¹ We do not aim to defend the legal contours of Civilian Immunity in this article. Famously, international law does not distinguish between combatants who are fighting for a just cause, and combatants who are fighting for an unjust cause. Our concern in this article is only with just combatants, and the constraints that they are under when fighting for a just cause. We set aside the legal and moral status of combatants fighting for an unjust cause.

² According to the ethics of killing in war, it is relatively uncontroversial that Immunity applies to at least those civilians who do not share in the moral responsibility for an unjust war that their country is fighting. It is contested whether Immunity applies to other civilians as well (for an argument against, see McMahan, Jeff, ‘The Ethics of Killing in War’, Ethics 114 (2004), pp. 693–733, at 725–9CrossRefGoogle Scholar; for an argument in favour, see Shue, Henry, ‘Do We Need a “Morality of War”?’, Just and Unjust Warriors, ed. Rodin, David and Shue, Henry (Oxford, 2008), pp. 87–111Google Scholar). It is not the purpose of our article to delimit precisely which civilians – or which individuals more generally – are morally protected by Immunity. We instead aim to investigate how Immunity can be justified in non-controversial cases, i.e. in cases where the physical integrity of non-threatening, non-responsible individuals is at stake. For ease of presentation, we label this set of individuals ‘civilians’. See also n. 4.

³ Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts, 8 June 1977 (AP I), articles 48 and 51(2).

⁴ The prohibition on targeting civilians as laid out in AP I is not absolute. According to article 51(3) of AP I, civilians who are ‘directly participating in hostilities’ lose their right not to be targeted. See also n. 2.

⁵ AP I, article 51(5).

⁶ AP I, article 57(2.a.ii–iii).

⁷ In the philosophical literature, Jonathan Bennett is one of the first to mention such a set of cases. See Bennett, Jonathan, Morality and Consequences: The Tanner Lectures on Human Values (Cambridge, 1980), p. 95Google Scholar.

⁸ For relevant exceptions to this rule, see Brandt, Richard, ‘Utilitarianism and the Rules of War’, Philosophy & Public Affairs 1 (2, 1971), pp. 145–65Google Scholar, and Shaw, William H., Utilitarianism and the Ethics of War (London and New York, 2016)CrossRefGoogle Scholar. Brandt's key claim is that from a utilitarian point of view, we have reason to implement necessity and proportionality constraints on the pursuit of military objectives. We discuss Shaw's views in section IV below.

⁹ See Bennett, Jonathan, The Act Itself (Oxford, 1998), ch. 11CrossRefGoogle Scholar.

¹⁰ Bennett, Morality and Consequences, p. 111.

¹¹ A standard reply to Bennett's objection contends that an agent intends harm if the harm is sufficiently close to the agent's goal, or to a necessary means to the agent's goal. For an early such argument, see Foot, Philippa, ‘The Problem of Abortion and the Doctrine of the Double Effect’, in Virtues and Vices (Berkeley, 1978), pp. 19–32, at 21–2Google Scholar. For more recent arguments, see e.g. FitzPatrick, William, ‘The Intend/Foresee Distinction and the Problem of “Closeness” ’, Philosophical Studies 128 (2006), pp. 585–617Google Scholar; Wedgwood, Ralph, ‘Defending Double Effect’, Ratio (new series) 24 (2011), pp. 384–401CrossRefGoogle Scholar; Hills, Alison, ‘Intentions, Foreseen Consequences and the Doctrine of Double Effect’, Philosophical Studies 133 (2007), pp. 257–83CrossRefGoogle Scholar. These approaches face many difficulties, see e.g. See Nelkin, Dana K. and Rickless, Samuel C., ‘So Close, Yet So Far: Why Solutions to the Closeness Problem for the Doctrine of Double Effect Fall Short’, Noûs 49 (2015), pp. 376–409CrossRefGoogle Scholar. Compare Tadros, Victor, ‘Wrongful Intentions Without Closeness’, Philosophy & Public Affairs 43 (2015), pp. 52–74, at 59–60CrossRefGoogle Scholar.

¹² Such a proposal was first articulated by Quinn, Warren in his ‘Actions, Intentions, and Consequences: The Doctrine of Double Effect’, Philosophy and Public Affairs 18 (1989), pp. 334–51Google ScholarPubMed. Versions of Quinn's proposal have recently been defended by Tadros, ‘Wrongful Intentions’, and by Nelkin, Dana K. and Rickless, Samuel C., ‘Three Cheers for Double Effect’, Philosophy and Phenomenological Research 89 (2014), pp. 125–58CrossRefGoogle Scholar.

¹³ See e.g. FitzPatrick, ‘The Intend/Foresee Distinction’; Cavanaugh, Thomas A., Double-Effect Reasoning: Doing Good and Avoiding Evil (Oxford, 2006), pp. 59–66CrossRefGoogle Scholar; Kamm, Frances, Intricate Ethics: Rights, Responsibilities, and Permissible Harm (Oxford, 2007), pp. 82–9CrossRefGoogle Scholar. For a reply, see Nelkin and Rickless, ‘Three Cheers’.

¹⁴ Thomson, Judith, ‘Self-Defense’, Philosophy & Public Affairs 20 (1991), pp. 283–310, at 290Google Scholar.

¹⁵ We assume that welfare is interpersonally comparable and measurable on a cardinal scale. This makes it reasonable to assume that under ideal uncertainty, agents who endorse a welfarist moral theory should aim at maximizing expected value (see sec. III.2 and, in particular, note 17).

¹⁶ This terminology will be introduced in more detail in section IV below.

¹⁷ This principle is one of a range of reasonable principles to guide welfarist deliberation under ideal uncertainty. More specifically, we concede that agents needn't be risk-neutral, but may reasonably be at least moderately risk-averse. The results that we discuss obtain whether agents are risk-neutral or risk-averse, and hence we do not discuss admissible risk aversion in the main text. Note that depending on how the cardinalization of welfare values is obtained, attitudes towards risk might already be embedded in the numbers that describe the values of outcomes.

¹⁸ For simplicity, we here assume that ‘being demoralized’ is a binary notion.

¹⁹ Kamm, Intricate Ethics, p. 141.

²⁰ See e.g. Kahneman, Daniel, Thinking: Fast and Slow (London, 2012)Google Scholar; Kahneman, Daniel and Lovallo, Dan, ‘Timid Choices and Bold Forecasts: A Cognitive Perspective on Risk Taking’, Management Science 39 (1993), pp. 17–31, esp. at 25CrossRefGoogle Scholar; Bertrand, Marianne, Chugh, Dolly, and Mullainathan, Sendhil, ‘Implicit Discrimination’, AEA Papers and Proceedings 95.2 (2005), pp. 94–8, esp. at 96Google Scholar.

²¹ Gigerenzer, Gerd and Goldstein, Daniel G., ‘Reasoning the Fast and Frugal Way: Models of Bounded Rationality’, Psychological Review 103 (1996), pp. 650–69CrossRefGoogle ScholarPubMed.

²² Shaw, Utilitarianism and the Ethics of War, pp. 120–40. See also Shaw, William H., ‘Utilitarianism and the Ethics of War’, The Cambridge Guide to Utilitarianism, ed. Eggleston, Ben and Miller, Dale E. (Cambridge, 2014), pp. 303–24, esp. at 321–3CrossRefGoogle Scholar.

²³ Shaw, Utilitarianism and the Ethics of War, pp. 130–1.

²⁴ Shaw, Utilitarianism and the Ethics of War, pp. 130–1.

²⁵ Kahneman and Lovallo, ‘Timid Choices and Bold Forecasts’, p. 27. See also Moore, Don A. and Healy, Paul J., ‘The Trouble with Overconfidence’, Psychological Review 115 (2008), pp. 502–17CrossRefGoogle ScholarPubMed. Moore and Healy refer to the specific phenomenon that we are interested in as ‘overestimation’.

²⁶ Montibeller, Gilberto and von Winterfeldt, Detlof, ‘Cognitive and Motivational Biases in Decision and Risk Analysis’, Risk Analysis 35 (2015), pp. 1230–51, at 1232CrossRefGoogle ScholarPubMed.

²⁷ Montibeller and von Winterfeldt, ‘Cognitive and Motivational Biases’, p. 1232. See also Kahneman and Lovallo, ‘Timid Choices and Bold Forecasts’.

²⁸ Johnson, Dominic D. P., Overconfidence and War: The Havoc and Glory of Positive Illusions (Cambridge, 2004)CrossRefGoogle Scholar.

²⁹ We use the term ‘ordinary’ to refer to less than fully rational agents who are prone to biases under normal uncertainty.

³⁰ We thank an anonymous referee for pointing out this fact.

³¹ See e.g. Haque, Adil Ahmad, Law and Morality at War (Oxford, 2017), p. 10CrossRefGoogle Scholar.

³² Cf. Shaw, Utilitarianism and the Ethics of War, pp. 138–9.

³³ We thank an anonymous reviewer for suggesting an argument along these lines.

³⁴ Cf. Morton, Jennifer M., ‘Toward an Ecological Theory of the Norms of Practical Deliberation’, European Journal of Philosophy, 19 (2010), pp. 561–84, esp. at 580CrossRefGoogle Scholar.

³⁵ Ferrero, Luca, ‘Decisions, Diachronic Autonomy and the Division of Deliberative Labor’, Philosopher's Imprint 10 (2010), pp. 1–23, at 7Google Scholar.

³⁶ <http://scienceblogs.com/cortex/2008/09/30/loss-aversion-and-the-stock-ma/>.

³⁷ See Horty, John, ‘Reasons as Defaults’, Philosophers Imprint 7 (2007), pp. 1–28Google Scholar. See also Walzer, Michael, Just and Unjust Wars, 3rd edn. (New York, 2000), pp. 231–2Google Scholar, where Walzer introduces the notion of a ‘supreme emergency’ during which the laws of war are suspended.

³⁸ The notion of pre-emption is seminally developed in Raz, Joseph, Practical Reasons and Norms (Princeton, 1990)Google Scholar, and Raz, Joseph, The Morality of Freedom (Oxford and New York, 1986)Google Scholar.

³⁹ See Morton, ‘Toward an Ecological Theory of the Norms of Practical Deliberation’, p. 578.

⁴⁰ There are a fair number of empirical studies that investigate the question of whether targeting civilians has helped further military objectives when civilians have been targeted in the past. If targeting civilians has frequently been ineffective, then this lends support to the idea that in cases where Immunity acts as an inhibitor, it frequently blocks largely ineffective harm whose infliction would not be justified from a welfarist perspective. There is, however, no agreement in the empirical literature on this issue. Influential studies arguing for the ineffectiveness of targeting civilians include Pape, Robert, Bombing to Win: Air Power and Coercion in War (London, 1996)Google Scholar and Abrahms, Max, ‘Why Terrorism Does Not Work’, International Security 31 (2006), pp. 42–78CrossRefGoogle Scholar. Influential studies arguing that targeting civilians has sometimes proved effective include Downes, Alexander, Targeting Civilians in War (Ithaca and London, 2008)Google Scholar and Lyall, Jason, ‘Does Indiscriminate Violence Incite Insurgent Attacks? Evidence from Chechnya’, Journal of Conflict Resolution 53 (2009), pp. 331–62CrossRefGoogle Scholar. For a careful review of the relevant literature and the methodological issues that empirical studies on the effectiveness of targeting civilians face, see Lazar, Seth, ‘Necessity and Non-combatant Immunity’, Review of International Studies 40 (2014), pp. 53–76CrossRefGoogle Scholar.

⁴¹ See e.g. Greene, Joshua D., ‘The Secret Joke of Kant's Soul’, Moral Psychology, ed. Sinnott-Armstrong, W., vol. 3 (Cambridge, 2008), pp. 35–79Google Scholar.

⁴² See Parfit, Derek, On What Matters: Volume I (Oxford, 2011)Google Scholar.

⁴³ Montibeller and von Winterfeldt, ‘Cognitive and Motivational Biases’, p. 1232.

⁴⁴ Montibeller and von Winterfeldt, ‘Cognitive and Motivational Biases’, p. 1232. See also Johnson, Overconfidence and War.

⁴⁵ For helpful discussions and comments on earlier versions of this article, we thank Tantum Collins, Matt Hitchens, Ariel Porat, Ofer Malcai, Andreas Schmidt, Arthur Ripstein, Eduardo Rivera-López, Bastian Steuwer, Alex Voorhoeve, audiences at an LSE Choice Group talk in March 2017, at the conference ‘Contemporary Just War Theory’ at Universidad Torcuato Di Tella' School of Law, and at the 7th Annual Conference of the Oxford Institute for Ethics, Law and Armed Conflict in September 2016, as well as two anonymous reviewers of this journal. Benbaji's research was supported by the Israel Science Foundation, grant number 304/15.