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Culpable Bystanders, Innocent Threats and the Ethics of Self-Defense1

Published online by Cambridge University Press:  01 January 2020

Yitzhak Benbaji
Bar-Ilan University, Ramat-Gan 52900, and Shalom Hartman Institute, Jerusalem, 93113, Israel


The moral right to act in self-defense seems to be unproblematic: you are allowed to kill an aggressor if doing so is necessary for saving your own life. Indeed, it seems that from the moral Standpoint, acting in self-defense is doing the right thing. Thanks, however, to works by George Fletcher and Judith Thomson, it is now well known how unstable the moral basis of the right to self-defense is. We are in the dark with regard to one of the most basic problems raised by this right, namely: the problem of the innocent aggressor. The disturbing question is simple enough: Is a potential victim allowed to kill, in self-defense, a morally innocent aggressor?

Research Article
Copyright © The Authors 2005

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2 Fletcher, G.Proportionality and the Psychotic Aggressor,’ Israel Law Review 8 (1973) 367-90CrossRefGoogle Scholar

3 Thomson, J.Self-Defense,’ Philosophy and Public Affairs 20 (1991) 283310;Google Scholar cf. also a much earlier paper, in which Thomson extensively uses the notion of Self-Defense: 'A Defense of Abortion,’ Philosophy and Public Affairs 20 (1971) 41-66

4 See Thomson, ‘Self-Defense,’ 289.

5 Ibid., 287-9

6 Ibid., 289 ff.

7 Ibid., 306

8 Robinson, P.A Theory of Justification,UCLA Law Review 23 (1975) 266-92,Google Scholar at 278, n. 49; quoted in Christopher, R.Self-Defense and Defense of Others,’ Philosophy & Public Affairs 27 (1998), 138.CrossRefGoogle Scholar Note, however, that the claim attributed here to Thomson is not as general as Robinson's claim. Thomson's theorem regards justified killing in self-defense, while Robinson makes a general Statement about justification. As a referee for the Canadian Journal of Philosophy correctly pointed out to me, many justifications are essentially agent relative. Suppose X is an official executioner for the government, and Y has been duly sentenced to death. X is justified in killing Y, but no one else is. Or, to take another example, you are justified in punishing your son, but no one else is. Two points should be stressed here: as far as I can see there cannot be essentially agent-relative justification for killing in self-defense. Secondly, even an agent-relative justification is sharable in some sense. With respect to the second example: I am prima facie justified in helping you to punish your son.

9 McMahan, J.Self-Defense and the Problem of the Innocent Attacker,’ Ethics 104 1994) 252-90,CrossRefGoogle Scholar at 278. McMahan's reason for this strong claim is that Thomson rejects the classical notion of rights exemplified by Raz's definition (Raz, Joseph The Morality of Freedom [Oxford: Clarendon Press 1986], 186Google Scholar). In Raz's view, one holds a right if an interest of his constitutes a sufficient reason for holding some other person under a duty.

10 Thomson, ‘Self-Defense,’ 285. One element in this argument will be rejected in the final section, namely: I shall agree that victim is not merely excused, but this does not imply that the victim is justified.

11 Ibid., 289

12 Zohar, N.Collective War and Individualistic Ethics: Against the Conscription of “Self-Defense,’Political Theory 21 (1993) 606-22,CrossRefGoogle Scholar at 608-9. Cf. Otsuka, M.Killing the Innocent in Self-Defense,’ Philosophy and Public Affairs 23 (1994) 7494.CrossRefGoogle Scholar

13 Zohar, ‘Collective War and Individualistic Ethics,’ 611-13

14 Zohar further Claims that our moral judgment determines the causal relation rather than flows from it. See Zohar, N.Innocent and Complex Threats: Upholding the War Ethic and the Condemnation of Terrorism,’ Ethics 114 (2004) 734-51.CrossRefGoogle Scholar

15 See Otuska, M.Killing the Innocent in Self-Defense,’ Philosophy and Public Affairs 23 (1994) 7494,CrossRefGoogle Scholar at 79. Compare Russell Christopher's analysis of such cases under Robinson's theory of justification in his ‘Unknowing Justification and the Logical Necessity of the Dadson Principle in Self-Defense,’ Oxford Journal of Legal Studies 15 (1995) 229-51, at 239-45.

16 Recall that for Thomson, having a right to kill in self-defense is equivalent to being justified in killing in self-defense. In an earlier article, however, Thomson insists that 'it cannot be concluded that you too can do nothing, that you cannot attack [the child] to save your life’ (Thomson, ‘A Defense of Abortion,’ 52). Nancy Ann Davis has argued that against an innocent threat the victim has merely a permission, not a right, to kill in self-defense. The difference is precisely that this does not transfer to third parties. See her ‘Abortion and Self-Defense,’ Philosophy and Public Affairs 14 (1984) 175-207.

17 As a referee for the Canadian Journal of Philosophy pointed out to me, Obligation* is clearly false.

Obligation*:if Z is X's physician, Z ought (all things considered) to take advantage of every right (permission) Z has, if this is necessary to save X's life in a 'medical’ Situation.

In a certain Situation, a physician may be permitted to sacrifice his own life to render medical care for his patient.

18 Hereafter, I shall omit the modifier ‘all-things-considered.’ But when I say that ‘X is justified’ I mean that X is all-things-considered justified.

19 Thomson, ‘Self-Defense,’ 289

20 Consider two types of robbers, the bloody-minded and the greedy. If you don't kill the bloody-minded robber, he will kill you unless you let him have your purse. The greedy robber, in contrast, won't kill you. He has no need to take such extreme measures: he is so much stronger than you that he would win a nonlethal struggle and have your money anyway. Shooting at him is the only way to stop him. Should there be a difference between the bloody-minded robber and the greedy one? Some might believe that it is forbidden to kill in self-defense, if you can save your life by letting the aggressor have (some of) your money. I, among many others, believe that, in the first case, but not in the second, you are allowed to fight back. There are other cases that support this intuition. If a minor attacks you, and you can survive without killing him, at the price of loosing a million dollars (you have to throw away a suitcase full of money in order to run fast enough), you must do it. The same is true of a psychotic (innocent) aggressor who attacks you and you can run away. But if a villain attacks you, you need not run away if enough money is at stake. If you didn't flee, you are allowed to kill him in order to save your life. Finally, suppose that you see a very good runner attacked by a psychotic aggressor. The would-be victim prefers not to run away. So he fights back and loses; now his life is in danger. Are you, the observer, allowed to defend him by killing the aggressor? I am not sure at all that a person who could have run and didn't should be saved by killing the aggressor, if the aggressor is innocent.

21 Zohar, ‘Collective War and Individualistic Ethics,’ 610

22 Ibid., 611

23 McMahan, ‘Self-Defense and the Problem of the Innocent Attacker,’ 260

24 Thanks for Jeff McMahan for this clarification of his position.

25 McMahan tends to bite the bullet. See J. McMahan, ‘Self-Defense and Culpability,’ forthcoming in Law and Philosophy; and ‘The Basis of Moral Liability to Defensive Killing’ Philosophical Issues 15 (2005) 386-405.

26 There are other Solutions that seem to me unattractive. According to one of them, self-defense is morally justified, because the aggressor is culpable and his culpable aggression is causally relevant to the inevitable harm to be shifted to him. According to this solution, a mere causal relation makes killing the innocent aggressor in self-defense more justified, but unless it is accompanied by culpability, this is an insufficient justification for shifting harm. Proponents of Justice tend to reject this explanation. They tend to believe that there is no morally relevant difference between an innocent threat and an innocent bystander. Alternatively, it might be claimed that mere causal relation — the fact that one is part of a threat which is to cause an inevitable harm — has no moral significance unless one culpably constitutes a threat. But this has to be explained. And the only explanation I see is presented in the text.

27 I borrowed this example from the Pogge/Cohen debate about Cohen's incentive objection to Rawls's theory of justice. See Pogge, T.On the Site of Distributive Justice: Reflections on Cohen and Murphy,Philosophy and Public Affairs 29 (2000) 136-69,CrossRefGoogle Scholar at 162. Cf. Cohen, G.A.Where the Action Is: On the Site of Distributive Justice,Philosophy and Public Affairs 26 (1997) 127.CrossRefGoogle Scholar

28 Y's liability won't do, for, in the case under discussion, in killing Y, X does not shift an inevitable harm to Y, because by killing Y, X does not avoid any harm.

29 McMahan, Jeff The Ethics of Killing (Oxford: Oxford University Press 2002), 237CrossRefGoogle Scholar

30 Ibid., 235

31 Ibid., 241

32 Ibid., 246.

33 Ibid., 242

34 Raz, The Morality of Freedom, 188.Google Scholar The conception of rights as ‘trumps’ is Dworkin's. See his ‘Taking Rights seriously,’ in Taking Rights Seriously (Cambridge, MA: Harvard University Press 1977).

35 Raz, The Morality of Freedom, 166

36 Ibid., 187

37 Ibid., 190

38 Some philosophers would bite this bullet — they would claim that morally speaking, attempts are as wrong as murders — this is, however, counterintuitive.

39 Raz, The Morality of Freedom, 179Google Scholar

40 I thank Noam Zohar for this Suggestion.

41 I develop this line of argument in my ‘A Defense of the ‘Traditional’ War-Convention.'

42 See Waldron, JeremeyA Right to Do Wrong,’ in Liberal Rights (Cambridge: Cambridge University Press 1993),Google Scholar esp. 66, 77; cf. Galston, W.G.On the Alleged Right to Do Wrong: A Response to Waldron,’ Ethics 93 (1983), 320-4;CrossRefGoogle Scholar Waldron, Galston on Rights,’ Ethics 93 (1983), 325-7;CrossRefGoogle Scholar and Enoch, D.A Right to Violate One's Duty,’ Law and Philosophy 21 (2002), 361.Google Scholar Cf. Thomson, Judith The Realm of Rights (Cambridge, MA: Harvard University Press 1990), 48.Google Scholar

43 See Nozick, R. Anarchy, State and Utopia (New York: Harper and Row 1974), ix.Google Scholar

44 See Thomson, In Defense of Abortion,63,Google Scholar where she discusses the Minimally Decent Samaritan.

45 The terminology I use is not Thomson's. She says it would be indecent not to allow one's body to be used for rescue, not that it would be wrong. She seems to believe that decent people are worthy of praise if they waive their rights. This appears to be quite close to the notion of supererogation.

46 The example is borrowed from Williams, B.A Critique of Utilitarianism,’ in Utilitarianism; For and Against, Smart, J.J. and Williams, B. eds. (Cambridge: Cambridge University Press 1973).Google Scholar

47 Williams himself never explicitly said that Jim has a right not to kill anyone and thereby let Pedro kill twenty.

48 See Raz, The Morality of Freedom, 188; Frankfurt, HarryEquality and Respect,’ reprinted in his Necessity, Volition, and Love (Cambridge: Cambridge University Press 1999), 152-4.Google Scholar

49 Thomson would probably say that I have made my impartial spectator too utilitarian. In her version, the impartial spectator would prefer the death of the falling man to the death of the victim. I shall claim, shortly, that my account of justification and impartiality yields better results.

50 See Wiggins, David Truth, Invention and the Meaning of Life (Oxford: Oxford University Press, 1976), 376;Google Scholar Sinnott-Armstrong, W.“Ought to Have” and “Could Have,’Analysis 45 (1985), 323-4;CrossRefGoogle Scholar cf. Marcus, R. BarcanMoral Dilemmas and Consistencies,’ Journal of Philosophy 77 (1980), 125.CrossRefGoogle Scholar Thomson, seems to disbelieve in moral dilemmas. See her ‘The Right and the Good,’ Journal of Philosophy 94 (1997), 284-6.CrossRefGoogle Scholar Some philosophers, most notably Daniel Statman, deny the very possibility of such dilemmas. See his Moral Dilemmas. (Atlanta, GA: Rodopi 1995)

51 McMahan, JeffSelf-Defense and the Problem of the Innocent Attacker,’ Ethics 104 (1994), 176CrossRefGoogle Scholar

52 It would be a mistake to conclude that killing an innocent threat in self-defense is always morally unjustified: if one person innocently threatens ten others, an impartial weighing would recommend preferring the ten; this would be harmful but not disrespectful to the one. The centrality of the realm of rights can be shown through a case in which the ten innocently threaten the one, and the one is able to kill the ten in self-defense. Killing the one in defense of the ten in this case is much more problematic.

53 I do not fully agree, because if one person innocently threatens ten people a third-party intervention is desirable. The reason for this is obvious in light of the discussion in the previous paragraph.

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