James Lindley Wilson [Planet Debate evidence release]
[James Lindley Wilson is Collegiate Assistant Professor in the Social Sciences, and Harper Fellow and Collegiate Co-Chair in the Society of Fellows, at the University of Chicago. He received a Ph.D. in Politics from Princeton University in 2011, a J.D. from Yale Law School in 2007, and an A.B. summa cum laude in Social Studies from Harvard University in 2002. He was a policy debater for the Harvard Debate Council and the Lakeland School District in New York, where he was state champion in 1998. He has served as the co-director of the policy division of the Harvard High School Tournament since 2001, and has also directed debate tournaments in New York and Pennsylvania. He regularly lectures at Harvard's Summer Debate Workshops, and in 2012 served as co-director of the NFL-Korea Korea Cup series of speech and debate tournaments in South Korea.]
Perhaps the most immediate questions raised by the October Public Forum resolution is what constitutes “mitigation” of the effects of climate change, and why we might think anyone has an obligation to engage in such mitigation. This paper will address those questions first, and then proceed to more nuanced questions about whether developed countries have such an obligations, and what that might mean. My primary aim in this paper is to provide an analytical framework for organizing debates around this topic, based on the wording of the resolution and my view of the relevant literature in moral and political philosophy and public policy. I will occasionally gesture toward what I believe are the more convincing lines of argument, but my purpose is not to persuade, but instead to give some strategic advice, which of course debaters and coaches might ultimately find unwarranted.
What is mitigation, and why should we mitigate?
Strategies for responding to the prospect of climate change are generally grouped into two broad categories: “mitigation” and “adaptation.” Generally speaking, “mitigation” refers to efforts to prevent the climate from changing (or to limit the extent of change), whereas “adaptation” refers to efforts to respond to a changed climate (see Jamieson 2005). So, for example, efforts to reduce greenhouse gas emissions, and thereby to limit the extent of global temperature rise, are paradigmatic cases of mitigation. By contrast, building barriers around cities to prevent flooding in the event of sea level rise, or investing in different agricultural technologies in light of changes in regional temperatures, represent “adaptation” to a changed climate.
Mitigation and adaptation strategies are generally not mutually exclusive. So, for instance, nations could both attempt to limit the extent of climate change (mitigation) and make preparations to cope with this more limited change (adaptation). Realistically, because the relevant science suggests both that the climate is already changing, and that the world’s emissions patterns “lock us in” to some further climate change no matter what our future mitigation efforts, some adaptation will inevitably be part of any climate policy. The relevant question posed by the resolution, then, is not necessarily whether mitigation should be pursued to the exclusion of adaptation, but whether developed countries have an obligation to mitigate as well as to pursue some adaptation policy. The pro team presumably must argue that some mitigation is obligatory, while the con team could win by arguing that an adaptation-only strategy is sufficient.
Why might anyone on earth have an obligation to mitigate the effects of climate change? The answer must be that unmitigated climate change would be extremely harmful—for instance, in terms of lives lost to starvation, malnutrition, disease, ecosystems collapse, flooding, and so on, lower quality of life due to economic devastation, or whatever other scenarios the best climate science supports. Unfortunately, I do not have the space in this paper to treat climate science debates with the attention they deserve. (There are many good introductions and bibliographic summaries; two good places to start are Gardiner 2010/2004 and Stern 2007.) For the purposes of this topic paper, I will take it for granted that the effects of unmitigated climate change to which we do not adapt would be extreme and severe. (We will discuss in a moment whether unmitigated climate change to which we do adapt is a problem.) As a matter of fact, I believe this assumption is warranted by the science, but I make the assumption in this paper more because it will allow us to proceed to the more complex philosophical and policy debates surrounding the role of mitigation in particular. That said, debaters should be prepared to argue core issues in climate science. This is because “con” teams could potentially win debates on either (1) the claim that unmitigated climate change does not pose any real threats (or at least not enough of a threat to warrant costly efforts to mitigate); or (2) the claim that climate change is not anthropogenic (i.e., caused by human behavior), and so arguably cannot be mitigated by human action. If either of these claims are true, there presumably would be no obligation to mitigate, and so these scientific issues are relevant to debaters. But, again, I do not address them in detail here.
So, again, why would anyone have an obligation to mitigate? Because unmitigated climate change will be harmful. More precisely: the distribution of costs or burdens of unmitigated climate change are more objectionable than the distribution of costs or burdens involved in efforts to mitigate climate change. The language of “distribution” of costs refers to the way in which different costs—whether economic costs or loss of life or anything else—are spread across all people on earth, whether living now or in the future. I speak of “distribution,” rather than simply of the total costs, because arguably the distribution of costs, and not just the total amount, affect our moral obligations (on this much more later). I put the point about obligations to mitigate in this comparative way because any efforts that could plausibly mitigate climate change in any substantial way (for instance, by dramatically decreasing greenhouse gas emissions) certainly will be costly, in economic (and perhaps in other) terms. The pro side must argue that developed countries are obligated to bear these costs in light of the objectionable distribution of costs imposed by unmitigated climate change. The con must argue the opposite—that the costs of mitigation are more objectionable than the costs of an adaptation-only response to climate change, whether because mitigation is extremely costly, or because adaptation is cheap and effective, or both.
Who has the obligation to deal with climate change? Part I: Present and Future
Now that we have some basic ideas in place as to what mitigation is, and why anyone might have some obligation to mitigate, we can proceed to the difficult question of who, if anyone, actually has such an obligation. Remember that in order to establish that developed countries have an obligation to mitigate, it is not enough for pro teams to claim that something must be done about climate change. They must establish that ethical climate policy requires mitigation, as opposed to an adaptation-only strategy. Why might an adaptation-only strategy be preferable? The answer turns on some fairly intuitive points about the costs of mitigation, as well as far less intuitive arguments about the proper distribution of burdens across present and future generations of humanity.
Naturally a central component of the argument against mitigation is that any plausible mitigation effort would be extremely costly. This is a plausible claim, given the substantial changes necessary to move to a lower-carbon economy, though estimates of the costs vary significantly. (For discussion see Gardiner 2010, part IV; Nordhaus 2007; Lomborg 2001.) This observation alone, however, is insufficient to secure a con victory, however; remember that the key comparison is between the distribution of costs involved in a mixture of mitigation and adaptation and the distribution of costs involved in an adaptation-only strategy. One way for the con to argue that the former distribution is worse is to argue that the costs of mitigation are simply massive, and thus that the costs are objectionable no matter how they might be distributed across different individuals. But the con argument for an adaptation-only strategy will be much stronger if it attends to one key difference in how the costs of mitigation and the costs of adaptation will be distributed—that is, the difference in how these costs will be distributed over time.
The most basic point to recognize is that in order to mitigate climate change in any serious way, we need to act now, or in the very near future. (This is a claim about climate science, which I am taking for granted here, as it is generally taken for granted in the literature.) The costs of adaptation, however, need not be borne now, and indeed may primarily be borne in the future—perhaps the far future, generations hence. The reason, very crudely, is that many adaptation strategies will not be implemented until the effects of climate change (hotter summers, more storms, higher sea levels, or whatever) are actually realized. We could, of course, start investing in adaptation now; relative to mitigation, however, the costs of adaptation can be delayed to a very great extent. As a result, it is probably a fair generalization to say that mitigation strategies tend to burden present generations of humanity relative to future generations, whereas adaptation strategies tend to burden future generations relative to those alive today. The question of whether anyone has obligations to mitigate, then, turns to a great degree on whether we have obligations to incur costs today in order to benefit people in the future.
Most conscientious people believe that we should be willing to make sacrifices for future generations—most importantly, of course, for our children and grandchildren, but also more generally for future humanity at large. But is this belief warranted? The answer is (perhaps surprisingly) complicated. It requires us to have some means of comparing impacts that occur at different times—for example, comparing the loss of resources spent today on mitigation efforts with the losses incurred due to unmitigated climate change (even with adaptation) one hundred years from now. One standard way these comparisons are made by economists, philosophers, and scholars of public policy is by what is known as the “discounting” of future costs and benefits. “Discounting” involves giving future costs and benefits less weight in certain respects than similar costs and benefits in the present. So, for example, the loss of one hundred dollars ten years from now is counted as a less serious loss than a loss of one hundred dollars today. The debate about the relative merits of mitigation and adaptation turn largely on how much we should discount future costs and benefits—that is, what the “discount rate” should be—and what, if anything, justifies the choice of a given discount rate. (The clearest discussion I have found is in Broome 2008; see also Stern 2010/2008: 50-53; Nordhaus 2007; Singer 2010/2002: 186.)
Why should we ever think that future costs are less important than present costs? (For simplicity’s sake I’ll refer only to “costs” here, but the logic applies equally to benefits.) One reason might be that we ought to care more about present generations than about future generations—a view sometimes called “temporal partiality,” since it expresses a kind of preference or partiality for people living at one time relative to others living at a different time. The idea is that we should, in our actions, give special weight to those living at the same time as us (or in the very near future), just as, according to some ethical views, we should give special weight to those in our family or to our fellow citizens. In practice, very few people advocate for this kind of temporal partiality; most philosophers (and, I would guess, many non-philosophers) think that everyone should be weighted equally, no matter when they were born. Everyone is equally important: they count equally, and so the costs they suffer should not be discounted. As a result, temporal partiality may not be the best argument for discounting future costs.
A more promising argument for discounting turns on what I call the “richer future” argument. The basic idea is that we should value goods (and therefore costs) in the future less because—assuming worldwide economic growth continues, as seems likely—there will be more goods in the future. Why might this mean we should discount?
One way to think about this argument is to start by recognizing that economic growth effectively means that money today translates (through productive investment) into more money tomorrow (even accounting for inflation). This means that we need to be very careful about small costs today, because the loss of that investment potential translates into large losses tomorrow. For instance, under relatively rosy (but not unreasonable) economic assumptions, one dollar invested today will become two dollars in fifteen years—which means, very roughly, that a given amount of money in fifteen years is about half as valuable as money today. Economists sometimes use private money markets to estimate the proper discount rate, and their results tend to show that the discount rate should be quite steep—that is, we should count future costs much less than present costs (see Nordhaus 2007). The claim that private money market rates provide good evidence for the proper discount rate in policy making is controversial, however, for fairly technical reasons (Stern 2010/2008: 50-53). Debaters probably need not concern themselves with the details, but should try to understand why economic growth and the potential for productive investment gives us reason to err on the side of not “wasting” money on non-productive investments such as climate change mitigation. (I assume here that mitigation policies are not themselves the most productive investments in narrow economic terms. If the pro side can argue that they are, however, this obviously would be to their advantage.)
Another, related way to see why economic growth and the prospect of a richer future supports discounting turns on what economists and philosophers call the principle of “diminishing marginal utility.” The basic idea of this principle is that, for very many goods, the more you have of that good, the less value (or “utility”) you get from having a bit more of that good. So, for example, when all you have in the world is $1,000, you get a lot of extra value (“marginal utility”) out of another $1,000—it adds significantly to your well-being. By contrast, when you have $1,000,000, you get relatively little extra value from having another $1,000—it doesn’t add greatly to your quality of life. So money, like many other goods, generally has diminishing marginal utility.
What does this have to do with discounting? The idea is that if future people are, on average, much richer than we are today, then gaining or losing a certain bundle of goods (like the $1,000 in the example above) would affect their well-being far less than gaining or losing that same bundle of goods would affect us. Put crudely, if future people are richer than present people, they can much more easily afford to make sacrifices than we can (Broome 2008). Under these assumptions, asking the present generation of humanity to sacrifice in order to benefit future generations is like asking a Bangladeshi peasant to donate money to help a rich American buy a second BMW: not only is the sacrifice not morally required, arguably it’s morally objectionable!
Returning more directly to the case of climate policy, the basic result is this: if we assume that economic growth will continue, and the future will be generally richer than the present, then basic marginal utility analysis suggests that we should try to push as many of the costs of climate policy as we can into the future. Recalling that adaptation tends to delay costs relative to mitigation, the “richer future” argument thus suggests that an adaptation-only strategy is morally preferable to a strategy focused on mitigation, as the latter effectively asks the poorer present to sacrifice for the richer future.
How might debaters on the pro side respond to this line of argument against mitigation? First, of course, they might raise doubts about the underlying assumption of continuous economic growth. Long-term growth patterns are hard to predict with confidence, especially when we consider that climate change itself—and the energy policy decisions we make—will likely affect those patterns to a substantial extent (Nordhaus 2010/2008: 50-53—though be warned his argument is not terribly accessible). Second, and more fundamentally, they might make what I call the “expensive future” response to the “richer future” argument. The basic idea is that, while the future may be “richer” in some goods (for instance, because technological innovations make production cheaper), the price of some valuable goods may also increase substantially due to unmitigated climate change. Why would prices increase? Price increases are just a formal way of representing the intuitive idea that it may be difficult (i.e., costly) to secure some important goods—including “goods” such as life and health. If scientists are right to predict that unmitigated climate change will threaten agricultural yields, the sustainability of coastal cities, and so on, this would mean that, for many people, it would take an extraordinary amount of resources to maintain a high level of well-being. In that respect the future would be “expensive.”
Some readers may already see how this rebuts the “richer future” argument. That argument—for relatively steep discounting of future costs, and thus for emphasis on adaptation—relied on the idea that future people would be rich, and so extra resources (e.g., the costs of adaptation) wouldn’t matter much to them. The “expensive future” argument counters that, if climate change is unmitigated, future people will need many more resources than we do to secure the same quality of life—which is to say that extra resources (such as, again, the costs of adaptation) would matter a great deal to them. Accordingly, if this response is adequate, we should not impose costs on future generations, but should make at least some sacrifices on their behalf—including climate change mitigation.
How can debaters arbitrate between the “richer future” and “expensive future” arguments for adaptation and mitigation, respectively? As is so often the case in debates about public policy, the answer lies in the details. Put in abstract terms, the question is which effect is greater: the economic growth and technological innovations that make well-being cheaper and easier to achieve in the future, or the effects of climate change that make well-being increasingly difficult to attain and secure. Predicting these effects with any kind of confidence requires detailed argument about the probabilities of future growth patterns and the probabilities of various effects of climate change, as well as the ease of adapting to those effects. As complicated as debates about these predictions might be, it may seem obvious that debates about obligations to mitigate will turn on our views on how bad climate change might be, how easy it is to adapt, and how we might best use our economic resources. The discussion of discounting and our obligations (if any) to future generations is a way to impose some order on all this complexity—a way to synthesize all of the competing predictions that will appear in a debate round into coherent arguments for mitigation or adaptation. Realistically, given the time constraints of a public forum round, debaters will not be able to present every step of these arguments in detail. I discuss them here, however, in part because the discounting question is one of the most pressing in contemporary debates over climate policy; more relevantly for debaters, however, I discuss these arguments in the hopes that the conceptual framework they provide will help debaters and coaches organize their strategies, and that mastery of this framework will aid debaters in their presentation and their in-round adaptations.
Who has the obligation to deal with climate change? Part II: Countries?
Even if the pro team can successfully argue that people today should mitigate climate change, given the proper understanding of our obligations to future people, questions remain about who specifically among present people has an obligation to undertake the costs of mitigation. The most pressing question, in global politics and in the public forum resolution, is whether developed countries have such an obligation, a question I will discuss in the next section. Here, however, I discuss a separate and seemingly less weighty question, but one that may have some tactical significance in debate rounds: does it make sense to talk of countries having obligations to mitigate?
In thinking about this question, one should recognize that there are alternative obligation-holders (Caney 2010/2005). Perhaps individuals have obligations to mitigate (say, through some mix of individual conservation and through policy advocacy and protest); perhaps obligations fall upon international organizations, or perhaps upon humanity at large. Defenders of the resolution need to be prepared with some reason to think that countries in particular have these obligations.
It is not obvious which side in a debate should win if it were established that the primary obligation holders when it came to climate policy were individuals or international organizations. To some extent the question turns on views about ethics: for instance, if individuals are the primary obligation holders, might it still be true that individuals best act through their governments, and so countries effectively inherit obligations from their individual citizens? To some extent, however, the question turns on rather tricky problems of debate theory: for instance, does the resolution require pro teams to establish that countries are the primary (as opposed to derivative) obligation holders? If the con team establishes that international organizations have the primary obligations, could the pro team still win if they argue that those organizations will not in fact act, and so countries have obligations to fill the gap? These questions of debate theory are beyond the scope of this paper, but I note them for interested competitors and coaches.
In both political practice and, I suspect, the vast majority of public forum debate rounds, it is probably safe to assume that if anyone has obligations to mitigate, countries have such obligations. The reason is the probably obvious one that, given the current state of global politics, countries are the most effective and important actors. International organizations can do very little without the consent of member states; similarly, individuals and transnational groups rarely have significant effect on world events except when they act through states. Accordingly, it is probably reasonable to argue that, as countries are the only actors with the capacity to mitigate climate change to any substantial effect, they are the only actors who could have an obligation to do so.
Before moving on to the vital question of whether developed countries have obligations to mitigate, I will note one further puzzle about the idea of countries in general having such obligations. This puzzle involves problems of collective action. Assuming, as is likely, that mitigation efforts will only be successful if they encompass behavior in most of the globe—that is, if they are part of a global or nearly-global climate policy regime—a question arises about what obligations countries might have if other countries do not make any effort to mitigate. For example, do European countries have an obligation to mitigate given that, as of yet, the United States has made very few serious efforts to mitigate? There are questions of fairness here—are countries obligated to do more than their fair share if other countries are not fulfilling their obligations?—as well as questions of basic efficacy—can countries have obligations to undertake serious costs in what, given the misbehavior of other countries, would be a futile effort to mitigate? In political reality, these are serious, weighty questions, given the notorious difficulties of international environmental cooperation. For purposes of this debate topic, the problem may not be so severe, since the resolution speaks of “developed countries” collectively—a choice which seems to set aside worries about the obligations of one developed country if other developed countries fail to act. That said, there still may be questions about whether developed countries have obligations to mitigate if it is the case that other countries (i.e., developing countries) do not aid in mitigation efforts. If this were to render mitigation by the developed countries futile, it would be difficult to make the case that those countries have an obligation to mitigate. Inaction by developing countries also raises questions about the fairness of imposing obligations on developed countries (as opposed to all countries on earth)—a critical question for debaters on this resolution, and one to which we now turn.
Who has the obligation to deal with climate change? Part III: Developed Countries
As I suggested at the beginning of the previous section, one of the most contentious debates in the context of climate policy involves the question of who, among present people, has an obligation to incur the costs of climate change mitigation. For the purposes of this resolution, pro teams obviously have to establish that developed countries have such obligations. It is worth pausing a moment to ask what exactly this resolutional burden entails. Most importantly, does the resolution require pro teams to establish that developed countries have special or disproportionate or exclusive obligations to mitigate? That is, do they have to argue that developed countries have greater obligations to mitigate than developing countries? Or is it sufficient to establish that developed countries have some obligations to mitigate, whatever obligations other countries might have? On the former interpretation, the pro appears to have a heavier burden. In practice, this question may not matter too much, strategically speaking, because if a pro team is capable of establishing that present generations do have an obligation to mitigate, it may not be a great leap to argue that developed countries will shoulder those obligations to a disproportionate extent, for reasons we will now discuss. But debaters and coaches thinking about their con strategy should consider whether they can gain strategically useful ground by arguing that pro teams have to establish something special about the obligations of developed countries, as opposed to countries in general.
Why might we think that developed countries have special obligations to mitigate? (By “special” I don’t mean anything technical or precise; I just mean to gesture to the idea that developed countries might have more or greater obligations than other countries, however we end up specifying “more” or “greater.”) There are a few prominent ideas in the literature, and I will discuss each briefly. As you will see, however, the validity of any of the following principles is controversial, and working out any of the controversies requires reference to some fundamental issues in ethics—which is to say, more than we can discuss in this paper. I aim here merely to provide you an outline of the main arguments for and against each contending principle.
One of the most popular, and intuitive, arguments for special developed-country obligations to mitigate is known variously as the “polluter pays” principle, or the principle of historical responsibility. The idea is that developed countries are the countries that, to a very great extent, have contributed most to climate change—in particular, because they are responsible for most of the anthropogenic greenhouse gas emissions over the course of human history—and so these countries have a special obligation to undertake costs to limit the harms of climate change. Exactly what the principle requires is complicated, but the general idea is that countries should pay for a climate change regime (presumably including mitigation) in proportion to the amount of greenhouse gases they have emitted over the course of history. The principle appeals to many because it seems in line with our basic intuitions regarding compensation for wrongdoing: those who are responsible for harms have special responsibility for rectifying those harms.
There are problems with using the polluter pays principle to support a climate change regime primarily funded by developed countries, however. First, in some ways the principle is unfair to present generations. Why, they may ask, should we suffer for the sins of our fathers? Talk of the emissions by “countries” seems to ignore the crucial fact that the ones who did much of the emitting—previous generations—are different from those whom the principle asks to pay for rectification. This difference between those who polluted and those who pay might undermine our confidence that the principle is supported by basic intuitions about compensation for harm (because compensation assumes the wrongdoer and the compensator are the same). There may be ways to respond adequately to this objection—perhaps by pointing out that current generations benefit, through greater national wealth, from the pollution of their forebears—but the objection unquestionably complicates matters. A second objection to the polluter pays principle involves the claim that, before some fairly recent point—say, 1980 or 1990—it was not widely known (and could not have been widely known, even to conscientious people) that greenhouse gas emissions were harmful. It is unfair, the objection goes, to hold people responsible harms that they could not possibly have known they were causing. People may differ on whether this ignorance excuse is persuasive. In any case, it is worth noting that neither of these objections necessarily absolve developed countries of all obligations to support a climate policy—the objections leave untouched those countries’ obligations for recent, current, and ongoing emissions. Nevertheless, the objections may, if successful, seriously limit developed countries’ obligations, perhaps enough even to make a successful climate regime impossible without substantial developing-country cooperation.
A second influential argument for develop countries’ obligations to support a climate regime rests on what is often called the “ability to pay” principle. The principle argues that the costs should be distributed according to who can afford to pay those costs, which in practice means, of course, that richer countries should incur most of the costs of a climate policy. (Exactly how much depends on how progressive the “ability to pay” principle is.) Probably the most powerful consideration on behalf of this principle is that it squarely acknowledges that poorer countries should not have to sacrifice fundamental development goals—that is, improving the health, freedom, and well-being of their citizenry—in order to prevent a problem that they largely did not cause. One major problem with this principle, however, is that it has nothing, really, to do with climate change. The principle appears arbitrary unless it is grounded on some more basic principle of global distributive justice, which would explain why rich countries should pay more to solve global problems. This, again, is not to say that the principle is wrong, but just to say that it cannot be very persuasive without some background argument for the supporting principles of justice.
A third and final major approach to distributing the costs of climate policy worldwide is called the “equal per capita shares” approach. This approach requires a bit more explanation than the prior two. Proponents of this approach first suggest that we think of the atmosphere as a kind of “sink” that can tolerate only so many greenhouse gas emissions before disaster strikes. We can put a rough number on this amount of tolerance—for example, in terms of how many more tons of carbon emissions the atmosphere can tolerate—and then split up this amount equally among all people on earth. (So, for example, if climate science tells us we can tolerate only 500 billion more metric tons of carbon than we currently have in the atmosphere, we split up the rights to 500 billion metric tons’ worth of emissions equally among every individual on earth.) Then a climate regime should be put in place allowing countries to emit as much carbon as their populations’ collective entitlements allow. Countries that wished to emit more than their rights allowed would either purchase rights from other countries, or would pay penalties to some fund to be used to support the climate regime. I am obviously ignoring enormous institutional complexities here, but I hope the basic idea is clear enough.
The equal-shares approach has the benefit of recognizing that nobody has a special right to natural resources (like the atmosphere’s absorptive capacity), and that merely taking such resources by force does not necessarily give one an entitlement to those resources, or to the gains from such resources (Beitz 1999: Part III). This is a deeply egalitarian insight, and thus is very appealing to many who hold relatively egalitarian views about justice and property. On the other hand, this approach to climate policy faces serious difficulties (even apart from any general criticisms of egalitarianism). First, if emissions are split up “going forward,” as in my example above—that is, if we equally split up the remaining absorptive capacity of the atmosphere, starting now—it will give developing countries very few emissions rights. (This is largely because there just aren’t that many rights to go around any more.) This would cause those poorer countries to suffer substantial economic losses. More generally, the problem is that the principle fails to recognize fundamental development goals, and fails to distinguish between different purposes of emissions—purposes that have very different degrees of moral urgency. (For instance, it is more important to preserve emissions that help countries avoid mass poverty than it is to preserve emissions that help countries preserve a high level of luxury [Shue 2010/1993].) Second, however, if emissions are split up across all of human history—that is, we split up the total amount of emissions that would take the earth all the way from natural levels to the danger threshold—and then debit countries for their historical emissions, we effectively would have something close to the “polluter pays” principle, with all of the potential objections that principle faces. As a result, the equal-shares approach, as promising and sophisticated as it may seem, appears not to integrate the full range of moral concerns relevant to climate policy.
As I suggested at the beginning of the last section, the question of whether developed countries have a special obligation to mitigate is very complicated. My own view is that it is probably futile to try to develop a special theory of climate policy justice; instead, figuring out what our obligations are with respect to climate policy requires us to refer to some more general framework of global justice—that is, a general theory of what we owe to each other in global politics. This theory may be as simple as the idea that we ought always act so as to maximize the good consequences of our actions, even when the beneficiaries are citizens of other countries (Singer 1972), or it may involve a complex argument about fairness in global economic distribution (Beitz 1999, Part III). Arguments about climate policy obligations would then follow from more general principles explaining what, if anything, the rich owe to the poor and vulnerable.
Is that conclusion of any help to public forum debaters on this topic? In one sense, no, because it is not realistic for debaters to engage in detailed debates about the abstract foundations of global justice and to address the implications of those foundations for climate policy in very time-constrained speeches. In another sense, though, the conclusion may be helpful, if it reminds debaters and coaches to prepare some time-efficient sketch of a general moral argument that supports their positions in a given debate round. It may be that in many rounds debaters will not need to make even these sketches explicit, as the rounds will turn on issues in climate science or the relative benefits of adaptation and mitigation. But the ability to refer to such ethical frameworks when called upon, and—perhaps more importantly—the ability to understand these frameworks and how they make one’s arguments hang together coherently, even if one is not called upon to explain the frameworks explicitly in a round, may substantially increase debaters’ persuasiveness.
 Many perceptive readers will think that this discounting can be explained by inflation—i.e., that the hundred dollars in the future will be worth less, in real terms, than one hundred dollars today, assuming that we experience net inflation in the next ten years. Discounting is indeed used to account for inflation, but for the purposes of this discussion we should set aside questions about inflation and nominal pricing. There is a remaining, very important question about whether we should discount costs and benefits in the future in real terms—that is, even apart from inflation. Similarly, some readers might wonder if discounting can be explained entirely by reference to probability—for instance, we count future costs for less because we might not be around to experience them. (We might die before ten years are out, alas.) Probability is relevant in the climate case (including the probability of extinction of the human species, the analog of death in the individual case), but, again, there remain other, central questions about how we should value future costs or benefits apart from questions about their probability.
 The argument here turns on the traditional ethical maxim, “ought implies can.” That is to say, one may only say that an actor ought to do a given act if that actor can do that act. One cannot be obliged to do something that is impossible.
The most essential reference is the aptly titled Gardiner, Stephen M. et al., eds. 2010. Climate Ethics: Essential Readings. Oxford: Oxford University Press.
Beitz, Charles R. 1999. Political Theory and International Relations (3rd ed.). Princeton: Princeton University Press.
Broome, John. 2008. “The Ethics of Climate Change,” Scientific American 298, 6: 97-102.
Caney, Simon. 2010/2005. “Cosmpolitan Justice, Responsibility, and Global Climate Change,” in Leiden Journal of International Law; reprinted in Gardiner et al. 2010.
Gardiner, Stephen M. 2010/2004. “Ethics and Global Climate Change,” Ethics 114: 555-600; reprinted in Gardiner et al. 2010.
Jamieson, Dale. 2005. “Adaptation, Mitigation, and Justice,” in Perspectives on Climate Change: Science, Economics, Politics, Ethics. Advances in the Economics of Environmental Resources 5: 217-48.
Lomborg, Bjørn. 2001. “Global Warming,” in The Sceptical Environmentalist. Cambridge: Cambridge University Press: 258-324.
Nordhaus, William. 2007. “Critical Assumptions in the Stern Review on Climate Change,” Science 317: 311-12.
Shue, Henry. 2010/1993. “Subsistence Emissions and Luxury Emissions, Law & Policy 15, 1: 39-59; reprinted in Gardiner et al. 2010.
Singer, Peter. 1972. “Famine, Affluence, and Morality,” in Philosophy & Public Affairs 1: 229-43.
Singer, Peter. 2010/2002, “One Atmosphere,” in Singer, One World: The Ethics of Globalization. New Haven: Yale University Press.
Stern, Nicholas. 2007. The Economics of Climate Change (the “Stern Review”), Executive Summary, pp. 1-57.
Stern, Nicholas. 2010/2008. “The Economics of Climate Change,” American Economic Review 98: 1-37; reprinted in Gardiner et al. 2010.