For me, ethics are supposed to provide a guide for how to live in real life, so far-fetched hypotheticals will have proportionate impact on my views (which in this case, is to say low). As far as I know, poisoning unfertilized egg cells by way of excessive alcohol consumption does not happen, but I've been wrong before.

I do accept the need to answer hypotheticals though, even if they are unlikely or even impossible, as a way to sharpen the boundaries of moral claims and learn about their applicability and potential short comings.

In response to paragraph 5: in a very broad sense, Brandy may have affected many bodies through the purchase and consumption of alcohol, though it cannot be said that she harmed her own fetuses since she was not pregnant at the time. When I say the "mere existence" of FAS, I mean FAS as it exists in real life, and should only be applied to women who are pregnant at the time of their alcohol consumption (or the consumption of another substance dangerous to the unborn).

Paragraph 6 makes me worry that I have misunderstood you, though I am not sure where I would have done that. The FAS point is meant to address the specific claim that when a woman opts for an abortion, that she is acting upon only her body (which I can't tell if you believe), FAS shows that her choices clearly are influencing a separate body. I brought this point to your attention because I think it demonstrates that a fetus' future has moral value, at least if you accept that drinking heavily while pregnant is harmful.

If a woman took a substance that poisoned her unfertilized eggs in such a way as to guarantee FAS once she became pregnant, but she goes on to never get pregnant, then I do not see anything harmful, at least as it relates to the parameters of our debate.

If she does go on to become pregnant however, and her fetus has FAS, then I do not see the issue with saying that her decision to take that substance was harmful in retrospect, since she reduced the possibilities of happiness for that fetus (someone with FAS may very well live a happy life, only that this likelihood is reduced) once it was conceived. I do not see the ordering of events as critical. Events may not manifest their harm until deep in the future, and require other triggering events in order to be harmful at all, and affect people that did not exist at the time of the event. But those people, at that time, are no longer hypothetical, though they were at the time the event took place.

I suspect this will need clarification. Let's total all the contingent people, combinations of egg and sperm, and call it quantity X (it is a spectacularly large number). Those X people are contingent, and strictly speaking do not exist at all, they are only theoretical, you might even say fictional. However, some of those gamete combos will actually come to pass. At that point, past events that harm them can be described as "harmful". Otherwise they cannot.

But wouldn't that make contingent humans morally valuable? No. The actual humans that are harmed in the future matter. Take for example efforts to mitigate global warming. I do not believe that contingent humans can be harmed, but I do believe that the humans who will live in the future, whoever they may be, can be harmed at the time they exist. Now, the precise number and circumstances of these humans is speculative for me, but moral choices can be made on a speculative basis (expected return). If I calculate that there will be future people, and that those future people will be harmed by global warming, then I can measure my moral response to that belief.

This argument probably requires that moral time be seen as flat, though the past is likely unchangeable, and to see that the "harmfulness" of an act is something that might dangle in limbo for centuries.

Your last question is complicated. At the time of her drinking, there is no harmed fetus. Once she becomes pregnant, there is a body harmed by a past action, the harm being the deprivation of health, now, and in the future. That action was made harmful by the conception of the fetus, whereas it would have remained harmless otherwise.

Harm requires context. Future events can provide needed context in order to identify past/present events as harmful. If the relevant future events are prevented, than a certain past event can remain harmless.

So what should a woman with poisoned eggs do? If she calculates that her child will still live a life worth living, despite its FAS, she should try to conceive if she wants to, and regret her choice to consume whatever substance led her to this condition since it likely diminished her child's life, and if she can change that past, she should (though this is likely impossible). If she calculates that such a child will live a miserable life (a very hard burden to meet in practice) then she should avoid conceiving. Such a calculation could also justify an abortion while we are at it, but in practice, this calculation is rarely satisfied. This calculation could also justify the merciful murder of born people, but again, it is rare to be so confident in someone's future misery.

Contingent people can be harmed once they cease to be contingent and become actual.

You could say in response, "but doesn't that mean that your present actions, say to pollute the environment, are harming contingent people (besides the actual people who exist in the present)?" No. I calculate that some of those contingent people will become actual people, and that they will say retroactively that my pollution was harmful to them, and at that point, they would be correct.

A fetus is an actual human, not a hypothetical one. A present action that diminishes its future, such as killing it, harms it by way of deprivation. That harm is manifested as time goes on and the deprivation accumulates (if you knew when this fetus would have died, you can stop the clock at that point).

However, a human in the present can look forward, and see that their present action will bring about the future harm of deprivation, just like how present choices to destroy the environment have predictable and acute future harms of deprivation. Seeing these future harms, speculative though they are, we should seek to mitigate them. BUT if we knew for certain that there would be no future for humans at all, say we knew the Earth would blow up in an hour, then these concerns would likely fade, since those X theoretical persons don't matter, and there will be no actual persons to worry about.

Another example might make things clearer. When Abraham Lincoln was in the process of abolishing slavery, he thought about slaves that had not yet been born. He wasn't worried about merely potential people, but people who will be actual in the future, and suffer.

The desired end-state for me is to make abortion redundant by making unplanned pregnancy nearly 0 through sex-ed and contraceptive access, and by making the welfare state more comprehensive. These things are good for many reasons, one of them being that they reduce abortions (much more so than abortion restrictions in fact).

I look forward to a long series of exchanges. Though I cannot always take the time to respond quickly, sometimes it may take me a few days.