Welcome to the third Journal of Moral Philosophy discussion here at PEA Soup. It 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:
- 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.
- Necessity: the harm-producing act must be necessary for bringing about this good.
- 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.