¹ Quinn, Warren S., “Actions, Intentions, and Consequences: The Doctrine of Double Effect,” Philosophy and Public Affairs 18, no. 4 (1989), pp. 334–51Google ScholarPubMed.

² Ibid. See also Alison McIntyre, “Doctrine of Double Effect,” Stanford Encyclopedia of Philosophy [2004] (2014), plato.stanford.edu/entries/double-effect/; Quinn, Warren S., “Reply to Boyle's Who is Entitled to Double Effect?” Journal of Medicine and Philosophy 16, no. 5 (1991), pp. 511–14CrossRefGoogle ScholarPubMed.

³ I have expressed doubts about the moral status of geoengineering in Currie, Adrian and Lawford-Smith, Holly, “Accelerating the Carbon Cycle: The Ethics of Enhanced Weathering,” Biology Letters 13, no. 4 (2017)Google Scholar [early view].

⁴ See also Heede, Richard, “Tracing Anthropogenic Carbon Dioxide and Methane Emissions to Fossil Fuel and Cement Producers, 1854–2010,” Climatic Change 122, no. 1–2 (2014), pp. 229–41CrossRefGoogle Scholar. Heede traces nearly two-thirds of historical emissions of carbon dioxide and methane to just ninety corporate entities. Most of these corporate entities are investor owned, but some are state or nation-state owned. Still, that is not the same as the emissions being produced by the state or nation-state itself, because the corporation will be a collective agent in its own right. The division of responsibility would depend on the exact nature of the relationship between the two (absolute control, editorial control, mere advising, etc.).

⁵ Working out the causation of greenhouse gases is actually far from straightforward. First, we get different answers depending on whether we use a theory of causation as production or a theory of counterfactual causation. Take car emissions, for example. The production theory implicates drivers (end-consumers), while the counterfactual theory implicates car manufacturers (without which the drivers could not have driven). Second, the complete causal explanation of any specific emissions may include many agents. For example, when an individual drives a car she is the one who has decided to drive and thereby to burn fossil fuels; but many others were involved in producing the car parts, building and shipping the car, selling the car, and likewise in sourcing, refining, and transporting the fossil fuels. A web of many different individuals and collectives contributes to global emissions. Governments are part of this web to the extent that they own some of the public facilities that produce emissions, such as national rail and electricity companies, and to the extent that they make policy that constrains the actions of others in the web, such as decisions about investment in public transport infrastructure or subsidies for clean energy enterprises. This complicates the causal picture, but it still does not make governments major emitters (and if they are only minor emitters, it is not clear why they should be singled out in the way Preston does). See also Roser, Dominic and Tomlinson, Luke, “Trade Policies and Climate Change: Border Carbon Adjustments as a Tool for a Just Global Climate Regime,” Ancilla Iuris, Special Issue: International Law and Ethics (2014), pp. 223–45Google Scholar, particularly section V; and Steininger, Karl et al. , “Justice and Cost Effectiveness of Consumption-Based Versus Production-Based Approaches in the Case of Unilateral Climate Policies,” Global Environmental Change 24 (2014), pp. 75–87 CrossRefGoogle Scholar, particularly section II. I am grateful to Anton Eriksson and Dominic Roser for discussion on this point.

⁶ The DDE is meant to cover cases of known, or highly probable, incidental effects (for examples, see McIntyre [2014]). In Philippa Foot's classic discussion, DDE provides a way to vindicate flipping the switch in the Trolley Problem when this is done with the intention of saving the five and is known to have the effect of killing the one (See Foot, Philippa, “The Problem of Abortion and the Doctrine of Double Effect,” Oxford Review 5 (1967), pp. 5–15 Google Scholar). It would take a separate discussion to determine whether one has some culpability (reduced or otherwise) or no culpability at all for the merely possible effects of one's actions. That is a matter of the ethics of risking harm, rather than the ethics of causing harm as a side effect, a means, or an end. The implication of any individual and most groups in the harms of climate change is a matter of low—sometimes extremely low—probabilities, and for that reason I take it to be outside the scope of the DDE.

⁷ On the distinction between macro-level and micro-level harms, which is useful in attempting to link specific agents to specific harms, see Lawford-Smith, Holly, “Difference-Making and Individuals’ Climate-Related Obligations,” in Hayward, Clare and Roser, Dominic, eds., Climate Justice in a Non-Ideal World (New York: Oxford University Press, 2016), pp. 64–82 CrossRefGoogle Scholar.