Monday, August 21, 2023

Two looping trolley scenarios

As part of an argument against the Principle of Double Effect, Thomson argued that if one thinks that it is permissible to redirect a trolley that is heading towards a branch with five people (“Branch” in my diagram) so it heads on a branch towards one, then this redirection remains permissible if one adds a looping track to the right branch that comes back to the left branch, as long as the one person on the right branch is large enough to stop the trolley from hitting the five.

But, Thomson insists, in the looping case the trolley’s hitting the large person on the right branch is a means to the five being saved, and so the defender of Double Effect cannot hold that there is something especially bad about intentionally harming someone.

Subsequently, it’s been noted, implicitly or explicitly (Liao et al.) that there is an ambiguity in Thomson’s story. On one version, “SymLoop” in my diagram, the track becomes symmetric, so that just as the one would block the trolley from hitting the five if the trolley went to the right branch, the five would block the trolley from hitting the one if the trolley stayed on the left branch. On the other hand, in AsymLoop, the left branch continues on, and if the trolley were to go on the left branch without the five being there, inertia would carry it harmlessly forward and away from everyone concerned.

When talking about all looping trolleys with Harrison Lee, it has occurred to me that there is a not implausible view on which:

  1. Redirection in Branch is permissible.

  2. Redirection in SymLoop is permissible.

  3. Redirection in AsymLoop is impermissible.

Here is why. In Branch, we have the standard Double Effect considerations, which I won’t rehearse.

Now, redirecting in AsymLoop is morally the same as a case where a trolley is heading down a straight unbranching path towards five people, and you grab a random large bystander and push them in front of the trolley to save the five (call this “Bystander Push”). For in both AsymLoop and Bystander Push, you are interposing a bystander between the trolley and the five. The only difference is the mechanics of who or what is moved (and motion is relative anyway). And most non-utilitarians agree that pushing the bystander in front of the trolley is wrong.

However, SymLoop is a bit different. Here we have six people towards whom a dangerous trolley is heading, and we try to rearrange the six people in danger in such a way that as few of them die as possible. What is analogous to SymLoop is not Bystander Push, but a case where the trolley is heading down a single straight path in a narrow tunnel (so narrow that stepping off the track won’t save one), on which there are five small people just in front of one large person, and we reorder the large person to be in front of the small ones. Call this Reorder Push.

I think there is good reason to think Reorder Push is permissible. We have a group in danger. By chance, the status quo is that the five small people are protecting the large person. But is that fair? They are smaller in body, but no smaller in dignity. If they were all the same size, so that no matter what order they were in, the same number would die, it would be fair to roll dice to figure out the order—or to just count the status quo as “the dice having already been rolled”. But when they are not the same size, there is a naturally preferred arrangement of the people in danger: the large one first, and then the small ones. (For a variant case, suppose the six people are all standing in a line in the tunnel perpendicular to the track, so that when the trolley comes, they all will die. It would be perfectly reasonable for the five small ones to move behind the one large one, and utterly unreasonable for the large one to move behind the five small ones—the large person shouldn’t get defended at the expense of five.)

If Reorder Push is permissible, so is redirection in SymLoop. In both cases, the trolley is heading towards six, and we are just rearranging.

Now, it may seem that the reasoning behind Reorder Push should be rejected by a non-consequentialist. But I don’t think so. Prior to learning of Thomson’s Loop case (and hence not in order to generate a response to Loop), I wrote a paper on Double Effect where using an idea of Murphy’s I defend a distinction between accomplishing someone’s death and accomplishing someone’s being in lethal danger. On the view I defend, it’s always wrong to accomplish someone’s death, at least under such conditions as juridical innocence, but accomplishing someone’s being endangered, even lethally, is not always wrong. In particular, it’s not always wrong when the person consents to it, or when one has appropriate authority over the person. Thus, just as it is permissible to jump on a grenade to save comrades, it is permissible to push someone on a grenade with with their consent (suppose that the hero is unable to themselves jump, and the person pushing the hero is unable to reach the grenade with their own body), and it may be permissible for an officer to push a non-consenting soldier onto the grenade.

Now, the trolley case is not a case of intentional killing but of intentionally setting up a situation that in fact has lethal danger in it. One does not intend the death of the one in redirecting the trolley, but instead one intends the absorption of kinetic energy—which absorption happens to be a lethal danger to the absorber. This is not absolutely morally forbidden, but is only forbidden in some cases. In particular, it is not forbidden in cases of consent. That’s why pushing a random bystander is wrong, but it is not wrong to push a volunteer who is otherwise unable to move. In the same way, redirection in either SymLoop or AsymLoop would be permissible with the consent of the large person on the right track. But as the case is normally set up, you don’t have this consent.

Now, without the consent of the large person, AsymLoop and SymLoop come apart, as do Bystander and Reorder Push. Grabbing someone towards whom the trolley is not heading, and putting them in front of the trolley, whether by pushing (Bystander Push) or by moving the trolley (AsymLoop) is a wrongful case of accomplishing their lethal endangerment. But when that person happens to be in the lucky status quo where they are in the path of the trolley, but are being protected by the bodies of the five, they ought to refuse that costly protection. They ought in justice to consent to reordering or redirection. Now, in some cases, actual consent and obligation-in-justice to consent have different moral effects (e.g., in sexual cases the difference is very significant), but in other cases they may have similar moral effects. It is quite reasonable to say that in endangerment cases, actual consent and obligation to consent have similar moral effects. (One hint of this is that endangerment cases are ones where authority can have an effect to consent; sexual cases, for instance, are not like that—authority does nothing in the absence of consent there.) Thus, even without consent, redirection in SymLoop is permissible—but not so in AsymLoop.

Final remark: I wonder if it matters whether it is justice or something else that requires the consent in these kinds of cases. Intuition: One has a moral duty to jump in front of a trolley that is heading towards a hundred (but mabe not towards five) people. If so, and if it doesn’t matter whether the obligation is in justice or in some other way (say, charity), then once enough lives come to be at stake, then redirection in AsymLoop and pushing the non-consenting bystander become permissible. But if the obligation has to be one of justice, then one might hold that the redirection and pushing remains wrong even when there are more lives at stake.

Acknowledgment: The thinking here is greatly influenced by arguments from Harrison Lee about volunteering in loop trolley cases, but the conclusions differ.

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