A friend of mine argued that, once implantation has occurred, the pregnant woman is an incubator for this life — a life that will likely become independent of her – and therefore should not destroy it. I think advocates of that position must also value potential people generally.
Consider 4 scenarios:
1. we destroy the fertilized egg right after it attaches to the wall of the uterus
2. we destroy the fertilized egg in the fallopian tube before it reaches the uterus
3. we destroy the fertilized egg immediately after conception
4. we destroy the egg (or sperm) just before conception would have occurred
I don’t see these scenarios as much different. In my opinion, it makes sense for people to find all 4 scenarios either morally objectionable or acceptable.
If one objects to all 4 scenarios, that suggests they value potential life (as in scenario 4). I would guess, then, that anti-abortion folks should be in favor of a world with a large population. They should favor bringing into the world as many people that could exist that our resources can support (or as many that can exist without causing life to have negative value).
However, I do not think it is obvious that potential people will benefit from existing. The antinatalist position is at least worth considering. One could argue that, since most living people would say they are glad they’re alive, that that is sufficient evidence for existence having positive value. However, species that do not want to live would become extinct pretty quickly. Even most very depressed people would fight for their lives if they were attacked. So, I wonder if we are good judges about the value of our existence. Even if we were miserable, the desire to live might be so great that we would deceive ourselves into thinking we are glad we exist.
Even if life does have positive value for most existing people (which I think is probably the case), the value of life for potential people who do not yet exist, and especially ones that would not exist without a policy change (e.g., banning abortion), should not be thought of as following the same distribution of value as people who already exist. There is selection bias at work here. In addition, the existence of new people potentially affects the quality of life of existing people (people who want an abortion think this new life will have a negative impact on their own life).
One other thing to note: even if you object to all 4 of the above scenarios, you still might prefer that they are all legal options. I’m not discussing that aspect of it here.