohlberg, Neyman, and Zamir; he established a Belgian school of mathematical game theory that is marked by its beauty, depth, and sophistication.” The short interview that follows will definitely not account for the variety and the relevance of Jean-François's research achievements, but is typical of the way in which he talked about his work.

Jean-François asked me to interview him for MD during the spring of 2010. We discussed by e-mail the topics that would be covered and on July 6, 2010, I came to Louvain-la-Neuve with a tape recorder. After lunch, Jean-François suggested that we have coffee on a terrace near the golf course and there, he patiently answered my questions, sometimes in French, sometimes in English, for about two hours. We planned to go on for at least another round but kept postponing the project. . . . When I saw Jean-François for the last time, in February 2012, I gave him the transcript of the July 2010 interview, but he hardly commented on it. He rather told me about an ongoing research article, “A Random Partitions Approach to the Value,” to be presented (by Abraham Neyman) as a “von Neumann lecture” at the World Congress of Game Theory in Istanbul in July 2012. At the same time, he was also completing, with Anna Rubinchik, the revision of a companion paper to the MD article referred to previously (“Equilibria in an Overlapping Generations Model with Transfer Policies and Exogenous Growth,” forthcoming in Economic Theory).

Even if Jean-François did not proofread the transcript that follows, I cannot keep this material for myself. I am confident that those who have known Jean-François will take the interview, even incomplete, as an opportunity to remember his enthusiasm and his patience when he was talking about research. He would often start by identifying holes in obvious or well-known solutions to basic problems, and after a few audacious but illuminating shortcuts, would describe the most surprising achievements in everyday words. I hope that the interview will give an idea of Jean-François's approach to those who did not know him.

Quite naturally, because MD was the planned outlet of the interview, we started by talking about the paper on the discount rate for policy analysis, which was already mentioned in the preceding. Jean-François made a number of informal comments, which usefully complement the MD article. He also explained how this paper led him and his coauthor to undertake a thorough analysis of overlapping generations economies in continuous time. This made a perfect transition to Jean-François's views on general equilibrium theory, his own work in this area, and his early career.

The next step would be Jean-François's meeting with Bob Aumann, who introduced him to game theory. Jean-François pursued Aumann and Maschler's seminal work on infinitely repeated games with incomplete information, mostly with Shmuel Zamir. He went on with the existence of a value in stochastic games, another model of infinitely long games, which was introduced by Shapley in 1953. This research was undertaken with Abraham Neyman at the Institute of Advanced Studies in Jerusalem in 1980. Soon after, Mertens and Zamir started to review and complete all available results on repeated games in order to prepare a reference book on this topic. The material kept growing. Sylvain Sorin joined the team in the nineties and a draft appeared as a 1994 CORE discussion paper. However, in 2010, the book was still unpublished. . . the interview ends up with Jean-François's feelings about the project.

As shown by the list of publications at the end, many important contributions of Jean-François Mertens to game theory and microeconomics are not even mentioned in the interview. During his stay at the Institute of Advanced Studies in Jerusalem in 1980, Jean-François not only worked with Abraham Neyman on stochastic games, but also had his first discussions with Elon Kohlberg on refinements of Nash equilibria. These would be followed by many others, at CORE and Harvard, until the famous Econometrica paper appeared in 1986. For the next 15 years or so, Jean-François further developed the theory of strategic stability, by himself and with his students.

During the same period, Jean-François was also making progress on a completely different problem, the extension of the Shapley value to nonatomic cooperative games. Aumann and Shapley (1974) had made the first steps by proposing a value for smooth games. Jean-François proposed a complete answer to the problem in the eighties and, as already pointed out above, kept working on related topics until the very end.

Even without entering into details, a description of Jean-François's more recent contributions would be beyond the scope of this short introduction. As the interview makes clear, Jean-François became more and more interested in the foundations of microeconomic theory. A typical example is his “limit price mechanism,” which can be loosely described as a double auction with several goods or as an extension of Shapley and Shubik's strategic market games. Another example is “relative utilitarianism,” which, as Jean-François explains in the interview, plays a crucial role in the determination of an appropriate social discount rate for the evaluation of long-term economic policies. Let us listen to him.

For two independent principles of intergenerational equity, the implied discount rate equals the growth rate of real per capita income, say, 2%, thus falling right into the range suggested by the U.S. Office of Management and Budget. To prove this, we develop a simple tool to evaluate small policy changes affecting several generations, by reducing the dynamic problem to a static one. A necessary condition is time invariance, which is satisfied by any common solution concept in an overlapping-generations model with exogenous growth. This tool is applied to derive the discount rate for cost–benefit analysis under two different utilitarian welfare functions: classical and relative. It is only with relative utilitarianism, and assuming time-invariance of the set of alternatives (policies), that the discount rate is well defined for a heterogeneous society at a balanced growth equilibrium, is corroborated by an independent principle equating values of human lives, and equals the growth rate of real per-capita income.