Inquiring as to intentions

Thomson and other opponents of the idea that intention deeply affects moral permissibility like to point to the idea that it is silly to think that when having someone perform some task, we need to figure out what intentions they would have, when the intentions don’t affect how they will act. To use Thomson’s example, it seems silly to think that when you ask a doctor to administer a dose of morphine to a terminally ill patient where you foresee that any dose sufficient to remove the pain is also sufficient to cause death, you need to find out whether the doctor intends death by the dose or intends to play by Double Effect rules and only pursue pain-relief. As long as in both cases the doctor will give the same dose and in the same way, it doesn’t matter what they are intending when we ask them to act.

If this line of argument shows that intentions don’t affect permissibility, it proves too much. For suppose that you need a nurse to give a patient an injection of a small amount of morphine after an operation. You know there are only two nurses around. One of them is a murderer who swapped the vial of morphine in the dispensary for cyanide. Fortunately, you caught the swap, and reversed it. Unfortunately, you don’t yet know which of the two nurses is which. Suppose you know for sure that both nurses will inject the morphine equally well, but one of them will be committing attempted murder with it, thinking that it’s cyanide. It seems to me that if one is impressed by Thomson’s argument in the foreseeably lethal dose of morphine case, one should also think that in this case it doesn’t matter which nurse one chooses (as long as you know that both will do the same task the same way, and that the murderous nurse won’t swap the vial again). But in this case it is clear that it matters: one nurse would be committing attempted murder and the other wouldn’t. And we should avoid bringing it about that someone will commit attempted murder.

What about a more extreme case? Alice deeds an injection to live. Only Bob is qualified to do it. Bob, however, wants Alice dead. But Bob is mistakenly convinced that the vial of life-saving medicine is a vial of cyanide. Is it permissible to ask Bob to perform the injection?

That’s tough. Still, even if we say it’s permissible, I think it’s very plausible that it should be a last resort: if there were another to administer the injection, we should go for the other.

I am inclined to think it’s not permissible. For one’s action plan depends on Bob's attempting murder (that’s why we don’t correct his error about the vial!), and it’s wrong to intend that someone attempt murder.