The Trolley Problem / Das Trolley-Problem (Englisch/Deutsch). Judith Jarvis Thomson

it otherwise would be), or let it be the case that A kills five. And the supposition that it would be worse for B to choose [88]to kill the one is entirely compatible with the supposition that killing five is worse than killing one. Again, the alternatives open to the surgeon are: Operate on the one, thereby saving five (and making the surgeon’s own moral record better than it otherwise would be), or let it be the case that he himself will have killed the five. And the supposition that it would be worse for the surgeon to choose to operate is entirely compatible with the supposition that killing five is worse than killing one.

      On the other hand, suppose a second surgeon is faced with a choice between here and now giving chemical X to five, thereby killing them, and operating on, and thereby killing, only one. (It taxes the imagination to invent such a second surgeon, but let that pass. And compare Trolley Driver.) Then, other things being equal, it does seem he may choose to operate on the one. Some people would say something stronger, namely that he is required to make this choice. Perhaps they would say that

      (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

      [90]is a quite general moral truth. Whether or not the second surgeon is morally required to make this choice (and thus whether or not (II’) is a general moral truth), it does seem to be the case that he may. But this did seem puzzling. As I put it: Why should the present tense matter so much?

      It is plausible to think that the present tense matters because the question for the agent at the time of acting is about the present, viz. “What may I here and now do?,” and because that question is the same as the question “Which of the alternatives here and now open to me may I choose?” The alternatives now open to the second surgeon are: kill five or kill one. If killing five is worse than killing one, then perhaps he ought to, but at any rate he may, kill the one.