Brain-in-a-vat Trolley Question

Just saw this on an­other fo­rum. I figured I’d re­post it here, since it’d be in­ter­est­ing to see you guy’s an­swer to it.

Con­sider the fol­low­ing case:

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.

QUESTION: What should the brain do?

[ALTERNATIVE EXAMPLE: Same as above, ex­cept the brain has had a com­mi­suro­tomy, and the left half of the brain is a con­se­quen­tial­ist and the right side is an ab­solutist.]