I used the term "realizing its full potential as being a sentient being", by which I meant achieving full sentience and being sapient. Even short of realizing its full potential the zygote would have that unrealized potential in a way that a sperm cell does not.
I consider becoming a human (even a very immature, undeveloped, and in a sense primitive one) to be an important distinction even without realized sentience. Which doesn't mean that realizing sentience can't also be an important distinction, humans at different stages of their development are reasonable treated differently. Infants or even young adolescents aren't allowed to vote or drive or sign binding contracts (the infants being physically and mentally incapable of doing so, and the adolescents legally proscribed from doing so), but at all stages they still have natural rights.
As for quantifying the entitlement, that's essentially asking to quantify the sum of human rights, more a subject for a book or a philosophical seminar than an SI post. Although in the case of fetuses most rights would be inoperative and/or fairly meaningless, so you might limit things to the right to live, and not be intentionally harmed.
As for who is picking up the tab, well who picks up the tab for all your other rights? In a direct sense there often is no tab for the rights as such, but there is for protecting them. Your right to life means that someone can't kill you. Someone may forgo a benefit or pay a price if they don't kill you (say your going to inform on them to the police), and there is a cost for any bodyguards you might hire, or for police directly protecting you, or arresting the would be murderers or just generally keeping the peace, but this usually isn't look at as "the tab" for your rights. |
