Suppose I deliberately endanger you, but the danger doesn't befall you. Then there is a sense in which I do you no harm, but there is also a sense in which imposing the danger on your was a harm to you. You have a claim against me for my endangerment of you.
But one can also endanger people who never exist. For instance, if I give you a drug that has a high probability of physically harming your future children if you have any (let's say I assign a certain moderate probability to your having children), but you never actually have any children. There I might be harming you in some way, but I don't harmed them, since they never exist to be harmed. One can tweak the case so there are no parents to be harmed. Maybe I expect intelligent life to evolve on some planet with moderate probability, and I set up a device to harm some intelligent beings on that planet once they evolve, but no life evolves there.
There are thus two probabilities in endangerment. There is the probability that there is going to be potential victims at all and the conditional probability that a potential victim will be harmed given that there is going to be a potential victim at all. And the probability of harm is the product of these two probabilities.
It is a very interesting question whether there is a significant moral difference between a case where
- I deliberately cause a probability 1/4 of harm to a person I know for sure to exist
- I deliberately cause a probability 1/2 of (same as above) harm to a person I assign probability 1/2 to the existence of (i.e., I deliberately cause it to be the case that if that person exists, she has chance 1/2 of suffering that harm)
The consequentialist intuitions that we all have to some degree pull one to saying that there is no difference. On the other hand, in the first case there is a person that I have failed to love and respect her in the way that she deserves, while there is no such failure of love and respect in the second case. In fact, if one has a picture of morality as essentially involving interpersonal relations, it is difficult to see how any wrongdoing has happened in the second case if in fact the person never comes to exist.
A theist might be able to maintain both something like the consequentialist intuition and the idea that moral failures are primarily failures of interpersonal relations. There is a deep and mysterious message in Scripture expressed by the Psalmist saying to God: "Against you, you alone, have I sinned" (Ps 51.4). The Psalm heading connects this with David's sin against Uriah, which makes this message particularly puzzling, since it seems clear that David sinned against both Uriah and God. But suppose we take really seriously the idea that all positive attributes are acts of participation in God. Uriah's dignity, then, is an act of participation in God's dignity, and its value entirely derivative from God's infinite dignity. In some sense, then, David's wrongdoing against Uriah really just is a wrongdoing against God. Now suppose that David had been wrong, and there never had been a Uriah. (Maybe Bathsheba was an unmarried woman who created a myth of an Uriah in order to protect herself from unwanted advances.) The wrongdoing against God's dignity would have been just the same. The wrongdoing against Uriah wouldn't have been there, but that wrongdoing's "culpatory force" was entirely derivative from the culpatory force of the wrongdoing against God, since Uriah's dignity was an act of participation in God's dignity. If we have something like this picture, then we really can say that all moral failures are primarily failures of interpersonal relations and yet hold the two cases, the one where there is an endangered victim and the one where there turns out not to be one, to be morally on par. For all respect and love is ultimately and implicitly for God, though perhaps God qua participated in or participable in by a creature.