Friday, September 16, 2022

Proportionality in Double Effect and prevention cases

Suppose you are visiting a hospital and you see Bob, a nurse, sneaking into Alice’s hospital room. Unnoticed, you look at what is going on, and you see that Bob is about to add a lethal drug to Alice’s IV, a drug that would undetectably kill Alice while leaving her organs intact. You recall with horror that two days ago you had a conversation with Bob and he described to you how compelling he finds the argument that it is sometimes obligatory to kill one patient in order to provide organs to save multiple other patients, when this can be done secretly. At the time, you unsuccessfully tried to persuade Bob that the consequentialism behind the argument was implausible. You happen to know that if Bob were to die right now, then four people could be saved. You could now yell, push Bob away, and prevent Alice’s murder.

Here is a Double Effect argument that you shouldn’t stop the murder. Your action of pushing Bob away has two sets of effects: (a) Alice isn’t murdered and (b) four patients who would be saved by Alice’s organs die. Of these, (a) is an intended good and (b) is an unintended evil. So your action is an action to which Double Effect is relevant: it is an action with two effects, an intended good and an unintended evil. But Double Effect makes it a necessary condition for the permissibility of an action that the evils not be disproportionate to the goods. And here the evils are disproportionate to the goods. So you shouldn’t stop Bob, it seems.

Now, one might question the proportionality judgment. Maybe while four deaths are disproportional to one death, four deaths are not disproportionate to one murder? This is mistaken, however. For suppose you see an assassin trying to murder someone with a long-range shot, and you see four innocent people near the assassin. The only way you have to stop the assassin is with a hand-grenade, which would kill the four innocents as well. It is clear that four deaths of innocents are disproportionate to the one murder: you should not stop the murder by blowing up the assassin.

Suppose you bite the bullet and agree that you shouldn’t stop Bob. Then I have an even more problematic version. Go back to your disquieting conversation with Bob about killing patients for their organs. Suppose that Bob disclosed to you in the course of that conversation that it wasn’t a merely hypothetical question, as you assumed, but that he was actually planning on acting on it. It seems completely clear that you should try to persuade him out of this murderous plan. But the exact same Double Effect argument seems to apply here: There are two sets of effects of your persuading Bob not to do it—one person isn’t murdered and a number of people die. The bad effects are disproportionate to the good ones, so Double Effect seems to prohibit you from persuading Bob out of his plan.

Maybe though this second case is different from the first, in that it is one of the basic tasks of a fellow human being to persuade others to act well—this is a central part of our human communal interaction. So it may be that once we take into account the good of persuading others to act well, and add that good to the intended goods, now the four deaths are no longer disproportionate. But now increase the numbers. Perhaps Alice has some weird mutation in her heart tissue such that culturing her heart tissue would save a thousand lives. Now the death of a thousand seems clearly disproportionate to preventing one murder and obtaining the goods of persuading others to act well. Imagine that I had a choice between preventing an explosion that would completely destroy a ship with a thousand people on board and persuading someone not to commit an “ordinary” murder. I should prevent the sinking of the ship. Yet even in the thousand patient case I have the intuition—admittedly, now weaker—that I should try to persuade Bob not to murder Alice, or at least that it is permissible to do so. Especially if Bob is my friend.

What’s going on? Is it the case that when we consider the good of persuading someone to act well, we should not count against that any goods that would result from their acting badly? Is it—a graduate student suggested this to me—that if I fail to persuade them to act well in order to obtain the goods that would result from their act badly, then I become complicit in their bad action? I think there is something to this idea. It may even apply in my earlier case of not stopping Bob physically from the murder, but it seems particularly plausible in the case of refraining to persuade.

In any case, if I am right that it is right to persuade Bob out of his plan to murder Alice, we really do need to understand the proportionality condition in Double Effect very carefully. That condition seems to become significantly context-sensitive. Double Effect is not a simple structural principle by any means.

Objection: When it’s a matter of stopping Bob’s murder of Alice, you don’t cause the deaths of the patients who need Alice’s organs to live. The patients die of whatever conditions they die of, rather than from your action.
So those deaths don’t figure in the Double Effect proportionality calculus.

Response: Imagine that I could stop an ordinary murder, but to do that I would have to park my car in a place that would block an ambulance from getting to the scene of an unrelated accident, where a number of people would die of their injuries if the ambulance were not to get there in time. When considering my action of parking my car, I do need to consider the deaths of the people the ambulance would save, even though they die from their injuries rather than from my action. If the number of people the ambulance would save is large enough, I ought not block the ambulance’s path to prevent one murder.


entirelyuseless said...

Another option is to defend Alice with a lethal blow to Bob's head. Which then allows you to save the other lives too.

Helen Watt said...


If you do push Bob away merely to save Alice, all deaths are side-effects but if you don't, formal cooperation lurks if you are refraining to benefit transplant recipients. Maybe I'm missing something but this looks as if you share Bob's plan - both his end (lives saved with Alice's organs) and his means (Alice killed by Bob).

In contrast, take another case: Police Officer Olly who omits to intervene to stop a riot in a suburb, because doing so will merely drive the rioters into the inner city area. Intervening would be futile overall in that it would merely result in more rioting and homicides.

Olly is not like another police officer, George, who intends that deaths occur in the suburbs - say, as a warning to the inner city. Olly omits to protect the suburb not to enable suburb homicides but simply because intervening would do more harm than good. True, Olly plans to benefit the inner city by his non-intervention, at least in the sense that he eschews what does them harm, but he is not 'using' the suburb like Bob is using Alice or you seem to be using Alice if you let Bob go ahead precisely so organ recipients can live.

To make the transplant case more like Olly - imagine your non-intervention is simply motivated by an intention that Bob not run amok in the children's ward. Again, intervening is futile overall - Bob has powerful friends who work in the children's ward and though you would save Alice, several children would be killed for their organs.

Here you share none of Bob's wrongful plans to achieve what you nonetheless welcome in failing to intervene: the saving of lives with Alice's organs. You are intending to save children, not intending to enable Bob to save adults by killing Alice.

Alexander R Pruss said...


In the Bob and Alice case, it seems that if you don't stop Bob, you need not have any plan besides "Don't violate Double Effect!" It seems you are refraining from stopping Bob precisely because stopping Bob would violate proportionality in Double Effect.

Alexander R Pruss said...


Yeah, but if you use lethal force to stop Bob when non-lethal force would do the job, now it looks like you're murdering Bob.