Mark Budolfson

Choosing a policy response to climate change seems to demand a population axiology. A formal literature involving impossibility theorems has demonstrated that all possible approaches to population axiology have one or more seemingly counterintuitive implications. This leads to the worry that because axiological theory is radically unresolved, this theoretical ignorance implies serious practical ignorance about what climate policies to pursue. This chapter offers two deflationary responses to this worry. First, it may be that given the actual facts of climate change, all axiologies agree on a particular policy response. In this case, there would be a clear dominance conclusion, and the puzzles of axiology would be practically irrelevant (albeit still theoretically challenging). Second, despite the impossibility results, the authors prove the possibility of axiologies that satisfy bounded versions of all of the desiderata from the population axiology literature, which may be all that is needed for policy evaluation.

In this chapter, Mark Budolfson and Dean Spears analyse the marginal effect of philanthropic donations. The core of their analysis is the observation that marginal good done per dollar donated is a product (in the mathematical sense) of several factors: change in good done per change in activity level of the charity in question, change in activity per change in the charity’s budget size, and change in budget size per change in the individual’s donation to the charity in question. They then discuss the “hidden zero problem” that some of the terms in the equation (in particular, the last term) might be “hidden zeros” that prevent donations from doing any good—or worse, imply that they do harm—even if the charity is at the top of effective altruism rankings based on the other factors.

This chapter raises objections to the argument that a highly unjust response to the problem of climate change is the best that we can currently hope for and is thus the solution that we should actively promote even from an ethical point of view. Such an argument has been put forward by a wide range of commentators in philosophy, economics, law, and international affairs including John Broome, Eric Posner, David Weisbach, and Cass Sunstein. Among other things, the author argues that the way in which this argument fails is both ethically and practically instructive, as its failure reveals how a realist approach to climate policy is consistent with a more equity-focused approach than is commonly appreciated. As a concrete illustration, it is explained how the lessons could be incorporated into a more ethical climate treaty architecture that shares structural features with proposals from William Nordhaus, Joseph Stiglitz, and others.

Climate change is poised to threaten, disrupt, and transform human life, and the social, economic, and political institutions that structure it. In light of this, understanding climate change, and discussing how to address it, should be at the very center of our public conversation. Philosophy can make an enormous contribution to that conversation, but only if both philosophers and non-philosophers understand what it can contribute. The sixteen original articles collected in this volume both illustrate the diverse ways that philosophy can contribute to this conversation, and ways in which thinking about climate change can help to illuminate a range of topics of independent interest to philosophers.

Future population growth is uncertain and matters for climate policy: higher growth entails more emissions and means more people will be vulnerable to climate-related impacts. We show that how future population is valued importantly determines mitigation decisions. Using the Dynamic Integrated Climate-Economy model, we explore two approaches to valuing population: a discounted version of total utilitarianism (TU), which considers total wellbeing and is standard in social cost of carbon dioxide (SCC) models, and of average utilitarianism (AU), which ignores population size and sums only each time period’s discounted average wellbeing. Under both approaches, as population increases the SCC increases, but optimal peak temperature decreases. The effect is larger under TU, because it responds to the fact that a larger population means climate change hurts more people: for example, in 2025, assuming the United Nations (UN)-high rather than UN-low population scenario entails an increase in the SCC of 85% under TU vs. 5% under AU. The difference in the SCC between the two population scenarios under TU is comparable to commonly debated decisions regarding time discounting. Additionally, we estimate the avoided mitigation costs implied by plausible reductions in population growth, finding that large near-term savings ($billions annually) occur under TU; savings under AU emerge in the more distant future. These savings are larger than spending shortfalls for human development policies that may lower fertility. Finally, we show that whether lowering population growth entails overall improvements in wellbeing—rather than merely cost savings—again depends on the ethical approach to valuing population.

If one rejects choice theory, one still faces the challenge of explaining what one should do in a self-torture case if one is fully rational, and why. In addition, one faces the more fundamental challenge of explaining what rationality is, if it is not choice theory. Responding to these challenges in a systematic way is one of several key contributions of Andreou’s insightful book Choosing Well, and is my focus here as well. My goal is to highlight questions that arise for Andreou’s view, especially from the perspective of those who are sympathetic to choice theory.

Transparency and openness are broadly endorsed in energy and environmental modelling and analysis, but too little attention is given to the transparency of value-laden assumptions. Current practices for transparency focus on making model source code and data available, documenting key equations and parameter values, and ensuring replicability of results. We argue that, even when followed, these guidelines are insufficient for achieving deep transparency, in the sense that results often remain driven by implicit value-laden assumptions that are opaque to other modellers and researchers, and that may not be understood by wider audiences to be controversial. This paper identifies additional best practices for achieving transparency by highlighting issues where disagreement over value judgements will persist for the foreseeable future. Recommendations for deepening transparency are developed by learning from successes and ongoing challenges represented in three case studies. We provide recommendations to accelerate the adoption of additional best practices for deepening transparency of energy and environmental modelling in policy-relevant domains, increasing stakeholder participation with non-modellers, and encouraging interdisciplinary dialogue.

Many political theorists take the phenomenon of market failure to show that arguments for libertarianism fail in a straightforward way. This chapter explains why the most common form of this objection depends on invalid reasoning, and why a more sophisticated examination of the relevant economics has led most contemporary economists and policy experts to a view that might be called Default Libertarianism, according to which the strong default for public policy—even in response to market failures—should be toward decentralized, pro-individual freedom policies that involve minimal government intervention in markets. Some experts (but by no means all) similarly believe that even in the face of substantial market failures, libertarian policies are generally best all things considered. This shift toward more libertarian policy represents an important change from the middle of the twentieth century. This chapter explains the structure of the arguments that have led to this shift.

A standard view in legal and political theory is that, to a first approximation, (1) we should aim to bring about the most legitimate institutions possible to solve the problems that should be solved at the level of politics, and (2) individual people are required to follow the directives of legitimate institutions, at least insofar as those institutions have the authority to issue those directives, and insofar as other considerations are nearly equal.1 On this standard view, the philosophical analysis of institutional legitimacy can appear to be of the utmost importance because it can seem to answer the most important questions about what we should actually do in the realm of law and politics, and because it may also seem to serve as the crucial bridge between ideal and nonideal theory, at least if institutional legitimacy is analyzed as it often is as a matter of doing well enough along dimensions that are familiar from ideal APA NEWSLETTER | PHILOSOPHY AND LAW theory (e.g., ideal justice, universal consent, respecting basic rights, social welfare maximization, and so on). In what follows I identify a number of possible counterexamples to this standard view, which suggest that there may be no straightforward connection between institutional legitimacy and facts about what reasons, rights, and duties we actually have, and what institutions we should actually try to bring about, contrary to what the standard view assumes.

Many philosophers endorse utilitarian arguments against eating meat along the lines of Peter Singer’s, while others endorse deontological arguments along the lines of Tom Regan’s. This chapter suggests that both types of arguments are too quick. Empirical reasons are outlined for thinking that when one eats meat, that doesn’t make a difference to animals in the way that it would have to for either type of argument to be sound—and this chapter argues that this is true notwithstanding recent “expected utility” arguments to the contrary. The chapter then identifies a general puzzle: given that almost everything we do in modern society has some footprint of harm, how does one properly distinguish acts that are permissible among these from those that are not? The chapter explains why this is more difficult than it may initially appear, and it proposes a solution.

If non-human animals experience wellbeing and suffering, such welfare consequences arguably should be included in a social welfare evaluation. Yet economic evaluations almost universally ignore non-human animals, in part because axiomatic social choice theory has failed to propose and characterize multi-species social welfare functions. Here we propose axioms and functional forms to fill this gap. We provide a range of alternative representations, characterizing a broad range of possibilities for multi-species social welfare. Among these, we identify a new characterization of additively-separable generalized (multi-species) total utilitarianism. The multispecies setting permits a novel, weak species-level separability axiom with important consequences. We provide examples to illustrate that non-separability across species is implausible in a multi-species setting, in part because good lives for different species are at very different welfare levels. Finally, we explore the consequences for evaluating climate policy and understanding speciesism and non-climate environmental goals, such as biodiversity.

What are the prospects for using population policy as tool to reduce carbon emissions? In this paper, we review evidence from population science, in order to inform debates in population ethics that, so far, have largely taken place within the academic philosophy literature. In particular, we ask whether fertility policy is likely to have a large effect on carbon emissions, and therefore on temperature change. Our answer is no. Prospects for a policy of fertility-reduction-as-climate-mitigation are limited by population momentum, a demographic factor that limits possible variation in the size of the population, even if fertility rates change very quickly. In particular, a hypothetical policy that instantaneously changed fertility and mortality rates to replacement levels would nevertheless result in a population of over 9 billion people in 2060. We use a leading climate-economy model to project the consequence of such a hypothetical policy for climate change. As a standalone mitigation policy, such a hypothetical change in the size of the future population-much too large to be implementable by any foreseeable government programme-would reduce peak temperature change only to 6.4°C, relative to 7.1°C under the most likely population path. Therefore, fertility reduction is unlikely to be an adequate core approach to climate mitigation.

Nearly all large policy decisions influence not only the quality of life for existing individuals but also the number-and even identities-of yet-to-exist individuals. Accounting for these effects in a policy evaluation framework requires taking difficult stances on concepts such as the value of existence. These issues are at the heart of a literature that sits between welfare economics and philosophical population ethics. Despite the inherent challenges of these questions, this literature has produced theoretical insights and subsequent progress on variable-population welfare criteria. A surprisingly bounded set of coherent alternatives exists for practitioners once a set of uncontroversial axioms is adopted from the better-studied welfare criteria for cases where populations are assumed to be fixed. Although consensus has not yet been reached among these remaining alternatives, their recommendations often agree. The space has been sufficiently restricted and well explored that applications of the theoretical insights are possible and underway in earnest.

The population ethics literature has long focused on attempts to avoid the repugnant conclusion. We show that a large set of social orderings that are conventionally understood to escape the repugnant conclusion do not in fact avoid it in all instances. As we demonstrate, prior results depend on formal definitions of the repugnant conclusion that exclude some repugnant cases, for reasons inessential to any "repugnance" (or other meaningful normative properties) of the repugnant conclusion. In particular, the literature traditionally formalizes the repugnant conclusion to exclude cases that include an unaffected sub-population. We relax this normatively irrelevant exclusion, and others. Using several more inclusive formalizations of the repugnant conclusion, we then prove that any plausible social ordering implies some instance of the repugnant conclusion. This understanding-that it is impossible to avoid all instances of the repugnant conclusion-is broader than the traditional understanding in the literature that the repugnant conclusion can only be escaped at unappealing theoretical costs. Therefore, the repugnant conclusion provides no methodological guidance for theory or policy-making, because it does not discriminate among candidate social orderings. So escaping the repugnant conclusion should not be a core goal of the population ethics literature.

Reducing greenhouse gas emissions has the 'co-benefit' of also reducing air pollution and associated impacts on human health. Here, we incorporate health co-benefits into estimates of the optimal climate policy for three different climate policy regimes. The first fully internalizes the climate externality at the global level via a uniform carbon price (the 'cooperative equilibrium'), thus minimizing total mitigation costs. The second connects to the concept of 'common but differentiated responsibilities' where nations coordinate their actions while accounting for different national capabilities considering socioeconomic conditions. The third assumes nations act only in their own self-interest. We find that air quality co-benefits motivate substantially reduced emissions under all three policy regimes, but that some form of global cooperation is required to prevent runaway temperature rise. However, co-benefits do warrant high levels of mitigation in certain regions even in the self-interested case, suggesting that air quality impacts may expand the range of possible policy outcomes whereby global temperatures do not increase unabated.

This paper asks about the climate damages that Indian policymakers can expect. What is the likely magnitude of climate damages, and how sensitive are they to the level of warming? How much worse would climate damages be for Indians under, say, 5° of warming rather than 3°? Understanding the magnitude of climate damages and how rapidly they increase as temperature change increases is critical for finding the right climate mitigation policy. This paper provides projections of India’s climate vulnerability on the basis of new microeconomic and macroeconomic evidence. The authors’ quantifications show that India is highly vulnerable to climate damage. Their baseline macroeconomic approach suggests that climate change peaking at 5°C, rather than 3°C, would be as detrimental to Indian well-being as a reduction in GDP by about 18 percent for each of the years from 2020 to 2040. Such an equivalent threat to near-term economic outcomes would be an overriding policy priority if political leaders anticipated it. The authors’ microeconomic results suggest that this may be an underestimate, because it ignores humidity. Emerging evidence suggests that humans are especially vulnerable to exposure to high temperatures in contexts of high humidity; humidity is a previously underappreciated and unquantified reason way in which India may be more climate-vulnerable even than some hotter developing and middle-income countries.

The focus of this chapter is public policy and consequentialism, especially issues that arise in connection with the environment – i.e. the natural world, including non-human animals. We integrate some of the existing literature on environmental economics, welfare economics, and policy with the literature on environmental values and philosophy. The emphasis on environmental policy is motivated by the fact that it is arguably the most philosophically interesting and challenging application of consequentialism to policy, as it includes all the challenges of valuing the distribution of human wealth and power, and has the further challenge of putting these consequences on the same scale as consequences for human health, non-human animals, and nature. We suggest that standard methods of (economic) policy analysis provide a good approximation of correct welfarist analysis, except that they must be supplemented with methods for valuing animal wellbeing and tradeoffs with human wellbeing. We then provide the needed methods.

Deciding which climate policies to enact, and where and when to enact them, requires weighing their costs against the expected benefits. A key challenge in climate policy is how to value health impacts, which are likely to be large and varied, considering that they will accrue over long time horizons (centuries), will occur throughout the world, and will be distributed unevenly within countries depending in part on socioeconomic status. These features raise a number of important economic and ethical issues including how to value human life in different countries at different levels of development, how to value future people, and how much priority to give the poor and disadvantaged. In this article we review each of these issues, describe different approaches for addressing them in quantitative climate policy analysis, and show how their treatment can dramatically change what should be done about climate change. Finally, we use the social cost of carbon, which reflects the cost of adding carbon emissions to the atmosphere, as an example of how analysis of climate impacts is sensitive to ethical assumptions. We consider $20 a reasonable lower bound for the social cost of carbon, but we show that a much higher value is warranted given a strong concern for equity within and across generations.

Tools are needed to benchmark carbon emissions and pledges against criteria of equity and fairness. However, standard economic approaches, which use a transparent optimization framework, ignore equity. Models that do include equity benchmarks exist, but often use opaque methodologies. Here we propose a utilitarian benchmark computed in a transparent optimization framework, which could usefully inform the equity benchmark debate. Implementing the utilitarian benchmark, which we see as ethically minimal and conceptually parsimonious, in two leading climate–economy models allows for calculation of the optimal allocation of future emissions. We compare this optimum with historical emissions and initial nationally determined contributions. Compared with cost minimization, utilitarian optimization features better outcomes for human development, equity and the climate. Peak temperature is lower under utilitarianism because it reduces the human development cost of global mitigation. Utilitarianism therefore is a promising inclusion to a set of benchmarks for future explorations of climate equity.

Existing estimates of optimal climate policy ignore the possibility that carbon tax revenues could be used in a progressive way; model results therefore typically imply that near-term climate action comes at some cost to the poor. Using the Nested Inequalities Climate Economy (NICE) model, we show that an equal per capita refund of carbon tax revenues implies that achieving a 2 °C target can pay large and immediate dividends for improving well-being, reducing inequality and alleviating poverty. In an optimal policy calculation that weighs the benefits against the costs of mitigation, the recommended policy is characterized by aggressive near-term climate action followed by a slower climb towards full decarbonization; this pattern—which is driven by a carbon revenue Laffer curve—prevents runaway warming while also preserving tax revenues for redistribution. Accounting for these dynamics corrects a long-standing bias against strong immediate climate action in the optimal policy literature.

At first glance, it may seem that climate policy based on estimates of the social cost of carbon (SCC) presupposes a set of controversial assumptions, especially about what detailed knowledge regulators have about the impacts of climate change, and what the proper role of government and policy is in responding to those impacts. However, I explain why the SCC-based approach need not actually have these problematic presuppositions as well as why SCC estimates may provide the best guide to climate policy when implemented in a way that incorporates a healthy dose of humility. The SCC-based approach can be used in a way that is ecumenical between the wide range of reasonable but incompatible views about the proper goals of government and policy, ranging from views that aim only at market-efficiency, to utilitarian views, to rights-based and other deontological views, to libertarian views, to virtue ethics views, and others. Beyond this, I suggest that the SCC-based approach can help us find an overlapping consensus on a particular climate policy given the range of reasonable but incompatible normative views endorsed in diverse societies. Finally, I consider a number of specific objections to the SCC-based approach that are especially prominent in contemporary discourse and policy debates. I suggest that even if we agree that all of these objections to existing SCC-based analyses have an important kernel of truth, nonetheless the correct response to climate change still involves substantial emissions reductions to be achieved via policy, and the best methods for deciding the magnitude of those reductions still depend essentially on the SCC-based approach.

Discourse on food ethics often advocates the anti-capitalist idea that we need less capitalism, less growth, and less globalization if we want to make the world a better and more equitable place. This idea is also familiar from much discourse in global ethics, environment, and political theory, more generally. However, many experts argue that this anti-capitalist idea is not supported by reason and argument, and is actually wrong. As part of the roundtable, “Ethics and the Future of the Global Food System,” the main contribution of this essay is to explain the structure of the leading arguments against this anti-capitalist idea, and in favor of well-regulated capitalism. I initially focus on general arguments for and against globalized capitalism. I then turn to implications for the food, environment, climate change, and beyond. Finally, I clarify the important kernel of truth in the critique of neoliberalism familiar from food ethics, political theory, and beyond—as well as the limitations of that critique.