I think it’s wrong for us to kill innocent people. Some fellow deontologists, however, think this prohibition should be restricted to say that it’s wrong for us to kill nonconsenting innocent people. These thinkers hold that it is both permissible to consent to being killed and to kill those who have given such consent (except in special cases, such as when the victim has overriding unfulfilled duties to others).
I want to argue for a curious consequence of this restriction of the prohibition of murder while maintaining deontology.
By “sacrificing one’s life to save lives”, I will mean actions which save lives but have one’s own death as an unintended but foreseen side-effect. For instance, jumping in front of a train to push a child out of the way. Everyone agrees it’s typically praiseworthy, and hence permissible, to sacrifice your life to save an innocent life. Most people, however, will say that it is supererogatory to do so. It is brave to do it, but not cowardly to omit it.
But now consider cases where by sacrificing your life you can save a larger number of innocent lives, say a dozen. It is pretty plausible that it would be cowardly to refrain from the sacrifice, and I suspect it would be wrong to do it except in special cases (such as when you have just figured out how to cure cancer). But I agree that the point is not completely clear to me. However, it is quite clear to me that it would be wrong to refuse to sacrifice your life to save a dozen people when that dozen includes one’s spouse and one’s children (again, with some very rare exceptions).
Now let’s assume the view that it is permissible to consent to being killed and permissible to kill the consenting. Consider a classic deontology case: a terrorist says that if you don’t kill Bob, a dozen other innocent people will be killed. Add that the dozen people include Bob’s spouse and children. If it’s permissible to kill the consenting, then if Bob were to consent, it would be permissible to kill him. But Bob expressly and clearly refuses consent, despite his believing that it would be permissible to consent.
Assuming that it is morally required to sacrifice your life to save a dozen innocent lives when these lives include your spouse and children, it is very difficult to deny that if it is permissible to consent to being killed, in a case like the above, Bob would be morally required to consent to being killed. Granted, the sacrifice case does not include consenting to one’s death, while the terrorist case does. But as long as we have granted that it is permissible to consent to one’s death, the difference does not seem significant. Thus Bob is morally required to consent to being killed, given our assumptions about consensual killing. Bob’s refusal of consent is thus morally wrong. And very badly so: it causes eleven more lives to be lost, including his very own spouse and children. His refusal is about as bad as mass murder!
It seems that Bob is far from innocent. On the contrary, he is guilty of refusing to save the lives of eleven people, including his spouse and children. But now it seems that the prohibition against killing the innocent does not apply to Bob, and hence it is permissible—and maybe even obligatory—to kill Bob. If so, then the deontological prohibition on killing the innocent, if restricted to the nonconsenting, has a giant loophole: when enough is at stake, a nonconsenting victim is no longer innocent! Now, maybe, it is only permissible to kill the guilty when one acts on behalf of a state (and when enough is stake, which it is in this case). But it would still be very strange for a deontologist to think it permissible to kill Bob even should the state authorize it.
This is not a knockdown argument against the restriction of the prohibition of murder to nonconsenting victims. But it is some evidence against the restriction.