Saturday, July 2, 2011

Trolley Problems, or A Great Way to Spend My Time

DarwinCatholiclinked to a great Trolley Problem that I just had to draw in Paint.

On Twin Earth, a brain in a vat is at the wheel of a runaway trolley. There are only two options that the brain can take: the right side of the fork in the track or the left side of the fork. There is no way in sight of derailing or stopping the trolley and the brain is aware of this, for the brain knows trolleys. The brain is causally hooked up to the trolley such that the brain can determine the course which the trolley will take.

On the right side of the track there is a single railroad worker, Jones, who will definitely be killed if the brain steers the trolley to the right. If the railman on the right lives, he will go on to kill five men for the sake of killing them, but in doing so will inadvertently save the lives of thirty orphans (one of the five men he will kill is planning to destroy a bridge that the orphans’ bus will be crossing later that night). One of the orphans that will be killed would have grown up to become a tyrant who would make good utilitarian men do bad things. Another of the orphans would grow up to become G.E.M. Anscombe, while a third would invent the pop-top can.

If the brain in the vat chooses the left side of the track, the trolley will definitely hit and kill a railman on the left side of the track, ‘Leftie,’ and will hit and destroy ten beating hearts on the track that could (and would) have been transplanted into ten patients in the local hospital that will die without donor hearts. These are the only hearts available, and the brain is aware of this, for the brain knows hearts. If the railman on the left side of the track lives, he too will kill five men, in fact the same five that the railman on the right would kill. However, ‘Leftie’ will kill the five as an unintended consequence of saving ten men: he will inadvertently kill the five men rushing the ten hearts to the local hospital for transplantation. A further result of ‘Leftie’s’ act would be that the busload of orphans will be spared. Among the five men killed by ‘Leftie’ are both the man responsible for putting the brain at the controls of the trolley, and the author of this example. If the ten hearts and ‘Leftie’ are killed by the trolley, the ten prospective heart-transplant patients will die and their kidneys will be used to save the lives of twenty kidney-transplant patients, one of whom will grow up to cure cancer, and one of whom will grow up to be Hitler. There are other kidneys and dialysis machines available; however, the brain does not know kidneys, and this is not a factor.

Assume that the brain’s choice, whatever it turns out to be, will serve as an example to other brains-in-vats and so the effects of his decision will be amplified. Also assume that if the brain chooses the right side of the fork, an unjust war free of war crimes will ensue, while if the brain chooses the left fork, a just war fraught with war crimes will result. Furthermore, there is an intermittently active Cartesian demon deceiving the brain in such a manner that the brain is never sure if it is being deceived.

What should the brain do?
Excerpted from:
– Michael F. Patton Jr., “Tissues in the Profession: Can Bad Men Make Good Brains Do Bad Things?”, Proceedings and Addresses of the American Philosophical Association, January 1988

I think that drawing diagrams is a great way to work through complex problems.

When I drew this crazy thing out, I noticed right away that the 5 people are doomed and the orphans will be saved in either scenario. Thank goodness, the author of the problem and the idiot who put a brain in charge of a trolley are doomed along with an orphan murderer (too bad for you, 2 other nameless victims). We're now guaranteed to have a tyrant queen Orphan Annie, a GEM Anscombe Orphan, and an Inventor-of-the-Pop-Tab Orphan grow to maturity.

So, I blocked out that whole section.

What if the brain KNEW about the extra 20 kidneys outside the scenario? It could block out that whole section, like this...

Then there's an unjust war with no war crimes, a just war with war crimes, 10 people who will or won't receive heart transplants, a nice man and a mean man. Under a strictly utilitarian scenario, the justness or unjustness of the wars may not matter if they kill different numbers of people or render them unhappy or if the "wrong" side wins. Outcomes, not justifications, are important. The war crimes sound really bad, but if the war crimes are committed against fewer people than the regular waging of the other war happens to kill, then a purely utilitarian brain would favor the criminal war. Since the brain doesn't know the numbers, it can't make a decision, and would ignore that section of the problem.

In this case, we can see that sending the trolley down the right side of the tracks will kill only one man and save 11.

HOWEVER, remember that I said that the brain is actually ignorant of kidneys, so it would NOT ignore the kidney patient problem.

I used the World Health Organization estimation of cancer deaths in 2008 to factor the worth of a cure for cancer. For Hitler, I used 12,000,000 deaths from the Holocaust (6 million Jews + 6 million others-- Gypsies, political prisoners, disabled people, etc), a number I may have underestimated, especially if you put in all the millions killed in combat in WWII. In 2 years, according to a utilitarian brain in a vat, a cure for cancer would "balance out" the Holocaust, so it would send the trolley down the LEFT side, killing the nice man, destroying the hearts, and allowing the 20 kidney patients to be saved. The brain was ignorant and made the "wrong" choice.

All this, of course, ignores both the Cartesian demon confusing the brain intermittently and the unknown ultimate effects of the brain's choice on the other brains.


I just realized the brain may be ignorant of all future outcomes of the people involved in these scenarios (from the car crashes on). If so, one might think it would kill the man on the right to save the 10 heart patients and the man on the left. If the brain is a strict utilitarian ignorant of kidneys (other than that each person has 2), though, it will destroy the hearts of 10 (plus the man on the left) so that the kidneys of 20 might be saved. So it will send the trolley down the left.


  1. Pedantic ClassicistJuly 3, 2011 at 7:29 AM

    The brain breaks the system by figuring out (using its superior biav powers) how to throw ITSELF in front of the trolley, allowing all the lives saved/lost on BOTH sides to play out.

    "...I never took the Kobayashi Maru test until now. What do you think of my solution?"

  2. Pedantic ClassicistJuly 3, 2011 at 7:46 AM

    On a more serious note.

    While I've always liked ethical quandary /hypothetical/YOUCANTWIN!!/ type thingees as thought experiments, I think I just realized why they are always ultimately flawed. In hypotheticals like this one, the decider is always given a bunch of information about the future choices of the potential casulties/salvandi. By presenting the choices in this omniscient/outside-of-time perspective, the free will of these agents is removed. In "real life", however, there is no way to know what the person or his descendent WILL do. Thinking about all of these potential outcomes is useful, I suppose, for figuring out one's priorities, but I don't think it really helps one make better choices. There is no way to see all ends. Even Agatha in Minority Report, who has a real gift for seeing future actions, believes in the ultimate sovereignty of choice, right up until the point when you do something.

    In short, why is the question always whether you would kill young Hitler or let him live? I think converting him would be a much better choice.

    Ummm, on a somewhat less serious note. Who else thinks that the Cartesian demon would look better with a Descartes-esque mustache? ;)

  3. Hmm, a man with the charisma of Hitler and the conscience of Dorothy Day...yes, that would have been great.

    I added an update to deal with the "what if the brain doesn't know the fates of the people in question" problem and it ultimately ends the same way.

  4. The only solution is to have, or imagine yourself having, a beer...

  5. A runaway trolley is headed down the tracks. On the left side, it will smash into a truck that is being loaded with stout, destroying all the beer. On the right side, it will smash into your favorite pale ale, with the same effect. Which beer do you destroy? What if there is a 83% chance that the other company will be grateful and give you a lifetime supply of their product? Does it make a difference if Hitler has just bought stock in one of them? What if THAT SAME ONE that Hitler likes is on the way to a hospital for teenagers who are dying of a rare disease and their only Make-a-Wish is to taste alcohol before they go?

  6. When I tried to puzzle this one out using non-utilitarian ethics, I came up against the Cartesian demon issue. I initially decided that if the brain knows the Cartesian demon exists it negates moral responsibility for choice. The brain is not merely in the situation of someone who doubts their perceptions are real and hypothesises a Cartesian demon - it is in the position of someone who knows that their perceptions are being manipulated by an outside force. However, I realised this incorrect - the demon only negates personal responsibility if it is a.) malicious and b.) active at times of its own choosing. In this case the demon (assuming 'malicious' means 'will always choose to turn the brain's decisions to evil') will always intervene at the crucial juncture and warp the brain's perceptions so when it thinks it is choosing the good outcome it is in fact choosing the evil one. If the demon is a.) malicious and b.) randomly active, then even if it is deceiving the brain 50% of the time, choosing the good results in a 50% chance of a good outcome; choosing the evil results in a 0% chance of a good outcome. If the demon is a.) capracious, randomly choosing to deceive the brain for good and other times for evil, a 50% active demon only has a 25% chance of twisting a good choice to evil. If the demon is a.) capracious and b.) always intervenes at the moment of critical choice, then he will subvert a good choice 50% of the time but support it the other 50% of the time.

    The Cartesian demon issue becomes more interesting if it is malicious and active 80%, 90%, 99% of the time. It becomes worthwhile to distinguish between the 'malign' (who deceives the brain for evil) and 'contrary' (which deceives the brain to do the opposite of what it intends) demons. If one knows of the existence of a contrary demon operating more than 50% of the time, but do not know when it is active, does one have a moral responsibility to do evil, knowing the contrary demon must pervert these actions to the good? If the malign demon, is it ever morally justifiable to cease attempt to choose the good? If the malign demon is active 100% of the time, is it permissible to choose evil in the certain knowledge that choosing good is pointless?