¹ See Nozick, Robert, Anarchy, State, and Utopia (New York, 1974)Google Scholar.

² See Rawls, John, A Theory of Justice (Cambridge, Mass., 1971), pp. 75–83Google Scholar.

³ Nozick, Anarchy, State, and Utopia, pp. 230–1.

⁴ See Rawls, John, A Theory of Justice, Revised Edition (Cambridge, Mass., 1999), p. 216Google Scholar.

⁵ See Kamm, Frances Myrna, Morality, Mortality, vol. 2: Rights, Duties, and Status (New York, 1996), pp. 121–2Google Scholar.

⁶ Henceforth, the ‘ideal-theory’ qualification will be implicit in references to libertarianism or a libertarian regime.

⁷ Locke's characterization of the state of nature as a pre-political situation in which ‘no one ought to harm another in his life, health, liberty, or possessions’ is in The Second Treatise of Civil Government (1690), ch. II.

⁸ Hayek takes great pains to defend the common law on the grounds that it enforces widely accepted ‘rules of just conduct’; Law, Legislation, and Liberty, vol. 1: Rules and Order (Chicago, 1973), pp. 94–123. He also observes that such rules ‘are negative in the sense that they normally impose no positive duties on any one, unless he has incurred such duties by his own actions’ (Law, Legislation, and Liberty, vol. 2: The Mirage of Social Justice (Chicago, 1976), p. 36). Other examples of libertarian theories that proclaim the supremacy of negative moral duties, although quite different in other respects from Nozick's and Hayek's, are Lomasky, Loren, Persons, Rights, and the Moral Community (New York, 1987), pp. 94–100Google Scholar; Narveson, Jan, The Libertarian Idea (Philadelphia, 1988), pp. 22–31 and 57–61Google Scholar; and Spector, Horacio, Autonomy and Rights (Oxford, 1992), pp. 101–51Google Scholar.

⁹ Otsuka, Michael, Libertarianism without Inequality (Oxford, 2003), pp. 3–4CrossRefGoogle Scholar. See also nn. 10 and 15. Both right and left libertarians uphold free markets, but differ on how people originally acquire property titles to external things. While right libertarians view external things as initially unowned and thus up for grabs, left libertarians view them as belonging to everyone in some egalitarian sense and thus allow private appropriation only if due compensation is paid to the other members of society. See Peter Vallentyne, ‘Libertarianism’, The Stanford Encyclopedia of Philosophy (Fall 2004 Edition), ed. Edward N. Zalta, URL = <http://plato.stanford.edu/archives/fall2004/entries/libertarianism/>.

¹⁰ Otsuka argues that libertarians committed to full self-ownership rights must confront the fact that ‘some incursions upon one's body (without one's consent) that result in serious harm’ seem permissible (Libertarianism without Inequality, p. 13). Otsuka believes that any plausible version of libertarianism must jettison a ‘full’ right of self-ownership. He consequently endorses a formulation of the self-ownership principle that permits the harmful incursions upon one's body condoned by the doctrine of the double effect (pp. 15, 69–70 and 76–8). I will criticize this doctrine in sect. IV. In any event, I do not see how relaxing the conditions under which killing is permissible may help libertarians resist the less dramatic redistributive measures that I will discuss in sects. III and IV.

¹¹ See Feinberg, Joel, The Moral Limits of the Criminal Law, vol. 1: Harm to Others (New York, 1984), p. 12Google Scholar, and Feinberg, Joel, The Moral Limits of the Criminal Law, vol. 2: Offense to Others (New York, 1988), pp. 3–38CrossRefGoogle Scholar.

¹² Thomson, Judith Jarvis, ‘Killing, Letting Die, and The Trolley Problem’, Ethics: Problems and Principles, ed. Fischer, John Martin and Ravizza, Mark (Forth Worth, 1992), p. 70Google Scholar, reprinted from The Monist 59 (1976), pp. 204–17. Imaginary cases are quoted from the cited works unless otherwise indicated.

¹³ Thomson, Judith Jarvis, The Realm of Rights (Cambridge, Mass., 1990), p. 176Google Scholar. Philippa Foot had presented a variant of this case in ‘The Problem of Abortion and the Doctrine of the Effect’, Double, Virtues and Vices and Other Essays in Moral Philosophy, ed. Foot, Philippa (Oxford, 1978), p. 23Google Scholar.

¹⁴ Thomson's original statement of the Trolley Problem is in ‘The Trolley Problem’, The Yale Law Journal 94 (1985), pp. 1395–6. See also her formulation of the problem in The Realm of Rights, pp. 177–8.

¹⁵ See Otsuka, Michael, ‘Self-Ownership and Equality: A Lockean Reconciliation’, Philosophy and Public Affairs 27 (1998), p. 69CrossRefGoogle Scholar. Otsuka's remark does not apply, however, to libertarians who do not endorse the mirroring view. To the best of my knowledge, Spector, Autonomy and Rights, ch. 4, is the first defence of libertarianism that employs a discussion of imaginary cases where the agent faces a choice between killing and letting die. See sect. V for a discussion of the mirroring view.

¹⁶ The Realm of Rights, pp. 181–7.

¹⁷ The Realm of Rights, p. 184.

¹⁸ The Realm of Rights, p. 188.

¹⁹ The case's title is mine.

²⁰ The Realm of Rights, p. 187.

²¹ The Realm of Rights, p. 188.

²² The Realm of Rights, pp. 187–9.

²³ In The Realm of Rights, p. 189, Thomson points out that she understands the notion of ‘good for a person’, which she uses interchangeably with that of ‘advantageous for a person’, as an objective notion, i.e. independent of the person's preferences or desires.

²⁴ Can the difference between the Christian-Scientist and the putative-Cock-Robin cases be explained by distinguishing between hypothetical consent and lack of (genuine) consent, respectively? Not in the context of Thomson's account, which uses a notion of ‘consent’ that is thin enough to allow her to describe the putative Cock Robin as someone who ‘would consent to your slitting his throat’ (emphasis mine). But even if we distinguished the two cases as displaying different types of consent (e.g. genuine vs. vitiated consent), or as involving consent and the absence thereof, my circularity objection would persist, for we could not draw the requisite distinction without criteria about the permissibility of deferring to a person's views (whether they are indicative of genuine consent or not).

²⁵ Kamm, Frances Myrna, ‘Harming Some to Save Others’, Philosophical Studies 57 (1989), pp. 227–60CrossRefGoogle Scholar.

²⁶ Morality, Mortality, vol. II, p. 201n. Kamm indicates that she had offered a ‘somewhat’ different formulation of the principle in ‘Harming Some to Save Others’.

²⁷ ‘Harming Some to Save Others’, p. 232. The PI/PH may be viewed, then, as a way of spelling out the doctrine of the double effect, which I briefly discuss at the end of this section.

²⁸ ‘Harming Some to Save Others’, p. 233.

²⁹ The name of the case is mine.

³⁰ Foot, ‘The Problem of Abortion and the Doctrine of the Double Effect’, p. 29. Text slightly altered.

³¹ Jeff McMahan makes this point in ‘Killing, Letting Die, and Withdrawing Aid’, Ethics 103 (1993), pp. 250–79, at p. 276n.

³² Eric Rakowski discusses this variant in ‘Taking and Saving Lives’, Columbia Law Review 93 (1993), pp. 1063–1156, at pp. 1088–9.

³³ Morality, Mortality, p. 174.

³⁴ Morality, Mortality, p. 151.

³⁵ Morality, Mortality, p. 174 (Kamm's emphasis).

³⁶ Alternatively, it may be, as she also says, an aspect of the act that saves the five. See sect. IV.

³⁷ Morality, Mortality, p. 174. The case's title is mine.

³⁸ Morality, Mortality, p. 174.

³⁹ Thomson points out that Transplant fails to fulfil (a) because ‘how one lives affects one's health’, and to that extent it differs from Trolley, in which the six are assumed to be randomly distributed between the two tracks. See The Realm of Rights, pp. 183–7.

⁴⁰ The Realm of Rights, pp. 185–6.

⁴¹ Since the causal view appeals to maximization of probabilities of survival, it arguably generates a duty to save the five in Trolley-like situations, rather than to its being merely permissible. On similar grounds, Eric Rakowski argues that Thomson's theory entails a duty to save the five (‘Taking and Saving Lives’, pp. 1103–4 and 1145–6). Thomson argues that the passer-by may, but is not morally required to, turn the trolley, and suggests that this follows from her rejection of utilitarianism. See The Realm of Rights, p. 196. A duty to save the five, rather than the mere permissibility of saving them, would be especially troublesome to libertarians committed to the mirroring view.

⁴² I will offer a slightly refined formulation of the causal view in sect. III, again with no intent to offer a full-fledged solution to the Trolley Problem.

⁴³ I am indebted to Horacio Spector for this example.

⁴⁴ Notice that this argument may fail to help the libertarian in some cases of ‘redirecting’ recessions or other social misfortunes. If, to minimize losses, government were to redirect a recession or a passer-by were to redirect a runaway trolley, the taxpayers or the lesser group on the tracks, respectively, would be deprived of something they would have had (their money or their lives) should the threat have followed its original course. On the other hand, such a ‘redistribution’ would leave both the potential unemployed and the five, respectively, unharmed. (I am grateful to Marcelo Ferrante for this point.) Perhaps libertarians can resist this analogy between the recession case and Trolley by requiring that threats be redirected in a non-metaphorical sense, that is, in a sense in which trolleys, but not recessions, can literally be redirected. Be that as it may, libertarians can resort to the ‘until redistribution’ baseline to oppose many usual redistributive policies that arguably benefit some non-threatened people.

⁴⁵ The ensuing discussion assumes what I take to be common-sense views about causal lengths.

⁴⁶ Kamm does not deal with applications of the PI/PH beyond choices between killing and letting die.

⁴⁷ This cannot be conclusive, though, since standard economics disallows interpersonal comparisons of utility.

⁴⁸ For an analysis of the ‘legal incidents’ or bundle of rights involved in the ‘full’ or ‘liberal’ conception of ownership, see Tony Honoré, ‘Ownership’, Oxford Essays in Jurisprudence, ed. G. A. Guest (Oxford, 1961), pp. 107–47.

⁴⁹ Morality, Mortality, p. 154.

⁵⁰ Morality, Mortality, p. 173.

⁵¹ Morality, Mortality, p. 173.

⁵² We might also say that the PPH forbids starting a continuous causal process from the one to the five. This would explain the moral difference between Healing Breath and the transfusion cases imagined in the text. Thanks to Fred D. Miller Jr. for suggesting me to compare Healing Breath with forcible-transfusion cases.

⁵³ I ignore actions that have both good and bad flip sides. The possibilities discussed in the text will sufficiently display, I think, the inadequacy of the libertarian strategy based on the mirroring view.

⁵⁴ I follow here Kamm, ‘Harming Some to Save Others’, p. 230. The wording of Prevented Return is mine, except the case's title, which belongs to Kamm. In ‘The Trolley Problem’, pp. 1401–3, Thomson discusses and rejects the criterion based on the idea of ‘needing’ or ‘treating as a means’, and presents a case similar to Prevented Return.

⁵⁵ For further difficulties in the doctrine of the double effect, see Spector's excellent discussion in Autonomy and Rights, pp. 101–13.

⁵⁶ See Schmidtz, David, The Elements of Justice (Cambridge, 2006)CrossRefGoogle Scholar. For a critique of utilitarian, deontological and virtue-based approaches to the Trolley Problem, premised on agents’ epistemic and motivational shortcomings, see Griffin, James, Value Judgement: Improving Our Ethical Beliefs (Oxford, 1996), pp. 98–122Google Scholar.

⁵⁷ For a defence of this method, see Heidi Malm, ‘In Defense of the Contrast Strategy’, Ethics: Problems and Principles, ed. Fischer and Ravizza, pp. 271–7.

⁵⁸ See examples in nn. 1, 5, 8 and 15.

⁵⁹ Merging moral with legal considerations (e.g. a moral duty to help the needy and a specific welfare programme, respectively) is indeed common in contemporary political philosophy. See Pincione, Guido and Tesón, Fernando R., ‘Rational Ignorance and Political Morality’, Philosophy and Phenomenological Research 72 (2006), pp. 71–96CrossRefGoogle Scholar.

⁶⁰ Rawls, A Theory of Justice, Revised Edition, pp. xv–xvi.

⁶¹ Rawls, A Theory of Justice, Revised Edition, p. xvi.

⁶² Rawls, John, Justice as Fairness: A Restatement (Cambridge, Mass., 2001), p. 137Google Scholar.

⁶³ For a critique of expressive models of counterproductive political discourse, see Pincione, Guido and Tesón, Fernando R., ‘Self-Defeating Symbolism in Politics’, The Journal of Philosophy 98 (2001), pp. 636–52CrossRefGoogle Scholar.

⁶⁴ I am indebted to the Social Philosophy and Policy Center, Bowling Green State University, where I was able to make substantial progress with this article. I also thank the Universidad Torcuato Di Tella Law School for its support. Finally, I am grateful to Geoffrey Brennan, Fred D. Miller Jr., Thomas Pogge, Eduardo Rivera López, Gonzalo Rodríguez Pereyra, David Schmidtz, Horacio Spector, Fernando R. Tesón and the Editor of Utilitas for their valuable comments on earlier drafts.