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Citation: 94 Yale L. J. 1984-
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The Trolley Problem
Judith Jarvis Thomsonf
I.
Some years ago, Philippa Foot drew attention to an extraordinarily in-
teresting problem." Suppose you are the driver of a trolley. The trolley
rounds a bend, and there come into view ahead five track workmen, who
have been repairing the track. The track goes through a bit of a valley at
that point, and the sides are steep, so you must stop the trolley if you are
to avoid running the five men down. You step on the brakes, but alas they
don't work. Now you suddenly see a spur of track leading off to the right.
You can turn the trolley onto it, and thus save the five men on the straight
track ahead. Unfortunately, Mrs. Foot has arranged that there is one
track workman on that spur of track. He can no more get off the track in
time than the five can, so you will kill him if you turn the trolley onto
him. Is it morally permissible for you to turn the trolley?
Everybody to whom I have put this hypothetical case says, Yes, it is.^2
Some people say something stronger than that it is morally permissible for
you to turn the trolley: They say that morally speaking, you must turn
it-that morality requires you to do so. Others do not agree that morality
t Professor of Philosophy, Massachusetts Institute of Technology. B.A., Barnard College 1950, Cambridge University 1952; M.A., Cambridge University 1956; Ph.D., Columbia University 1959. Many people have given me helpful criticism of this essay's many successive reincarnations over the years; I cannot list them all-for want of space, not of gratitude. Most recently, (^) it benefited from criticism by the members of the Yale Law School Civil Liability Workshop and the Legal Theory Workshop, Faculty of Law, University (^) of Toronto.
1. See P. FOOT, (^) The Problem of Abortion and the Doctrine of the Double Effect, in VIRTUES AND VICES AND OTHER ESSAYS IN MORAL PHILOSOPHY 19 (1978).
- I think it possible (though by no means certain) that John Taurek would say No, it is not permissible to (all simply) turn the trolley; what you ought to do is flip a coin. See Taurek, Should the Numbers Count?, 6 PHIL. & PuB. AFF. 293 (1977). (But he is there concerned with a different kind of case, namely that in which what is in question is not whether we may do what harms one to avoid harming five, but whether we may or ought to choose to save five in preference to saving one.) For criticism of Taurek's article, see Parfit, Innumerate (^) Ethics, 7 PHIL. & PUB. AFF. 285 (1978).
Trolley Problem
So the surgeon must refrain from operating. By contrast, (^) the trolley driver's choice is between turning the trolley, in which case he kills one, and not turning the trolley, in which case he does not let five die, he
positively kills them. Now surely we can say
(II) Killing five is worse than killing one.
But then that is why the trolley driver may turn his trolley: He would be doing what is worse if he fails to turn it, since if he fails to turn it he kills five. I do think that that is an attractive account of the matter. It seems to me that if the surgeon (^) fails to operate, he does not kill his five patients who need parts; he merely lets them die. By contrast, if the driver fails to turn his trolley, he does not merely let the five track workmen die; he drives his trolley into them, and thereby kills them. But there is good reason to think that this problem is not so easily solved as that. Let us begin by looking at a case that is in some (^) ways like Mrs. Foot's story of the trolley driver. I will call her case Trolley Driver; let us now consider a case I will call Bystander at the Switch. In that case you have been strolling by the trolley track, and you can see the (^) situation at a glance: The driver saw the five on the track ahead, he stamped on the brakes, the brakes failed, so he fainted. What to do? Well, here is the switch, which you can throw, thereby turning the trolley yourself. Of course you will kill one if you do. But I should think you may turn it all the same.^5 Some people may feel a difference between these two cases. (^) In the first place, the trolley driver is, after all, captain of the trolley. He is charged by the trolley company with responsibility for the safety of his passengers and anyone else who might be harmed by the trolley he drives. The by- stander at the switch, on the other hand, is a private person who just happens to be there. Second, the driver would be driving a trolley into the five if he does not turn it, and the bystander would not-the bystander will (^) do the five no harm at all if he does not throw the switch. I think it right to feel these differences between the cases. Nevertheless, my own feeling is that an ordinary person, a mere by- stander, may intervene in such a case. If you see something, a trolley, a boulder, an avalanche, (^) heading towards five, and you can deflect it onto
5. A similar case (intended to make a point similar to the one that I shall be making) is discussed in Davis, The Priority of Avoiding Harm, in KILLING AND LETTING DIE 172, 194-95 (B. Steinbock ed. 1980).
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one, it really does seem that-other things being equal-it would be per- missible for you to take charge, take responsibility, and deflect the thing, whoever you may be. Of course you run a moral risk if you do, for it might be that, unbeknownst to you, other things are not equal. It might be, that is, that there is some relevant difference between the five on the one hand, and the one on the other, which would make it morally prefera- ble that the five be hit by the trolley than that the one be hit by it. That would be so if, for example, the five are not track workmen at all, but Mafia members (^) in workmen's clothing, and they have tied the one work- man to the right-hand track in the hope that you would turn the trolley onto him. I won't canvass all the many kinds of possibilities, for in fact the moral risk is the same whether you are the trolley driver, or a by- stander at the switch. Moreover, second, we might well wish to ask ourselves what exactly is the difference between what the driver would (^) be doing if he failed to turn the trolley and what the bystander would be doing if he (^) failed to throw the switch. As I said, the driver would be driving a trolley into the five; but what exactly would his driving the trolley into the five consist in? Why, just sitting there, doing nothing! (^) If the driver does just sit there, doing nothing, then that will have been how come he drove his trolley into the five. I do not mean (^) to make much of that fact about what the driver's driving his trolley into the five would consist in, for it seems to me to be right to say that if he does not turn the trolley, he does drive his trolley into them, and does thereby kill them. (Though this does seem to me to be right, it is not easy to say exactly what makes it so.) By contrast, if the bystander does not throw the switch, he drives no trolley into anybody, and he kills nobody. But as I said, my own feeling is that the bystander may intervene. Per- haps it will seem to some even less clear that morality requires him to turn the trolley than that morality requires the driver to turn the trolley; perhaps some will feel even more discomfort at the idea of the bystander's turning the trolley than at the idea of the driver's turning (^) the trolley. All the same, I shall take it that he may. If he may, there is serious (^) trouble for Mrs. Foot's thesis (I). It is plain that if the bystander throws the switch, he causes the trolley to hit the one, and thus he kills the one. It is equally plain that if the bystander does not throw the switch, he does not cause the trolley to hit the five, he does not kill the (^) five, he merely fails to save them-he lets them die. His choice therefore is between throwing the switch, in which case he kills one, and not throwing the switch, in which case he lets five die. If thesis (I) were
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We tend to forget that some killings themselves include lettings die, and do include them where the act by which the agent kills takes time to cause death-time in which the agent can intervene but does not. In face of these possibilities, the question arises what we (^) should think of thesis (II), since it looks as if it tells us that the surgeon ought to oper- ate, and thus that he may permissibly do so, since if he operates he kills only one instead of five. There are two ways in which we can go here. First, we can say: (II) does tell us that the surgeon ought to operate, and that shows it is false. Second, we can say: (II) does not tell us that the surgeon ought to operate, and it is true. For my own part, I prefer the second. If Alfred kills five and Bert kills only one, then questions of motive apart, and other things being equal, what Alfred did is worse than what Bert did. If the surgeon does not operate, so that he kills five, then it will later be true that he did some- thing worse than he would have done if he had operated, killing only one-especially if his killing of the five was murder, committed out of a desire for money, and his killing of the one would have been, though mis- guided and wrongful, nevertheless a well-intentioned effort to save five lives. Taking this line would, of course, require saying that assessments of which acts are worse than which other acts do not by themselves settle the question what it is permissible for an agent to do. But it might be said that we ought to by-pass (II), for perhaps what Mrs. Foot would have offered us as an explanation of why the driver may turn the trolley in Trolley Driver is not (II) itself, but something more complex, such as
(II') If a person is faced with a choice between doing something here and now to five, by the doing of which he will kill them, and doing something else here and now to one, by the doing of which he will kill only the one, then (other things being equal) he ought to choose the second alternative rather than the first.
We may presumably take (II') to tell us that the driver ought to, and hence permissibly may, turn the trolley in Trolley Driver, for we may presumably view the driver as confronted with a choice between here and now driving his trolley into five, and here and now driving his trolley into one. And at the same time, (II') tells us nothing at all about what the surgeon ought to do in Transplant, for he is not confronted with such a choice. If the surgeon operates, he does do something by the doing of which he will kill only one; but if the surgeon does not operate, he does not do something by the doing of which he kills five; he merely fails to do
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something by the doing of which he would make it be the case that he has not killed five. I have no objection to this shift in attention from (II) to (II'). But we should not overlook an interesting question that lurks here. As it might be put: Why should the present tense matter so much? Why should a person prefer killing one to killing five if the alternatives are wholly in front of him, but not (or anyway, not in every case) where one of them is partly behind him? I shall come back to this question briefly later. Meanwhile, however, even if (II') can be appealed to in order to ex- plain why the trolley driver may turn his trolley, that would leave it en- tirely open why the bystander at the switch may turn his trolley. For he does not drive a trolley into each of five if he refrains from turning the trolley; he merely lets the trolley drive into each of them. So I suggest we set Trolley Driver aside for the time being. What I shall be concerned with is a first cousin of Mrs. Foot's problem, viz.: Why is it that the bystander may turn his trolley, though the surgeon may not remove the young man's lungs, kidneys, and heart? Since I find it particu- larly puzzling that the bystander may turn his trolley, I am inclined to call this The Trolley Problem. Those who find it particularly puzzling that the surgeon may not operate are cordially invited to call it The Transplant Problem instead.
IV. It should be clear, I (^) think, that "kill" and "let die" are too blunt to be useful tools for the solving of this problem. We ought to be looking within killings and savings for the ways in which the agents would be carrying them out. It would be no surprise, I think, if a Kantian idea occurred to us at this point. Kant said: "Act so that you treat humanity, whether in your own person or in that of another, always as an end and never as a means only." It is striking, after all, that the surgeon who proceeds in Trans- plant treats the young man he cuts up "as a means only": He literally uses the young man's body to save his five, and does so without the young man's consent. And perhaps we may say that the agent in Bystander at the Switch does not use his victim to save his five, or (more generally) treat his victim as a means only, and that that is why he (unlike the surgeon) may proceed. But what exactly is it to treat a person as a means only, or to use a person? And why exactly is it wrong to do this? These questions do not have obvious answers. 6
6. For a sensitive discussion of some of the difficulties, see Davis, Using Persons and Common
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Let us now imagine that the five on the straight track are thin, but thick enough so that although all five will be killed if the trolley goes straight, the bodies of the five will stop it, and it will therefore not reach the one. On the other hand, the one on the right-hand track is fat, so fat that his body will by itself stop the trolley, and the trolley will therefore not reach the five. May the agent turn the trolley? Some people feel more discom- fort at the idea of turning the trolley in the loop variant than in the origi- nal Bystander at the Switch. But we cannot really suppose that the pres- ence or absence of that extra bit of track (^) makes a major moral difference as to what an agent may do in these cases, and it (^) really does seem right to think (despite the discomfort) (^) that the agent may proceed. On the other hand, we should notice that the agent here needs the one (fat) track workman on the right-hand track if he is to save his five. If the one goes wholly out of existence just before the agent starts to turn the trolley, then the agent cannot save his fiveS-just as the surgeon in Trans- plant cannot save his five if the young man goes wholly out of existence just before the surgeon starts to operate. Indeed, I should think that there (^) is no plausible account of what is involved in, or what is (^) necessary for, the application of the notions "treat- ing a person as a means only," or "using one to save five," under which the surgeon would be doing this whereas the agent in this variant of By- stander at (^) the Switch would not be. If that is right, then appeals to these notions cannot (^) do the work being required of them here.
V.
Suppose the bystander at the switch proceeds: He throws the switch, thereby turning the trolley onto the right-hand track, thereby causing the one to be hit by the trolley, thereby killing him-but saving (^) the five on the straight track. There are two facts (^) about what he does which seem to me to explain the moral difference between what (^) he does and what the agent in Transplant would be doing if he proceeded. In the first place, the by- stander saves his five by making something that threatens them instead threaten one. Second, the bystander does not do that by means which themselves constitute an infringement of any right of the one's. As is plain, then, my hypothesis as to the source of the moral difference between the cases makes appeal to the concept of a right. My own feeling
8. It is also true that if the five go wholly out of existence just before the agent starts to turn the trolley, then the one will (^) die whatever the agent does. Should we say, then, that the agent uses one to save five if he acts, and uses five to save one if he does not act? No: What follows and is false. If the agent does not act, he uses nobody. (I doubt that (^) it can even be said that if he does not act, he lets them be used. For what is the active for which this is passive? Who or what would be using them (^) if he does not act?).
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is that solving this problem requires making appeal to that concept-or to some other concept that does the same kind of work. 9 Indeed, I think it is one of the many reasons why this problem is of such interest to moral theory that it does force us to appeal to that concept; and by the same token, that we learn something from it about that concept. Let us begin with an idea, held by many friends of rights, (^) which Ron- ald Dworkin expressed crisply in a metaphor from bridge: Rights "trump" (^) utilities.^10 That is, if one would (^) infringe a right (^) in or by acting, then it is not sufficient justification for acting that one would thereby maximize utility. It seems to me that something like this must be correct. Consideration of this idea suggests the possibility of a very simple solu- tion to the problem. That is, it might be said (i) The reason why the surgeon may not proceed in Transplant is that if he proceeds, he maxi- mizes utility, for he brings about a net saving of four lives, but in so doing he would infringe a right of the young man's. Which right? Well, we might say: The right the young man has against the surgeon that the surgeon not kill him-thus a right in the cluster of rights that the young man has in having a right to life. Solving this problem requires being able to explain also why the by- stander may proceed in Bystander at the Switch. So it might be said (ii) The reason why the bystander may proceed is that if he proceeds, he maximizes utility, for (^) he brings about a net saving of four lives, and in so doing he does not infringe any right of the one track workman's. But I see no way-certainly there is no easy way-of establishing that these ideas are true. Is it clear that the bystander would infringe no right of the one track workman's if he turned the trolley? Suppose there weren't anybody on the straight track, and the bystander turned the trolley onto the right-hand track, thereby killing the one, but not saving anybody, since nobody was at risk, and thus nobody needed saving. Wouldn't that infringe a right of the one workman's, a right in the cluster of rights that he has in having a right to life? So should we suppose that the fact that there are five track workmen on the straight track who are in need of saving makes the one lack that right-which he would have had if that had not been a fact? But then why doesn't the fact that the surgeon has five patients who are in need of saving make the young man (^) also lack that right? I think some people would say there is good (excellent, conclusive) rea- son for thinking that the one track workman lacks the right (given there
9. I strongly suspect that giving an account of what makes it wrong to use a person, see supra text accompanying notes 6-8, would also require appeal to the concept of a right.
- R. DWORKIN, TAKING RIGHTS SERIOUSLY ix (1977).
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No doubt it is permissible to turn the trolley, but still... but still .... People who feel this discomfort also think that, although it is permissible to turn the trolley, it is not morally required to do so. My own view is that they are right to feel and think these things. We would be able to explain why this is so if we supposed that if the bystander turns the trol- ley, then he does do the one track workman a wrong-if we supposed, in particular, that he infringes a right of the one track workman's which is in that cluster of rights which the workman has in having a right to life.1 1 I do not for a moment take myself to have established that (ii) is false. I have wished only to draw attention to the difficulty that lies ahead of a person who thinks (ii) true, and also to suggest that there is some reason to think that the bystander would infringe a right of the one's if he pro- ceeded, and thus some reason to think that (ii) is false. It can easily be seen that if there is some reason to think the bystander would infringe a right of the one's, then there is also some reason to think that (i) is false-since if the bystander does infringe a right of the one's if he pro- ceeds, and may nevertheless proceed, then it cannot be the fact that the surgeon infringes a right of the young man's if he proceeds which makes it impermissible for him to do so. Perhaps a friend of (i) and (ii) can establish that they are true. I pro- pose that, just in case he can't, we do well to see if there isn't some other way of solving this problem than by appeal to them. In particular, I pro- pose we grant that both the bystander and the surgeon would infringe a right of their ones, a right in the cluster of rights that the ones' have in having a right to life, and that we look for some other difference between the cases which could be appealed to to explain the moral difference be- tween them. Notice that accepting this proposal does not commit us to rejecting the idea expressed in that crisp metaphor of Dworkin's. We can still say that rights trump utilities-if we can find a further feature of what the by- stander does if he turns the trolley (beyond the fact that he maximizes utility) which (^) itself trumps the right, and thus makes it permissible to proceed.
VI.
As I said, my own feeling is that the trolley problem can be solved only by appeal to the concept of a right-but not by appeal to it in as simple a way as that discussed in the preceding section. What we were attending to
11. Many of the examples discussed by Bernard Williams and Ruth Marcus plainly call out for this kind of treatment. See B. WILLIAMS, Ethical Consistency, in PROBLEMaS OF THE SELF 166 (1973); Marcus, Moral Dilemmas and Consistency, 77 J. PHIL. 121 (1980).
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in the preceding section was only (^) the fact that the agents would be killing and saving if they proceeded; what we should be attending to is the means by which they would kill and save."^2 (It is very tempting, because so much simpler, to regard a human act as a solid nugget, without internal struc- ture, and to (^) try to trace its moral value to the shape of its surface, as it were. The trolley problem seems to me to bring home that that will not do.) I said earlier that there seem (^) to me to be two crucial facts about what the bystander does if he proceeds in Bystander at the Switch. In the first place, (^) he saves his five by making something that threatens them instead threaten the one. And second, he does not do that (^) by means which them- selves constitute infringements of any right (^) of the one's. Let us begin with the first. If the surgeon proceeds in Transplant, he plainly does not save his five by making something that threatens them instead threaten one. It is or- gan-failure that threatens his five, and (^) it is not that which he makes threaten the young man if he proceeds. Consider another of Mrs. Foot's cases, which I shall (^) call Hospital.
Suppose [Mrs. (^) Foot says] that there are five patients in a hospital whose lives (^) could be saved by the manufacture of a certain gas, but that (^) this will inevitably release lethal fumes into the room of another patient whom for some reason we are unable to move."
Surely it would not be permissible for us to manufacture the gas. In Transplant and Hospital, the five at risk are at risk from their ail- ments, and this might be thought to make a difference. Let us by-pass it. In a variant on Hospital-which (^) I shall call Hospital'-all six patients are convalescing. The five at risk are at risk, not from their ailments, but from the ceiling of their room, which is (^) about to fall on them. We can prevent this (^) by pumping on a ceiling-support-mechanism; but doing so will inevitably release lethal fumes into the room of the sixth. Here too it is plain we may not proceed. Contrast a case in which lethal fumes are being released by the heating
- It may be worth stressing that what I suggest calls for attention is not (as some (^) construals of "double effect" would have it) whether the agent's killing of the one is his means to something, and not (as other construals of "double effect" would have it) whether the death of the one is the agent's means to something, but rather what are (^) the means by which the agent both kills and saves. For a discussion of "the doctrine of double effect," see P. FooT, supra note 1. 13. Id. at 29. As Mrs. Foot says, we do not use the one if we proceed in Hospital. Yet the impermissibility (^) of proceeding in Hospital seems to have a common source with the impermissibility of operating in Transplant, in which the (^) surgeon would be using the one whose parts he takes for the five who need them. This is my second reason for thinking that an appeal to the fact that the surgeon would be using his victim is an over-simple way of taking account of the means he would be (^) employ- ing for the saving (^) of his five. See supra note 7.
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VII.
More precisely, it is not morally required of us that we let a burden descend out of the blue onto five when we can make it instead descend onto one if we can make it descend onto the one by means which do not themselves constitute infringements of rights of the one. Consider a case-which I shall call Fat Man-in which you are stand- ing on a footbridge over the trolley track. You can see a trolley hurtling down the track, out of control. You turn around to see where the trolley is headed, and there are five workmen on the track where it exits from under the footbridge. What to do? Being an expert on trolleys, you know of one certain way to stop an out-of-control trolley: Drop a really heavy weight in its path. But where to find one? It just so happens that standing next to you on the footbridge is a (^) fat man, a really fat man. He is leaning over the railing, watching the trolley; all you have to do is to give him a little shove, and over the railing (^) he will go, onto the track in the path of the trolley. Would it be permissible for you to do this? Everybody (^) to whom I have put this case says it would not be. But why? Suppose the agent proceeds. (^) He shoves the fat man, thereby toppling him off the footbridge into the path of the trolley, thereby (^) causing him to be hit by the trolley, thereby killing him-but saving the five on the straight track. Then it is true of this agent, as it is true of the agent in Bystander at the Switch, that he saves his five by making something which threatens them instead threaten one. But this (^) agent does so by means which themselves constitute an in- fringement of a right of the one's. For shoving a person is infringing a right of his. So also is toppling a person off a footbridge. I should stress that doing these things is infringing a person's rights even if doing them does not cause his death-even if doing (^) them causes him no harm at all. As I shall put it, shoving a person, toppling a person off a footbridge, (^) are themselves infringements of rights of his. A theory of rights ought to give an account of what makes it be the case that doing either of these things is itself an infringement (^) of a right of his. But I think we may take it to be a datum that it is, the job which confronts the theo- rist of rights being, not to establish that it is, but rather to explain why it is. Consider by contrast the agent in Bystander at the Switch. He too, if he proceeds, saves five by making something that threatens them instead threaten one. But the means he takes to make that be the case are these: Turn the trolley onto the right-hand track. And turning the trolley onto the right-hand track is not itself an infringement of a right of anybody's. The agent would do the one no wrong at all if he turned (^) the trolley onto the right-hand track, and by some miracle the trolley did not hit him.
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We might of course have imagined it not necessary to shove the fat man. We might have imagined that all you need do to get the trolley to threaten him instead of the five is to wobble the handrail, for the handrail is low, and he is leaning on it, and wobbling it will cause him (^) to fall over and off. Wobbling the handrail would be impermissible, I should think-no less so than shoving. But then there is room for an objection to the idea that the contrast I point to will help explain the moral differences among these cases. For it might be said that if you wobble the handrail, thereby getting the trolley to threaten the one instead of the (^) five, then the means you take to get this to be the case are just these: Wobble the hand- rail. But doing that is not itself an infringement of a right of anybody's. You would do the fat man no wrong at all if you wobbled the handrail and no harm came to him in consequence of your doing so. In this respect, then, your situation seems to be exactly (^) like that of the agent in Bystander at the Switch. Just as the means he would be taking to make the trolley threaten one (^) instead of five would not constitute an infringement of a right, so also would the means you would be taking to make the trolley threaten one instead of five not constitute an infringement of a right. What I had in mind, however, is a rather tighter notion of "means" than shows itself in this objection. (^) By hypothesis, wobbling the handrail will cause the fat man to topple onto the track in the path of the trolley, and thus will cause the trolley to threaten him instead of the five. But the trolley will not threaten him instead of the five unless wobbling the hand- rail does cause him to topple. Getting the trolley (^) to threaten the fat man instead of the five requires getting him into its path. You get the trolley to threaten him instead of them by wobbling the handrail only if, and only because, by wobbling the handrail you topple him into the path of the trolley. What I had in mind, then, is a notion of "means" which comes out as follows. Suppose you get a trolley to threaten one instead of five by wob- bling a handrail. The means you take to get the trolley to threaten the one instead of the five include wobbling the (^) handrail, and all those further things that you have to succeed in doing by wobbling (^) the handrail if the trolley is to threaten the one instead of the five.
So the means by which the agent in Fat Man gets the trolley to threaten (^) one instead of five include toppling the fat man off the footbridge; and doing that is itself an infringement of a right of the fat man's. By contrast, the means by which (^) the agent in Bystander at the Switch gets the trolley to threaten one instead (^) of five include no more than getting the trolley off the straight track onto the right-hand track; and doing that is not itself an infringement of a right of anybody's.
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The Yale Law Journal
to do so if the Mayor had not issued his invitation and guarantee. The Mayor was out for a walk; he now stands by the switch.^14
For the Mayor to get the trolley to threaten the one instead of the five, he must turn the trolley onto the right-hand track; but the one has a right against the Mayor that he not turn the trolley onto the right-hand track-a right generated by an official promise, which was then relied on by the one. (Contrast the original Bystander at the Switch, in which the one had no such right.) My own feeling (^) is that it is plain the Mayor may not proceed. To my great surprise, I find that some people think he may. I conclude they think the right less stringent than I do. In any case, that distributive exemption that I spoke of earlier is very conservative. It permits intervention into the world to get an object that already threatens (^) death to those many to instead threaten death to these few, but only by acts that are not themselves gross impingements on the few. That is, the intervenor must not use means that infringe stringent rights of the few in order to get his distributive intention carried out. It could of course be argued that the fact that the bystander (^) of the origi- nal Bystander at the Switch makes threaten the one what already threat- ens the five, and does so by means that do not themselves constitute in- fringements of any right of the one's (not even a trivial right of the one's), shows that the bystander in that case infringes no right of the one's at all. That is, it could be argued that we have here that independent ground for saying that the bystander does not infringe the one's right to life which I said would be needed by a friend of (ii).^15 But I see nothing to be gained by taking this line, for I see nothing to be gained by supposing it never permissible (^) to infringe a right; and something is lost by taking this line, namely the possibility (^) of viewing the bystander as doing the one a wrong if he proceeds-albeit a wrong it is permissible to do him.
Ix.
What counts as "an object which threatens death"? What (^) marks one threat off from another? I have no doubt that ingenious people can con- struct cases in which we shall be unclear whether to say that if the agent proceeds, he makes threaten the one the very same thing as already threatens the five.
- Notice that in this case too the agent does not use the one if he proceeds. (This case, along with a number of other cases I have been discussing, comes from Thomson, Killing, Letting Die, and the Trolley Problem, 59 THE MoNis 204 (1976). Mrs. Thomson seems to me to have been blunder- ing around in the dark in that paper, but the student of this problem may possibly find some of the cases she discusses useful.). 15. See supra text accompanying notes 9-11.
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Trolley Problem
Moreover, which are the interventions in which the agent gets a thing that threatens five to instead threaten one by means that themselves con- stitute infringements of stringent rights of the one's? I have no doubt that ingenious people can construct cases in which we shall all be unclear whether to say that the agent's means do constitute infringements of strin- gent rights-and cases also in which we shall be unclear whether to say the agent's means constitute infringements of any rights at all. But it is surely a mistake to look for precision in the concepts brought to bear to solve this problem: There isn't any to be had. It would be enough if cases in which it seems to us unclear whether to say "same threat," or unclear whether to say "non-right-infringing-means," also seemed to us to be cases in which it is unclear whether the agent may or may not proceed; and if also coming to see a case as one to which these expressions do (or do not) apply involves coming to see the case as one in which the agent may (or may not) proceed.
X.
If these ideas are correct, then we have a handle on anyway some of the troublesome cases in which people make threats. Suppose a villain says to us "I will cause a ceiling to fall on five unless you send lethal fumes into the room of one." Most of us think it would not be permissible for us to accede to this threat. Why? We may think of the villain as part of the world around the people involved, a part which is going to drop a burden on the five if we do not act. On this way of thinking of him, nothing yet threatens the five (certainly no ceiling as yet threatens them) (^) and a fortiori we cannot save the five by making what (already) threatens them instead threaten the (^) one. Alternatively, we may think of the villain as himself a threat to the five. But sending the fumes in is not making him be a threat to the one instead of to the five. The hypothesis I proposed, then, yields what it should: We may not accede. That is because the hypothesis I proposed says nothing at (^) all about the source of the threat to the five. Whether the threat to the five is, or (^) is caused by, a human being or anything else, it is not permissible to do what will kill one to (^) save the five except by making what threatens the five itself threaten the one. By contrast, it seems to me very plausible to think that if a villain has started a trolley towards five, we may deflect the trolley towards one-other things being equal, of course. If a trolley is headed towards five, and we can deflect it towards one, we may, no matter who or what caused it to head towards the five. I think that these considerations help us in dealing with a question I drew attention to earlier. Suppose (^) a villain says to us "I will cause a
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