¹ McCarthy, David, ‘Harming and Allowing Harm’, Ethics 110 (2000), pp. 749–79CrossRefGoogle Scholar, at 749. There are also other interpretations of DDA. One interpretation is that doing harm makes an agent more reprehensible, which seems to be the interpretation assumed in Rachels, James, ‘Active and Passive Euthanasia’, New England Journal of Medicine 292 (1975), pp. 78–80CrossRefGoogle ScholarPubMed, especially in his discussion of the famous Smith–Jones case. Another interpretation is that doing harm constitutes a greater moral evil than allowing harm. This interpretation is assumed in Lichtenberg, Judith, ‘The Moral Equivalence of Action and Omission’, Canadian Journal of Philosophy 8 (1982), pp. 19–36CrossRefGoogle Scholar; and also in Nesbitt, Winston, ‘Is Killing No Worse than Letting Die’, Journal of Applied Philosophy 12 (1995), pp. 101–5CrossRefGoogle ScholarPubMed. The ‘Asymmetrical Constraints’ interpretation, as I will show, is actually equivalent to the ‘greater moral evil’ interpretation.

² For challenges to DDA, see Rachels, ‘Active’; Tooley, Michael, Abortion and Infanticide (Oxford, 1983)Google Scholar; and Lichtenberg, ‘Moral Equivalence’.

³ For a helpful survey of various defences of DDA and their problems, see Norcross's, Alastair introduction to Killing and Letting Die, 2nd edn., ed. Steinbock, B. and Norcross, A. (New York, 1994), pp. 1–23Google Scholar; and Frances Howard-Snyder, ‘Doing vs. Allowing Harm’, Stanford Encyclopedia of Philosophy, <http://plato.stanford.edu/entries/doing-allowing/> (2007).

⁴ The doctrine can also be defended in a less robust way: even if there is no sound conceptual distinction that matches our ordinary use of the concepts in a wide range of cases, the doctrine can still be defended by showing that there is at least a justification for the alleged moral difference between cases that are typically regarded as harm-doing and cases that are typically regarded as harm-allowing.

⁵ By ‘act’, I mean any intentional behaviour. I understand ‘act’ in a very loose sense here: an intentional non-performance can be called an act of allowing harm.

⁶ For proposals of the conceptual distinction, see Bennett, Jonathan, ‘Negation and Abstention: Two Theories of Allowing’, Ethics 104 (1993), pp. 75–96CrossRefGoogle Scholar; Foot, ‘Killing and Letting Die’, Killing and Letting Die, pp. 280–9; Donagan, Alan, The Theory of Morality (Chicago, 1977)Google Scholar; Warren S. Quinn, ‘Actions, Intentions, and Consequences: The Doctrine of Doing and Allowing’, Killing and Letting Die, pp. 355–82; and Jeff McMahan, ‘Killing, Letting Die and Withdrawing Aid’, Killing and Letting Die, pp. 383–420. For justifications of the alleged moral difference, see Foot, Philippa, ‘Euthanasia’, Philosophy and Public Affairs 6 (1977), pp. 85–112Google ScholarPubMed; Nesbitt, ‘Letting Die’; McCarthy, ‘Harming’; Scheffler, Samuel, ‘Doing and Allowing’, Ethics 114 (2004), pp. 215–39CrossRefGoogle Scholar; and Kamm, F. M., Intricate Ethics: Rights, Responsibilities, and Permissible Harm (Oxford, 2006)Google Scholar.

⁷ See, for example, Foot, ‘Euthanasia’, ‘Killing’; and Quinn, ‘Actions’.

⁸ Foot, ‘Killing’, p. 284.

⁹ Foot, , ‘Morality, Action and Outcome’, Morality and Objectivity: A Tribute to J. L. Mackie, ed. Honderich, T. (London, 1985), pp. 22–38Google Scholar, at 24.

¹⁰ Foot, ‘Killing’, p. 286.

¹¹ One example Foot uses is the wounded soldier case. See Foot, ‘Euthanasia’, p. 100.

¹² Norcross, Killing and Letting Die, p. 16.

¹³ Draper, Kai, ‘Rights and the Doctrine of Doing and Allowing’, Philosophy and Public Affairs 33 (2005), pp. 253–80CrossRefGoogle Scholar. Although Draper agrees that the rights-based theory provides an explanation of the alleged moral difference between cases that are typically regarded as harm-doing and cases that are typically regarded as harm-allowing, unlike Foot, Draper does not think the rights-based theory helps to establish a conceptual distinction between doing and allowing that matches our ordinary use of those concepts in a wider range of cases. So, Draper urges us to jettison DDA for a pure rights-based approach.

¹⁴ Draper, ‘Rights’, p. 277.

¹⁵ This point mirrors Fiona Woollard's criticism of F. M. Kamm's argument for constraints against harming based on inviolability, in which Woollard argues that it is not clear, according to Kamm's account, why ‘protection against being harmed is a better reflection of high moral worth than protection against being allowed to suffer avoidable harm’. Woollard, , ‘Intricate Ethics and Inviolability: Frances Kamm's Nonconsequentialism’, Ratio 21 (2008), pp. 231–8CrossRefGoogle Scholar, at 238.

¹⁶ When a person interferes with others’ autonomy with a positive justification, which overrides the moral need to protect autonomy, the interference is still unjust (though it is justified). For example, when you use my car for an urgent hospital visit without my permission, your act unjustly interferes with my autonomy (you wrong me) even if you may be justified in doing so. Here, I am following Jeff McMahan's distinction between ‘just’ and ‘justified’ in his Killing in War (Oxford, 2009).

¹⁷ Thanks to the reviewer of this journal for raising this objection. It helped to shape an important distinction, which, as we shall see, is needed to solve a troubling issue in the next objection.

¹⁸ One may say that there is indeed a distinct moral evil in the violation of positive rights, i.e. the agent's disregard to others’ well-being. However, bad characters or attitudes belong to agent evaluation, and my primary focus here is act evaluation. Furthermore, even if we take agent evaluation into consideration, we can still say that in a violation of negative rights, the agent manifests not only a disregard to others’ well-being, but also a disregard for others’ autonomy, in particular their protection against unjust interfering. Thus, we still have an asymmetry here.

¹⁹ Here I focus on the intrinsic moral value of the mere freedom itself. I leave aside all the contingent moral goods that may result from the enjoyment of such freedom, and I also leave aside all the well-being-related functions that may be required to enjoy such freedom (such as the physical capacity to hold a gun). The freedom to kill someone may bring me his money, but the well-being value of the money is certainly not intrinsic to the freedom itself. The capacity to hold a gun has some well-being value, but it does not mean that the mere freedom to shoot someone, which requires that capacity, has that well-being value itself. I think to view the mere freedom to shoot someone as a well-being, something that is entitled to respect, is to slap the idea of autonomy in the face.

²⁰ See, for example, Singer, Peter, ‘Famine, Affluence, and Morality’, Philosophy & Public Affairs 3 (1972), pp. 229–43Google Scholar.

²¹ There is no need to include further the loss of the victim's authority* over the agent in our assessment, since the moral significance of the loss of that authority*, as I have argued, is exhausted by the loss of the victim's well-being and her corresponding authority, which has already been included in the assessment.

²² Again, there is no need to know the comparative weight of the negative value and the positive value involved. All we need to know about the moral difference is that harm-allowing involves one less evil and one more good.

²³ See, for example, Scheffler, , ‘Prerogatives without Restrictions’, Philosophical Perspectives 6 (1992), pp. 377–97CrossRefGoogle Scholar; and Haydar, Bashshar, ‘Consequentialism and the Doing–Allowing Distinction’, Utilitas 14 (2002), pp. 96–107CrossRefGoogle Scholar.

²⁴ Haydar, ‘Consequentialism’, p. 103.

²⁵ For a discussion of these two conditions for moral responsibility, see, for example, Fischer, J. M. and Ravizza, M., Responsibility and Control: A Theory of Moral Responsibility (New York, 1998), p. 13CrossRefGoogle Scholar.

²⁶ I think ‘allowing a harmful sequence to complete’ is too strong a condition for allowing harm. Merely allowing a harmful sequence to continue should count as harm-allowing. Otherwise, cases in which the harm is allowed but fails eventually to occur owing to some other reasons would not count as harm-allowing, which seems incorrect.

²⁷ I think, in the simple cases, it is quite intuitive that, as Foot suggests, initiating a harmful sequence constitutes an unjust interfering with autonomy but merely allowing a harmful sequence to continue does not. One may object that my analysis is also incomplete because I simply appeal to our intuition to draw the conceptual distinction here. However, this appeal to intuition is quite different from the appeal to intuition that we saw in the rights-based analysis. It is problematic to explain an important moral distinction by simply appealing to some obscure intuitions. But it is much less problematic to explain a conceptual distinction by appealing to a seemingly unproblematic conceptual intuition. So, even if my conceptual analysis here is, in this sense, incomplete (as any analysis has to stop somewhere), I do not think my analysis of DDA as a whole involves any circularity or the kind of incompleteness that the rights-based analysis faces.

²⁸ This is a case originally discussed in McMahan, ‘Killing, Letting’. A few details are changed.

²⁹ McMahan, ‘Killing, Letting’, p. 389.

³⁰ McMahan, ‘Killing, Letting’, p. 396.

³¹ McMahan, ‘Killing, Letting’, p. 396.

³² McMahan, ‘Killing, Letting’, p. 396.

³³ According to McMahan, ‘[W]hen an agent withdraws aid or protection from a lethal threat that he has not himself provided, or when he withdraws aid or protection that he has provided but which was complete and self-sustaining, his action counts as killing; but when an agent withdraws aid or protection that he himself has provided but which requires further contributions from him to be effective, then his action counts as letting the victim die.’ Furthermore, ‘[I]f a person requires or is dependent for survival on further aid from or protection by an agent, and if the person dies because the agent fails to provide further aid or withdraws his own aid either while it is in progress or before it becomes operative, and if the agent is not causally responsible for the person's need for aid or protection, then the agent lets the person die.’

³⁴ Howard-Snyder, ‘Doing vs. Allowing’, sect. 8.

³⁵ Draper makes a similar point in his criticism to McMahan. See Draper, ‘Rights’, p. 266.

³⁶ I understand an obstacle that prevents a harmful sequence in a very broad sense. A car that happens to stand between a running trolley car and me is an obstacle to prevent the trolley car from harming me. A samaritan's effort to save a drowning child can also be regarded as an obstacle that prevents a harmful sequence, namely, the child's drowning.

³⁷ I am grateful to Peter Vallentyne, Peter Markie, Kai Draper, Robert Johnson, Crystal Allen, Daniel Marshall, Ashton Sperry and Wenwen Fan for constructive comments. I am especially indebted to an anonymous reviewer for this journal for insightful comments.