Why is legal personhood not attributed to the unborn if the unborn are fully human?
The Catholic understanding is that people are fully human from conception to natural death. This is a result of having a soul, reflecting our creation in the image and likeness of God. A soul is not a measurable thing, but entirely spiritual. It cannot be reduced to heart beat, brain function, movement, or any of the other developmental signs that show that an unborn baby is becoming more recognizably human.
Christianity understands that all humans have souls (along with possibly Jews and Muslims), but secularists (e.g., atheists, agnostics) deny the existence of a soul, choosing to interpret “the mind” as an emergent property of biology that does not exist until a child develops and learns. As a result of the Establishment Clause of the Constitution, courts have rejected claims that are rooted in a Christian understanding of human anthropology.
In place of the Catholic understanding, the U.S. (in
Roe v. Wade) uses the concept of “viability” (that is, when a baby can survive outside the womb) as the basis for when (in gestational time) banning of abortion is licit.
Doe v. Bolton expanded this definition as well. Since then, the pro-life movement has, in my eyes, used bad science (e.g., the poorly-supported fetal pain theory) to try to prove the legal personhood of the unborn, and had very little success. Much of the fetal pain emphasis has been on outlawing abortion after 20 weeks. To me, the survival of very early preterm infants provides a better, more empirical basis of “viability,” with significant fractions of infants born from ages 21-23 weeks surviving at least until they leave the hospital.
Is it just that the unborn have not yet separated from their mothers?
The pro-abortion movement has a philosophical argument from Judith Jarvis Thomson that argues that if in the middle of the night while you were asleep, someone conducted surgery on you to save the life of a famous violinist who had been grievously injured in an accident by attaching her blood vessels to yours, so your kidneys can filter her blood and prevent her from dying. Judith Jarvis Thomson argues that since you were never asked whether you wanted to have this violinist hooked up to your kidneys, you are perfectly within your rights to detach yourself from the violinist, even if that means that the violinist dies. For them, this is a slam-dunk argument, because they say that an unintended pregnancy creates the same situation in a woman. Even if the baby is fully human, they argue that the woman has the right do deny the baby the use of her body (the mother’s) for gestation. The gaping hole in this argument is that any voluntary sexual act, with or without artificial contraception, involves some risk of becoming pregnant. The main counter-argument is that having voluntary sex means that you assume responsibility for the consequences of that choice. This argument against the “famous violinist” example points out that, except in the case of rape, a woman always has a choice to avoid pregnancy by not having sex.
If so, does that make sense when the mother and child have different DNA and are different human beings?
Different DNA has no bearing on the legal status of the unborn. While there is no doubt that they are a separate organism from the mother, that is not a sufficient condition for the baby to survive to the point of viability. Also, a drop of your blood has DNA in it, but that doesn’t meant that it has rights (this is a rendition of the “blob of cells” argument). Transplanted tissues and organs have different DNA than the person receiving the transplant. In like fashion, the pro-abortion movement says that the “blob of cells” that is an early conceptus/embryo/fetus is simply a biological “thing” with no mind and therefore no personhood.
