Proliferation of major conventional weapons (MCW) in larger numbers, at greater levels of sophistication, and to more actors is at best a waste of valuable resources and at worst fuel for more and bloodier conflicts. Given a track record of violence, repression, and corruption, norms against exporting weapons to active conflicts and human rights abusers, as well as norms in favor of transparency in weapons transfers, have grown more salient in recent years. Yet international efforts such as the UN Conventional Arms Trade Treaty show little promise for mitigating these ills. This article finds an alternate route toward moderating global arms transfers. It shows, with supporting data, how the United States, pursuing its own political interests, leverages its massive market power to slow the proliferation of dangerous technology, reduce resources spent in the developing world on weapons, stymie the deadweight losses of corruption in the arms industry, and lower the rewards for human rights abusers.

Keeping global temperature rise to within 1.5–2 degrees Celsius above preindustrial levels is looking increasingly unlikely through mitigation alone. While increased adaptation to inevitable climate impacts will be necessary, a new realism is creeping into the climate debate. A growing number of scientists are proposing geoengineering technologies to deal with the expected shortfall, both through carbon dioxide removal and possibly through solar radiation management. But both approaches bring risks and pose significant governance challenges, and would likely affect different communities in different ways. As geoengineering moves mainstream, it is time to put governance at the heart of future discussion, and to broaden the debate from academia to governments, treaty bodies, faith groups, and civic organizations.

The Carnegie Climate Geoengineering Governance Initiative is a major new effort to catalyze this conversation, bringing together players from a wide range of social, geographical, and professional backgrounds. It argues that policymakers need to take an ethical risk management approach, informed by continued research. How should transborder and transgenerational ethical issues be addressed? How will governance frameworks withstand geopolitical change? Can we build on existing international treaties and institutions, or do we need new ones? And most immediately, how should further research on solar engineering be governed—given current plans to start experiments in the stratosphere? In a geoengineered world, who controls the “global thermostat”?

This essay examines the similarities, but even more the dissimilarities, between (nonrevisionist) just war theory and the laws of war. The similarities are obvious: both just war theory and the laws of war distinguish jus ad bellum from jus in bello, and incorporate the principles of distinction, proportionality, and necessity. The dissimilarities derive from the special character of law. Law needs binary, yes-no standards for drawing lines, for example between armed conflict and lesser forms of violence. Laws come in packages (regimes), so that changing only one law is not always practicable. And legal propositions, unlike philosophical propositions, are often detachable from their reasons and applied in unexpected and unwelcome ways. This is especially important in the stresses of battle, when rules of warfare must be usable “off the shelf” by middle- or lower-ranked personnel with no opportunity for bespoke deliberation. The essay provides contemporary illustrations of these differences.

Just war thinking serves a social and psychological role that international law cannot fill. Law is dispassionate and objective, while just war thinking accounts for emotions and the situatedness of individuals. While law works on us externally, making us accountable to certain people and institutions, just war thinking affects us internally, making us accountable to ourselves. Psychologically, an external focus leads to feelings of shame, while an inward focus generates feelings of guilt. Philosophers have long recognized the importance of these two moral emotions. Recently, psychologists have found that feelings of guilt are linked to positive social outcomes, such as the desire for reconciliation and reparation, while shame generates anger and hostility. Just war thinking, as an inward-looking tradition, has a special relationship with guilt. By focusing on moral emotions, just war thinking can move beyond the law in four ways, by developing an ethic of accountability, by providing a foundation for addressing moral injury, by providing a common language for discussing the costs of war, and for identifying ethical problems in radically new contexts.

Just war, international law, and world order are all historically conditioned realities that interrelate with one another in complex ways. This paper explores their historical development and current status while critically examining their interrelationship. It begins with exploring just war as a basic frame for analysis and interconnection with the other two realities. Just war is not an abstract body of moral thought but instead a practically informed morality of war rooted in Christian thought and law, Roman law, and the practice of statecraft. The essay notes the importance of the ideas of jus gentium and jus naturale in just war's fundamental formation, as well as the parallel between its three basic features—sovereign authority, just cause, and the end of peace—and the three goods or ends of politics as classically defined, namely, order, justice, and peace. The essay then moves out to explore the historical and thematic relations between just war tradition and international law, especially the law of war, arguing that these together define a moral and legal structure that is normative for world order. The final section of the paper considers the functioning of the institutions of world order in the context of challenges from rival cultural understandings of war, law, and world order and from the rise of nonstate actors in the international sphere, arguing for dialogical efforts aimed at strengthening both the moral and legal basis for world order against contemporary threats to that order.

Why do we need dialogue between ethical and legal perspectives on norms governing the initiation and conduct of interstate conflict? This essay will examine this question by first critiquing the 2013 Tallinn Manual on the International Law Applicable to Cyber Warfare, which sought to apply existing legal frameworks that govern international violence to a new form of conflict. While the manual is for the most part ethically commendable, the first half of the essay will highlight several of its ethical shortcomings and will then extract general reasons why international law nevertheless must be informed by ethical analysis. The second part of the essay will affirm the importance of law for ethical analyses of justified responses to the burgeoning phenomenon of sublethal harms. While states have always used sublethal harms to weaken adversaries, technological developments have magnified the regularity and effectiveness of these practices, particularly against free societies. Responses to such attacks may include—in addition to defensive countermeasures—punishments that deter and reform, and may target “indirect participants” such as financial supporters. However, determining which responses are ethically justified will require insights gleaned from criminal and tort law.

In the rapidly expanding literature on the ethics of climate engineering, a lot has been made of the fact that stratospheric aerosol injection would for the first time create a world whose climate had been intentionally shaped by deliberate human decisions. Intention has always mattered in ethics. Due to the importance of intention in assigning culpability for harms, one might expect that the moral responsibility for any harms created during an attempt to reconstruct the global climate using stratospheric aerosols would be considerable. This article investigates such an expectation by making a comparison between the culpability for any unintended harms resulting from stratospheric aerosol injection and culpability for the unintended harms already taking place due to carbon emissions. To make this comparison, both types of unintended harms are viewed through the lens of the doctrine of double effect. The conclusion reached goes against what many might expect. The article closes by suggesting that a good way to read this surprising conclusion is that it points toward the continuing moral importance of prioritizing emission reductions.

In his article “Carbon Emissions, Stratospheric Aerosol Injection, and Unintended Harms,” Christopher J. Preston compares the culpability of carbon emitters versus that of geoengineers deploying stratospheric aerosol injection (SAI). This comparison relies on a parallel between carbon emitters and SAI deployers that requires both to be agents. However, both are not. While the harms of geoengineering will be caused by culpable agents acting intentionally, the harms connected to climate change emerge out of the uncoordinated actions of billions of people. Taken as a large group, carbon emitters cause harm but do not constitute an agent. Taken individually, carbon emitters are agents but do not cause the harms of climate change. As a result, the parallel collapses, and Preston's “surprising” conclusion is one that he is not entitled to reach.

In order to advance a neatly deductive argument, Christopher J. Preston must make a number of assumptions and framing decisions that exclude important practical points from the scope of his analysis. We do not criticize him for doing so, as these simplifications allow him to advance a concise argument about an ethically complex subject. However, as scholars of politics and law, we are interested in what this ethical argument means—and does not mean—for the messy politics of climate engineering. Accordingly, in our response we unpack the political implications of some of Preston's assumptions and framing decisions in an effort to add a layer of practical richness to the abstraction of Preston's analysis.

Christopher J. Preston's use of the doctrine of double effect to claim that hypothetical climate engineers might very well be less culpable for climate harms than those who continue to emit greenhouse gases is unpersuasive. His argument rests shakily on the ability to determine and quantify climate harms and to distinguish forensically between their causes. He is also largely silent about the distributional effects of these harms and their ethical and political ramifications.