The Bystander at the Switch case is a fundamental part of Thomson’s argument in “Trolley Problem.” The basis of her paper is to explain the moral difference between this case, which she deems morally permissible (1398), and the Transplant case, which she deems morally impermissible (1396). In the Bystander at the Switch case, a bystander sees a trolley hurtling towards five workers on the track and has the option of throwing a switch to divert the trolley’s path towards only one worker. Thomson finds the Bystander at the Switch case permissible under two conditions:
1) first, that the same threat is diverted from a larger to a smaller group of people, and
2) second, that the means by which this threat is diverted does not in itself constitute an infringement of anyone’s rights (1407).
However, in order for her thesis to be correct, the Bystander at the Switch case must always be morally permissible. There should be no situation in which it is morally impermissible to kill the one and save the five. If there were such a situation, where both parts of Thomson’s thesis remained true but it would still be morally impermissible to kill the one because of some outside factor, then Thomson’s thesis would no longer be the complete answer.
Let’s consider the Mother-Son case. The trolley is still hurtling towards five workers. Here, the bystander is a woman who has the option of throwing a switch to divert the path of the trolley towards only one person. In this case, however, that one person happens to be her son. Is it still morally permissible for her to throw the switch? I would have to say no.
However, in this case, the decision of flipping the switch to divert the path of the trolley still satisfies both of Thomson’s conditions. First, the threat of the trolley is being diverted from a larger to a smaller group of people, from the five to the one. And second, no one’s rights are being infringed upon.
It may be argued that the son has a stringent right not to be killed by his own mother, and by flipping the switch, the mother would be infringing on this right and therefore not satisfy Thomson’s second condition. However, Thomson does concede that even in the Bystander in the Switch case, the bystander does infringe a right of the one’s (1406), but she justifies this by distinguishing the outcome of the action from the means by which the outcome was achieved. In other words:
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. (Thomson 1409)