I heard a thoughtful person -- who happens to be pro-choice on abortion -- say the other day that "each person is necessary."
That statement gives us a sense of the special dignity and importance that people have. And we recognize that importance by treating each other a certain way -- for instance, we don't kill people without extremely good justification. Each person is of inestimable worth.
The statement also made me think: What is it that is "necessary"? It's the person. It's me -- who I am -- that is necessary. And when did I come to be? Assuming a continuity of personal identity throughout the life of a human organism, what I am came to be at my conception, when a new physical organism came into existence.
What this means is that I am the same person as the embryo inside my mother's uterus who -- 25 years ago -- grew into a fetus who was then born and became an infant, and then a toddler, a child, a teenager and finally an adult. I am identical to who/what I was at each of the earlier stages of my development.
It follows that if I am "necessary," then the embryo I once was is necessary. So the "embryonic me" ought to be treated with the same kind of basic respect as the "adult me," and this seems to preclude killing the embryonic me by abortion for the reasons people have elective abortions. (After all, no one argues that my adult self may be killed for the reasons people have elective abortions.)
How could that thoughtful pro-choice person escape this conclusion? Either by denying that what is "necessary" is really me (that is, what I am as such is not necessary) or by claiming that I am separate from my body and that my living body can (and does, at least in the prenatal stages) exist without me, thus denying a continuity of personal identity. The latter option is philosophically implausible (subject to devastating criticism; see here and here), and the former seems to empty the statement "each person is necessary" of its powerful and intended meaning.
So I think it's reasonable to conclude that "each person is necessary" must include the unborn, who we should therefore treat with dignity and respect, just like everyone else.
