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JMP Discussion at PEA Soup: Kerah Gordon-Solmon’s “Self-Defence Against Multiple Threats” with a critical précis by Renee Jorgensen Bolinger

Welcome to the third Journal of Moral Philosophy discussion here at PEA Soup will take place on July 21-23. This is sure to be another insightful and productive discussion, this time on Kerah Gordon-Solmon “Self-Defence Against Multiple Threats.” This paper is currently available in the “Advance Articles” section online at the Journal of Moral Philosophy. They have kindly provided free access to the paper, which can be viewed or downloaded here. Renee Jorgensen Bolinger wrote a critical précis and commentary which is posted below. Please join the fun!

Renee Jorgensen Bolinger’s critical précis

Kerah Gordon-Solmon’s paper gives an impressively clear and concise statement of the problem of self-defense against multiple threats and offers a clever reply on behalf of the responsibility theorist. The central puzzle is how to restrict liability-based justifications for defense from permitting a defender to kill arbitrarily many minimally responsible threats in self-defense.

How the Problem Gets Going

To be liable to some harm H is to have forfeited your right against suffering H certain circumstances; in those circumstances, a defender who imposes H on you does not wrong you, and you lack counter-defensive rights. Kerah outlines three conditions which she treats as jointly sufficient individually necessary for liability:

  1. Instrumentality (also called a ‘success’ condition): the harm must achieve a justifying good (e.g. saving the victim’s life), or be an unavoidable side-effect of an act that does.
  2. Necessity: the harm-producing act must be necessary for bringing about this good.
  3. Narrow proportionality: the harm to the liable party must be proportionate to the good being brought about, given each party’s comparative responsibility. All else equal, if the defensive act would save a non-responsible victim’s life, then killing a responsible threat will be narrowly proportionate.

The fact that a threatener is liable to be killed gives the defender pro tanto justification for defensively killing her, but this justification can be defeated if the necessary defensive action would violate wide proportionality. A defensive action violates the wide proportionality constraint if the badness of the act (in terms of the harms it imposes on parties not liable to them) outweighs the good it achieves.

A Minimally Responsible Threat is someone who non-culpably exercises their agency in a way that foreseeably but improbably poses a threat to Victim. To illustrate, Kerah (following McMahan) offers the conscientious driver:

Conscientious Driver: A person who keeps her car well maintained and always drives cautiously and alertly decides to drive to the movies. … [F]reak circumstances cause the car to go out of control. It has veered in the direction of a pedestrian whom it will kill unless she blows it up [with an] explosive device.” (127)

Assume that other things are equal: there aren’t relevant variances in the two parties’ life expectancies, associated harms to third parties, etc. Since either Driver or Pedestrian must die, and this fact holds because of a risk that Driver took, it seems fair that Driver be the one to die. Using the explosive (and thus killing the driver) satisfies the three conditions, and so Driver is liable and Pedestrian is permitted to kill her in self-defense.

This seems to unavoidably commit the theorist to the troublesome verdict that is the focus of the paper. Suppose rather than being threatened by one driver, Pedestrian’s life is in fact threatened by many drivers, each minimally responsible but liable to be defensively killed, in precisely the same way as the conscientious driver case.

1,000 Drivers: A thousand people, each of whom keeps their car well maintained and always drives cautiously, decide to drive to run various errands. Freak circumstances cause all their cars to go out of control, veering in the direction of a single pedestrian. Each car is sufficient to kill the pedestrian, and unless stopped will kill the pedestrian at precisely the same moment. The pedestrian can save her life only by blowing up each of the 1,000 vehicles before impact; luckily, she is prepared and can do exactly that.

Intuitively, given the minimal responsibility of the threats, it is not morally permissible—because disproportionate—for the pedestrian to kill all thousand drivers to preserve her own life, regardless of whether doing so would impose harms on third parties.

The responsibility account doesn’t seem able to get this verdict. By stipulation, each killing is necessary for saving the pedestrian, and, so long as she in fact kills all the drivers, each is instrumental in saving her. As Kerah writes, “Each killing will save the pedestrian’s life. Because in each case the driver is minimally responsible and the pedestrian is non-responsible, each killing is narrowly proportionate.” (128) So, screening off complications (e.g. third parties), Pedestrian’s liability-based justification for defensively killing each of the thousand drivers will be defeated only if the badness of the harms to the drivers violates wide proportionality. But only harms to which the sufferers are not liable count against wide proportionality, and each driver is liable to be defensively killed, so their deaths don’t count against wide proportionality. Absent other harms to tally, the responsibility theorist seems committed to the conclusion that the liability justification is undefeated, and Pedestrian is morally permitted to kill all thousand.

The Solution: Side-Effect Harms

Kerah’s general strategy is to solve the puzzle by demonstrating that each killing also imposes a side-effect harm on each of the other drivers, to which they are not liable, which when taken together violate the wide proportionality constraint. In brief, “the pedestrian’s killing all the drivers also makes each of them substantially worse off as a side-effect, by bringing it about (1) that each is liable to be killed, and (2) that, consequently, she kills each.” (130)

The arguments for this conclusion proceeds roughly as follows. It’s a necessary condition on each driver’s liability that all the other drivers are killed. If they are not, then Pedestrian will still die, so the good achieved by killing a given driver is only protecting Pedestrian from this driver, which is not narrowly proportionate to the harm of killing the driver. So unless all the drivers will be killed (and thus Pedestrian saved), none of them is liable. Each killing thus has the side-effect of fulfilling one of the necessary conditions on each other driver’s liability to be defensively killed. The aggregate effects of killing the other 999 drivers therefore renders a given driver substantially worse off (because it makes her liable to be defensively killed) than she would otherwise be.

This obviously implies that in killing the drivers, Pedestrian harms each twice over: once in securing their liability, and once in killing them. So, counterintuitively, Pedestrian inflicts significantly more harm on each driver in the 1,000 drivers case than she does in the single driver case, despite performing the same action on each. Kerah embraces this implication, defending it by offering two ways in which each of the thousand drivers, but not the single driver, are made worse off by the pedestrian’s defensive killing.

  • In the 1,000 driver case, it is initially indeterminate whether each driver is liable to be defensively killed: it depends on whether the pedestrian will succeed in killing all 1,000. By contrast, the single driver starts out liable. So, in making the 1,000 drivers liable, the pedestrian worsens their position compared to where each started, but the same cannot be said of the single driver.
  • Non-comparatively, each killing deprives the 1,000 drivers of a good they previously enjoyed: it removes a shield each driver had enjoyed between her and liability, namely, the presence of the other threatening drivers. The single driver had no similar good, and so does not suffer similar deprivation.

For the imposition of these side-effect harms to render Pedestrian’s defensive killings widely disproportionate, the drivers cannot be liable to suffer these harms. As defined, to be liable to some harm requires having forfeited a right against suffering that harm. Kerah notes (plausibly enough) that it’s doubtful the drivers ever had a right against “having the liability justification on the basis of which she’s killed secured by the killing of other people” (132), and of course one cannot forfeit rights that one never had. So, at least on this definition of liability, it follows that the drivers are not liable to these side-effect harms.

Kerah contends that for minimally responsible threats, the aggregate impersonal badness of these harms outweighs the badness of the death of the pedestrian. Importantly, she holds that this impersonal badness decreases with increasing culpability, such that the harm to fully culpable threats is either not impersonally bad or below the threshold of additivity. If it holds, this argument should give the responsibility theorist the resources to secure the intuitive verdicts, allowing defenders to kill arbitrarily many culpable threats, but setting some limit to the number of minimally responsible threats that can be permissibly killed.

There’s a lot to say about the overall argument, but for brevity I’ll focus on just one concern.  It’s a little unclear whether we are supposed to understand the side-effect harms as consisting in (i) making the drivers more likely to be defensively killed, since the pedestrian is more confident that she is morally justified in defensively killing, or (ii)  directly making the drivers morally liable to such killing. The former makes sense of the epistemic language used at various points in the paper (especially p. 130), but doesn’t seem to address what was troubling about the puzzle. Whether the pedestrian is likely to kill all thousand drivers is a bit beside the point, really; the worry is that the theory says she is morally permitted to, and that seems false.

The latter would address the worry, but I’m not sure the arguments in the paper secure it. I’m concerned that (merely) epistemic uncertainty is doing a lot of the work in making the case for the existence of the side-effect harms. To screen that out, consider a variant of the thousand drivers case:

Simultaneous: Like the thousand drivers case, but Pedestrian has been armed with a button that will, either immediately or in a sequence that will definitely complete in time to save her life, vaporize all 1,000 cars and drivers.

The important difference between this and the original thousand drivers case is that in this variant, there’s no question about whether the Pedestrian will succeed in securing the justifying good (saving her own life).  It’s hard to see a case for considering it indeterminate whether each driver is liable here, and equally hard to construe the presence of the other drivers as a shield from liability. But then it doesn’t look like the argument from side-effect harms can get purchase: none of these drivers are made worse off by the other drivers’ deaths.

Intuitively, though, if liabilities are fact-relative (as they are on the Responsibility Account), the verdicts in 1,000 Drivers and Simultaneous should match. Holding fixed that she will in fact succeed in saving her life, it isn’t especially plausible that whether Pedestrian violates wide proportionality in defensively killing a thousand minimally responsible threats depends on whether she must kill them one by one or whether she has a button that will accomplish all the killings at once.

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14 Responses to JMP Discussion at PEA Soup: Kerah Gordon-Solmon’s “Self-Defence Against Multiple Threats” with a critical précis by Renee Jorgensen Bolinger

  1. Thanks to Renee for her précis. Here is my take on Kerah’s paper:
    Kerah thinks that McMahan’s account of liability and the justification of self-defense has embarrassing implications in the case of multiple conscientious drivers. McMahan’s account (setting his recent amendments in the volume The Ethics of War aside, which I find ad hoc) would imply that a large number of conscientious drivers may be killed to save just one pedestrian. That, says Kerah, is counter-intuitive. Her solution is to argue that killing any one of the conscientious drivers without also killing all the others would be “narrowly disproportionate” and hence a rights-violation and impermissible (without a lesser evil justification) since the pedestrian would still get killed, and to then further argue that “by killing all the drivers, the pedestrian would also cause a non-trivial side-effect harm to each one” (129), namely “by securing the liability justification on the basis of which she kills” them (130). This side-effect harm concerns “wide proportionality” and thus not liability (but still permissibility). Since Kerah finds the claim that the single conscientious driver can be permissibly killed but not the claim that 1000 conscientious drivers can, she then offers the following explanation for this distinction: “Since the thousand drivers start off in better-off positions than the single driver (of indeter¬minate liability; each with a greater chance of survival), by making the thousand drivers and the single driver equally badly off, the pedestrian worsens the position of each of the thousand drivers more than she worsens the single driver’s.” (131)
    But why is the single driver supposed to be liable, while the pedestrian is not? Because, Kerah says, “‘conscientious walking’ does not impose on any¬one a risk comparable to the risk imposed by driving.” (128) Actually, on the basis of her very own account it does. If the conscientious driver can foresee that he might collide with a pedestrian, a pedestrian can foresee that he might collide with a conscientious driver, and at least if the pedestrian accepts Kerah’s account (and Kerah seems to require that she does, see p. 130), she can foresee that thereby she imposes the risk on drivers of securing their liability by walking into their path– after all, if she weren’t there on the street to collide with the car, the driver would not become liable in the first place. So the pedestrian imposes on the driver the risk of securing his liability by being in his path; and on Kerah’s assumptions (130) the pedestrian will then proceed to kill the driver.
    Now there are different possibilities here. If the pedestrian (as Kerah claims) does not become liable in this situation, then this means that the risk the driver imposes on her is only the risk of killing (or injuring) her, but not the risk of making her liable. Yet, the pedestrian imposes both risks on the driver: the risk of securing the driver’s liability and the risk of killing him. (Kerah expressly accepts and in fact relies on this way of harming “twice over,” see pp. 130-131). Thus, the pedestrian actually imposes a greater risk on the driver than the driver imposes on the pedestrian. But then it should be the pedestrian (contrary to what Kerah claims, but her account implies) who is liable, not the driver. In others words: on Kerah’s account, if the driver is liable and the pedestrian is not, then the driver cannot be liable but the pedestrian is – a veritable contradiction. The other possibility is that one claims that the pedestrian also becomes liable. However, Kerah’s very definition of liability is not compatible with symmetrical liability, at least if she means by a right to defend oneself also a liberty-right, not only a claim-right (126). Thus, however you tweak and twist it, Kerah’s account seems to be incoherent.
    Let us go back to Kerah’s claim, already quoted: “Since the thousand drivers start off in better-off positions than the single driver (of indeter¬minate liability; each with a greater chance of survival), by making the thousand drivers and the single driver equally badly off, the pedestrian worsens the position of each of the thousand drivers more than she worsens the single driver’s.” In reply: there is no such thing as “indeterminate liability” here. Kerah defines: “[I]f a person is liable [to be defensively killed], it means that she has forfeited her right against being killed in certain circumstances, for a certain reason. Killing her does not wrong her, and she has no right to defend herself against it.” (126) Yet on her own account, none of the drivers has forfeited her right [not to be killed without the other drivers also being killed] (I use the brackets to indicate the scope of the right). If a driver would be killed without also killing the other drivers, he would be wronged (since his death was non-instrumental for achieving a proportionate goal, like saving the life of the pedestrian). However, again on her very own account, all of the drivers have forfeited their different right [not to be killed together with the others]. Killing them together with the others is instrumental. Kerah doesn’t prohibit this killing because the killed are not liable to it (she insists they are), but because it would, allegedly, impose harms on them to which they are not liable, namely the harm of “having the liability justification on the basis of which [they are] killed secured by the killing of other people” (132). Thus, they are all liable to be killed together, while they are not liable to be killed without the others also being killed. There is nothing “indeterminate” about this. Accordingly, the “liability justification on the basis of which [they are] killed” is not “secured” by the killing of other people; rather, there simply IS a “liability justification” for killing any of them together with the others – it need not be “secured” or “created,” it’s just there –, while there is no “liability justification” for killing any of them without the others. In other words: by killing them all, the pedestrian has not made any of the drivers “worse off” by “making” any of them liable to something they have not been liable to all along, and thus Kerah’s argument from “wide proportionality” seems not to get off the ground.
    Let us now step back and have a look at the bigger picture, which raises the question: why would Kerah – or anyone, for that matter – want to defend McMahan’s responsibility account in the first place? After all, the “multiple threats” challenge is the least of its problems. To wit, from the very beginning on McMahan has admitted that his account has counter-intuitive implications. It would imply that the mother of a culpable attacker would be liable to be killed (if the threat cannot be averted otherwise) because she “chose to engage in an activity (having a child) that had a tiny probability of resulting in an unjust threat” and this threat now materialized. McMahan then rightly points out that the mother is not liable, but he claims that “it is less obvious what the right explanation is of why the mother is not liable” (“The Basis of Moral Liability to Defensive Killing,” p. 396.). Actually, the explanation is obvious: McMahan’s account is wrong. I gave a few other counter-examples to his account (“Rights, Liability, and the Moral Equality of Combatants,” pp. 334-335). Here is a different one: Bill produces and sells many hammers, foreseeing (he actually googled “killed with a hammer”) that there is a chance that a criminally insane person will use one of his hammers to kill an innocent person. On McMahan’s account the hammer manufacturer would become liable to defensive force if the threat cannot be otherwise averted. But again, that is absurd.
    It seems that some people think that the account can be tamed by appealing to “minimal responsibility” or to differences in causal contributions. Unfortunately, while the term “minimal responsible threat,” which is also used by Kerah, and the talk about “degrees of responsibility” have recently become fashionable, they do not make much sense within the McMahanian framework. To wit, the moral responsibility account of liability to defensive killing is meant as an alternative to the culpability account. Someone can be morally responsible yet entirely innocent. But unless somebody explains how and by which criteria (and one would also like to hear concrete examples) a minimally responsible morally entirely innocent threat is to be distinguished from a maximally responsible morally entirely innocent threat, “minimal responsibility” simply means responsibility and will thus be of no help to either the mother or the hammer manufacturer. Do not take my word for it, take McMahan’s word for it (he is not talking about the hammer producer although what he says applies): “Although he is responsible for the threat he poses, he is only minimally responsible, by which I mean ‘merely responsible,’ or responsible though not culpable.” (“Proportionality in War”, in The Ethics of War, p. 5, italics added.) I think it would help to avoid a lot of meanwhile rather widespread confusion to then just say “merely responsible” instead of “minimally responsible.”
    The other strategy might be to distinguish different degrees of causal contribution. Of course, it would have to be morally responsible causal contribution. But in the conscientious driver case such contribution did not only come from the driver, but also from the people at the gas station, the car manufacturers, the sales man, and the adult daughter who gave daddy the key he just couldn’t find. Yet, we would hardly deem any of these other people liable although, at least in terms of “but-for-causation” (and, incidentally, also in some other terms), the daughter, the lone guy at the gas station, and the salesman who just sold the car this morning, contributed no less to the threat than the driver himself. At this point, then, one might want to appeal to morally responsible proximate causation. Unfortunately, while thereby we get the daughter of the hook, we also get the hammer producer back on (he is the proximate morally responsible cause since the attacker is insane). In short, we have all reason to believe that the moral responsibility account is beyond saving (even if the multiple threats challenge could be met), and therefore it should simply be abandoned.
    There are a number of other things I disagree with, and which I would like to mention just for the record. Kerah believes, like McMahan, in “liability justifications.” However, liability is one thing, justification is another. Contrary to Kerah, the fact that a threat is “liable to be defensively killed” does not provide a “pro tanto (or defeasible) justification for killing her.” (125) In that context, I also do not accept the whole instrumentalist and internalist background. Nor do I deem it useful to define “liability,” as Kerah does, in such a way that questions like the following are excluded by definitional fiat: can there be symmetrical liability, is one’s liability to a harm dependent on the reason the harm is inflicted for, can one only become liable by forfeiting rights through one’s own responsible action? However, these concerns are peripheral to Kerah’s main argument, so I will not go further into them (nor do I expect Kerah to respond to them here).

  2. Victor Tadros says:

    Hello Kerah,

    thanks for the excellent paper. I have only had time to read this a bit quickly, but I had a question about a premise that appears to give rise to the problem under consideration.

    As I understand it the premise is something like this:

    If X would alone be liable to be killed to achieve some goal, g (saving Victim’s life) in virtue of some property (such as responsibly posing a threat to another person, Victim) and n people have similar properties to X (each poses a threat to Victim in succession), then all n are liable to be killed to achieve g.

    I think that this premise is clearly mistaken, and although many people writing about multiple attackers seem to accept it, I haven’t seen an argument for it.

    Think about a similar idea in other cases, that do not involve responsibility for threats, but where we lack rights. It is often the case that I have no right not to bear some cost for the sake of some goal, but yet if the only way of achieving the goal is to inflict the same cost on many people, we all have a right not to have the cost inflicted on us. For example, suppose that I can build a bridge over a river that will significantly help my community, but it will cost me £100 to build it. I may be required spend the £100, and I thus lack a right not to spend the £100. Furthermore, it might then not infringe my rights to tax me to take the £100 to build the bridge. But that does not imply that if 1 billion people would each have to spend £100 to build the bridge, they would be required to do so. If they were taxed £100 each, this would plausibly violate all their rights.

    I think that we should say the same thing about multiple attackers – the fact that one attacker is liable to be killed to save Victim’s life does not imply that 1billion similarly placed people are each liable to be killed to save Victim’s life.

    Here is a final reason to think that this is true. The solution that you present is ingenious, and I really like it. But that is also its problem. The intuition that it is wrong to kill some number of minimally culpable threats seems grounded in the simple idea that death is very important, and the number of people killed is morally significant. But if that is right, we should be suspicious of ingenious solutions to the problem – the solution should reflect our intuitions about the significance of deaths, and the significance of an aggregation of deaths, more directly.

  3. Sandy Steel says:

    Hello Kerah.

    Thanks for your very interesting paper.

    A possible objection: for every harm the victim the inflicts on each attacker by killing the others – namely, satisfying one of the necessary conditions of the other attackers’ liability – doesn’t each attacker also inflict a similar harm on the victim? Each attacker makes it harder for the victim to establish liability against any particular attacker, by adding a necessary condition on each attacker’s liability. Might the harms not then ‘cancel out’ in the wide proportionality question?

  4. Saba Bazargan-Forward says:

    Hi Kerah. This is an ingeniously argued paper. But I have a worry.

    Replace 999 of the drivers with rolling boulders. That is, suppose that 999 boulders are rolling sequentially toward the pedestrian, prior to the threat that the single driver imposes. The pedestrian, with a bazooka, blows up boulder 1, then boulder 2, and so on. Call this the “driver & 999 boulders case”. (Call the original version, in which there is just one driver and no other threats to the pedestrian, the “original case”. And call the version in which there are 1000 drivers each of whom is a minimally responsible threat, the “1000 drivers case”). In the driver & 999 boulders case, destroying all the boulders makes the driver worse off, since doing so makes her liable to be killed — on your view. But presumably you think the driver has no right that we refrain from making her worse off in this way. Since there’s no general right against this harm, the driver is not liable to it.

    But it seems strange to say that, at the end of the day, when the pedestrian has destroyed all the boulders and killed the driver, that the driver suffered a greater wrong than she would have if she were just a single driver threatening the pedestrian, absent the boulders. Put differently, it seems that on your view, killing the driver is worse when she is preceded by boulders, that it is when she isn’t preceded by boulders. This is a strange consequence.

    You anticipate this kind of criticism. She argue that that killing the driver in the original case is indeed worse than killing the driver in the 1000 drivers case. This is because, in the original case, that driver is in a worse position than any single driver in the 1000 drivers case. This is because in the 1000 drivers case, any given driver is liable to be killed only if the others are killed. But in the original case, the driver is liable to be killed ‘sans phrase’. So by killing all the threats in the 1000 drivers case, the pedestrian worsens the position of each of the thousand drivers more than she worsens the single driver’s position in the original case.

    You can, then, apply this reasoning to the driver & 999 boulders case. With each boulder we destroy, we remove from the driver a benefit – the shield from liability that the presence of each boulder provides. With each boulder we destroy, we worsen her position. So by destroying all the boulders the pedestrian worsens the position of the driver more than she worsens the single driver’s position in the original case. So it actually is worse, you might conclude, to kill the driver when she is preceded by the boulders than when she isn’t.

    Ok. But now suppose we have a choice. The driver & 999 boulders case is occurring to my left, where one pedestrian is threatened. To my right, the original case is occurring, where another pedestrian is threatened. I can only save one pedestrian – the one to my left or the one to my right. What should I do? If you are correct, I have a definitive moral reason to choose the one on my left, and not the one on my right. Why? Because on your view, killing the driver in the driver & 999 boulders case is worse than killing the driver in the original case. But this strikes me as a strange consequence.

    Similarly, suppose that to save either pedestrian, the harm we have to inflict on the drivers is non-lethal. But, suppose that the harm necessary to save the pedestrian on my left – i.e., in the driver & 999 boulders case – is slightly less than the harm necessary to save the pedestrian on my right – i.e., in the original case. (Maybe the difference is: a broken leg versus a broken leg and a broken wrist). If you are correct in your view that it is comparatively worse to harm the driver in the driver & 999 boulder case than it is to harm the driver in the original case, then there is presumably some degree of greater harm we must be willing to accept to avoid what she takes to be the worse outcome. As a result, if you are correct, then when deciding whether to inflict a broken leg on the driver to the left or a broken leg plus a broken wrist to the driver on the right, we might be required to inflict the greater harm. But again, it is difficult to accept this…

  5. Hi all,

    Thank you for joining this discussion of paper my paper! Renee, thanks especially for your really thoughtful précis.

    So, Renee, here’s my response to your “Simultaneous” case:

    I would maintain that whether each of the 1,000 drivers is liable to be killed in this case is indeterminate: it’s indeterminate because whether each is liable depends on what the pedestrian in fact does. If she evaporates the lot, then she secures her liability justification for killing each. If she doesn’t evaporate the lot, then she lacks a liability justification for killing any – since the deaths of all the others are necessary conditions for the liability of each one.

    The same verdict holds, then, both in the original, and in the Simultaneous case. In both, the drivers’ liability is indeterminate because it is contingent on the pedestrian’s not-yet-performed action(s). If she acts (and succeeds, which we’re assuming she would in both cases) the drivers are liable. Otherwise, they’re not.

    Uwe, Victor, Sandy, and Saba: I’ll be back…. (I might not reply to all of you today, but you’ll from me tomorrow, at the latest.)

  6. Hi Saba,

    Oh, I like this case.

    First: you’re right that, on my view, the driver who’s preceded by boulders is harmed (in the comparative sense of being made worse off than she would otherwise be) by the pedestrian in a way that the original, single driver is not. Her (multi-boulder) shield against liability is removed; and the liability justification on the basis of which she’s subsequently killed is secured.

    The boulder-preceded driver has no right against this harm. But her being harmed in this way is an impersonally bad thing – because her death is an impersonally bad thing. (The basis of her liability – agent-responsibility for the pedestrian’s otherwise being accidentally killed – does not make her death any less of a tragedy.) The badness of her death is already accounted for in narrow-proportionality calculations; it doesn’t get counted again in assessing wide proportionality. But the badness of securing the conditions of her liability (and so, the justification on the basis of which she’ll be killed) hasn’t yet been counted, and so does matter for wide proportionality. Multiplied by a thousand, you get a lesser evil prohibition.

    Which is, in the first instance, a sidebar to the challenge to put to me, so….

    Alright: Here’s a wrinkle in the case of the 3rd-party-defender facing two potential victims, one whose killing is over-determined a thousand times over (by 999 threatening boulders, plus a driver); one who’s killing is not. I wonder – does the unpreceded driver in this version possess a shield roughly akin to that of the boulder-preceded driver? Granted, there’s a liability justification for killing her regardless of what the defended does. But whether she’s killed on the basis of that justification is rendered up-for-grabs by what the defender does. So while the unpreceded driver doesn’t stand to be comparatively harmed, but she does stands to reap a symmetrical comparative benefit. I’d really like to say that it’s wash on that basis….

    Re: the broken-leg-plus-broken-wrist variant, I take your point: if the harms of having-the-liability-justification-on-the-basis-of-which-one-is-harmed-secured aggregate in the thousand driver case, then, disaggregated, any one such harm must be enough to outweigh a substantial lesser harm, i.e., that of a broker wrist. On the other hand: there’s a difference between these types of harm, which is that a person has a presumptive (and in this case, by stipulation, unforfeited) right against having her wrist broken. There’s no such right against having the liability justification on the basis of which one is harmed secured. It’s not obvious that the badness of latter harm defeats the wrong of contravening someone’s right against the former harm.

  7. Hi Kerah – Thanks for the interesting and well-constructed paper – and thanks to Renee for the thoughtful and clear précis. (Thanks, too, to the editors of peasoup for the invitation to join the conversation.)

    I praise the paper as “well-constructed” b.c it’s clearly written, carefully argued – and it builds well on the foundation of McMahan’s liability account, offering an inventive strategy to ameliorate one of the account’s more counterintuitive implications. Still, I must agree with Uwe’s critique above re: the paper’s foundations: “why would anyone… want to defend McMahan’s responsibility account in the first place?” – “liability is one thing, justification is another.” (I would add that pro tanto wrongdoing is one thing and all-things considered wrongdoing is another – and justifiability is one thing and justification is another – and excused wrongdoing is one thing and blameworthy wrongdoing is another…)

    A larger set of conceptual tools (what I call a “reasons-based account”) can help us think through cases in terms of pro tanto wrongdoing (which all killings of human beings are, no matter the blame of the human being who was killed), justifiable killings, justified killings (which are not all-things-considered wrong), excused killings, and blameworthy killings.

    For fear of turning this brief comment on Kerah’s excellent paper into a “Hey, here’s MY paper’s idea,” I’ll stop there. (But if anyone is interested, it’s explained in the chapter, “Against Liability,” in the recent Coons/Weber OUP volume on Ethics of Self-Defense.)

    Again, Kerah, many thanks for the paper. I enjoyed reading it.

  8. Hi Victor,

    Thank you so much for reading and for joining in!

    First, just in case, premise you state is one I’ll provisionally accept, albeit with small amendments:

    If X would alone be liable to be DEFENSIVELY killed to achieve some goal, g (saving Victim’s life) in virtue of some property (such as responsibly posing a threat to another person, Victim) and n people have similar properties to X (each poses a threat to Victim in succession), then EACH n is liable to be DEFENSIVELY killed to achieve g.

    “Defensively” because I’ve not thought enough about liability in other contexts (i.e., punishment) to have a view about the truth of the premise, there; “each” rather than “all” because “all” suggests that they’re liable as a group, which is misleading.

    Your bridge example:

    (1) A bridge might be worth the cost of $100; and it might be worth the cost of $100 being fully charged to a single individual.

    (2) But let’s say the cost of that bridge went up to $100,000. (Maybe after Brexit, the tariffs on construction materials skyrocket.) We’ve no grounds to infer from (1) that the bridge is worth the cost of $100,000, nor that it’s worth the cost of $100,000, distributed equally among 1,000 people.

    I of course completely agree. But what we’re doing, in this example, is weighing the good (the bridge) against some function of (i) its total, or aggregate cost, and (ii) its per-capita cost. (Sidebar: in this case we might think the total cost high enough, compared to the original $100 estimate, that it wouldn’t be worth $100,000 distributed over 100,000 people, at a penny a head. That is, we might judge the total cost prohibitive, regardless of the per capita cost.)

    But I don’t think the aggregative considerations that are doing the work in your example have a foothold in liability justifications (at least as the Responsibility Account understands them). Liability justifications proceed through pairwise comparisons: how does the magnitude of harm that the victim would otherwise suffer compare with the magnitude of harm that her defense would inflict on her threatener; what are the victim’s and the threatener’s respective degrees of responsibility for the fact that one of them will be harmed, etc. Whether the threatener has forfeited her right against being defensively harmed depends on the answers to these questions. (Assume that the circumstantial conditions of liability are satisfied.) The aggregate cost, as measured in lives successive pairwise comparisons deem forfeit – this, again, just seems to have no foothold. (The first part of my reply to Saba might be relevant on this point.)

    My worry applies to Jeff’s recent solution to the problem of the 1,000 minimally responsible threateners (MRTs) (in “Liability, Proportionality, and the Number of Aggressors,” in Saba Bazargan and Samuel Rickless, eds., The Ethics of War (New York: Oxford University press, 2017) – his solution aligns, I think, with what you suggest here. (Uwe – thanks for bringing this piece up, first!) I find the basic idea – that 1,000 MRTs are not liable, in the aggregate, to being killed – attractive; as you say, it speaks far more directly to our intuitions than my solution to the problem does. But I’m skeptical about its compatibility with the structure of liability on the Responsibility Account. This strikes me as the bigger bullet to bite.

    Of course, your view of liability to defensive harm has a different structure altogether (that one is liable to harms that one has an enforceable duty to bear). So ‘liability in the aggregate’ looks to be of a piece with your view.

  9. Hi Kerah,

    thanks for the reply. But why think that liability justifications work through pairwise comparisons in the way that you suggest? I know that some people (Frances Kamm; Jeff) have said this, but they haven’t defended it, and I can’t see how to do so. Once we see that one person’s interests can be insufficient to ground a duty to not to achieve some goal, but comparable interests of many people together can ground a duty to achieve that goal, and thus that there are group rights of a kind (rights that exist because a person is a member of a group of people whose interests together ground a duty) we have no reason to accept the pairwise comparison view of liability.

    Think about it this way: the moral importance of each MRT’s interests are weakened because of their responsibility for the threat, and so her interests do not ground a duty not to kill her in the single case. But that says nothing about whether these weakened interests in the aggregate ground a duty not to kill, and thus say nothing about whether killing violates their rights.

    This does not rely on my own view that liability justifications are often grounded in duties (though, of course, the fact that this view can provide a straightforward explanation of the intuition that it is wrong to kill a certain number of MRTs counts in its favour…)

  10. Saba Bazargan-Forward says:

    Hi again Kerah,

    I admire your fortitude in keeping up with this round-robin of comments! I just want to make sure I understand your response to my broken-leg-plus-broken-wrist variant. You say that in the example there is a moral difference between breaking the driver’s leg and breaking his wrist. A broken leg is a harm a right against which he has forfeited. But a broken wrist is *not* a harm a right against which he has forfeited. There is, though, a pro tanto reason to inflict the broken wrist: doing so is the lesser evil. This is because the alternative — inflicting a broken leg on the other driver — treats that driver even worse, given that he was preceded by the boulders. But this pro tanto lesser evil reason might not be substantial enough to override the driver’s right against having his wrist broken. Is this all correct?

  11. Hi Uwe,

    We’ve not met before, have we? It’s nice to meet you on the Internet. Thank you for reading my paper so carefully, and thinking so much about it.

    Below is a response to what I take to be the key internal objection to my paper (which gets unspooled in your subsequent challenges).

    You say (quoted from your comment, lightly edited):

    “[W]hy is the single driver supposed to be liable, while the pedestrian is not? Because…. “‘conscientious walking’ does not impose on anyone a risk comparable to the risk imposed by driving.” (128) Actually, on the basis of her very own account it does. If the conscientious driver can foresee that he might collide with a pedestrian, a pedestrian can foresee that he might collide with a conscientious driver, and… can foresee that thereby she imposes the risk on drivers of securing their liability by walking into their path – after all, if she weren’t there on the street to collide with the car, the driver would not become liable in the first place. So the pedestrian imposes on the driver the risk of securing his liability by being in his path; and on Kerah’s assumptions (130) the pedestrian will then proceed to kill the driver.”

    Here’s one difference: let’s grant (for the moment) your characterization, of the pedestrian as imposing a risk on the driver with her presence. The risks mutually imposed by the driver and the pedestrian are hardly symmetrical in magnitude. The driver imposes a tiny risk of her car going out of control and threatening a bystander’s life. The risk the pedestrian “imposes” is that, IF a driver’s car goes out of control, threatening the her life, and IF, should that occur, she can defend herself by, and only by, killing the driver, and IF in the circumstance, no disproportionate harms would be imposed on third parties (etc.), THEN, she has a liability justification for killing the driver, on which she’s entitled, but presumptively not morally required, to act. A threatened party’s presence is a prerequisite for a threatener’s liability (since it’s a prerequisite for a threatener being a threatener), but it’s pretty far upstream to “securing” a liability justification.

    (To bring out the contrast, think of Renee’s Simultaneous case, where the act of securing the liability justification on the basis of which each driver is killed, and the act of killing each driver, are one and the same.)

  12. Hi Sandy,

    It’s nice to meet you, and thank you for joining in!

    I’m curious — is your question inspired, in part, by Gerald Overland’s paper, “Moral Obstacles” (published in “Ethics,” 2014)? His view, if I remember, is that bystanders who are positioned such that they’ll be significantly harmed if I defend myself against an aggressor, and who therefore make impermissible otherwise justified defensive action, acquire duties to bear extra harms on my behalf. This is grounded in the fact that their presences makes my situation worse (by foreclosing what would otherwise by my best option); this is bad brute luck, the burdens of which should not fall entirely on me but be shared between us.

    (I hope I’m not mangling Overland’s view; it’s been a while since I’ve read the paper.)

    I have to admit — while I liked the paper, the whole line of thinking of bystanders as harming or disadvantaging me by *being there* leaves me cold.

    This isn’t a response, I realize, but — well, Jon Quong claims the opposite (in his “Ethics” paper of 2009): that people have presumptive property rights over whatever space they occupy at a given time; which give them special rights to defend that space. (The context…. actually, doesn’t matter for the purposes.)

    I’m bringing it up because — the views are near opposites. One says that your occupying a given space grounds special duties; the other that it grounds special rights. Why should we believe one over the other? (Or: why should we believe that the mere fact of being in a particular place has moral salience, of either valence?)

  13. Hi Michelle,

    Thanks for joining the discussion; it’s nice to meet you, and I’m so pleased you liked the paper!

    I’ve not read yours, yet, and so can’t really speak to your alternative – but I’m intrigued, and glad you drew my attention to it.

    I agree with both you and Uwe that this isn’t the place for me to offer a general defense of the Responsibility Account. But: I advance one elsewhere, namely, in the paper “What Makes a Person Liable to Defensive Harm?” (Forthcoming in “Philosophy and Phenomenological Research,” The reason I “want to defend McMahan’s responsibility account in the first place” is that I think it’s largely right; the forthcoming paper makes the case.

  14. Hi Kerah,

    Thanks for your reply (and, like Saba, I admire your ability to keep up with all of these comments).

    So it sounds like you consider it indeterminate whether the drivers in Simultaneous are liable, *because* the pedestrian has not yet acted; once she does hit the button, it is no longer contingent whether she will act (and by stipulation, succeed in self-defense), and therefore no longer indeterminate whether the drivers are liable.

    That does secure symmetry between the 1,000 Drivers and Simultaneous, but I’m worried about this move for two reasons:

    1. It seems to imply that if the pedestrian decides not to defend herself, she *thereby* renders the threatener not liable, making self-defense impermissible. But liability-based defensive permissions seem like the sort of thing that can endure despite deciding not to defend oneself, with the success condition understood counterfactually (if she were to defend, she would succeed) rather than as a question about the defender’s actions in the actual world. At least it doesn’t seem like a conceptual confusion to say that a pedestrian may choose not to defend herself against a genuinely liable (but minimally responsible) threatener.

    2. More centrally, giving this answer to the Simultaneous case forces us (I think) to say that whether the single driver in the original case is liable is indeterminate until the Pedestrian acts defensively. The single driver’s liability is, after all, also contingent on the success of the Pedestrian’s not-yet performed actions.

    But if that’s so, then the thousand and the single driver are made worse off in the same type of way by the Pedestrian’s defensive action: she secures a liability that had previous been indeterminate. If we still need to say that the thousand are harmed more, then we will need to be able to make sense of how the numbers matter to the harm involved in securing liability. A naive way to do this is to count the harm as worse the more ‘shields’ one loses, such that a driver in the thousand drivers case is 10x more harmed than a driver in an otherwise parallel 100 driver case. But this strategy doesn’t look promising: it’s hard to see how a button that vaporizes each of the thousand threats at once harms each *by rendering them determinately liable* more than a button that vaporizes each of a hundred threats at once.

    Of course if we can’t make these comparisons compelling, then the claim that the thousand are each harmed comparatively more than the single driver looks tenuous.

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