Defining a "Person"

The Supreme Court's most recent allowing restrictions on late-term abortions has once again raised the painful question of what rights, if any, does a fetus have. Opponents of abortion set a bright, clear and offer a bright, clear reason for it. Life (and, by extension, full rights of personhood) begins at conception because from the very moment of conception each of us has a unique genetic endowment that remains unchanged for our entire lives. Opponents of abortion are extremely vague as to what rights, if any, a fetus has and when, if at any time before birth, they begin to vest. But if one is going to deny that genetic uniqueness defines personhood and all its rights, one does well to explain why not, and what does define a person. Birth seems a poor answer, since a full term fetus inside its mother is really no different from a newborn. Viability is no better; it suggests that incubators and the state of neonatal medicine can determine when personhood begins.

A better place to begin is to consider what is wrong with defining personhood as genetic uniqueness. The answer is obvious -- identical twins. Identical twins are genetically the same, yet different people. And what makes them different? Separate bodies? No, because some twins are born conjoined, yet they are still separate people, with their own separate personalities and separate tastes. So if conjoined twins are genetically identical and share much of the same body, what makes them separate people? Surely it is because each has a separate functioning brain. And reinforcing this hypothesis consider separation. It is the accepted practice to separate conjoined twins if there is a reasonable likelihood that both will survive. But if they share so many organs that it is impossible for both to survive, it is not acceptable to "discard" one twin to save the other. But imagine as a hypothetical (I do not know if it is possible) one head but a split below the waist. Presumably no one would object to amputating a duplicate set of legs or even internal organs, even though, of course, the amputated organs are living tissue that would die if removed. But without a brain, duplicate organs have not claim to personhood.

Defining personhood by functioning brain rather than genetic uniqueness also works at the end of life. Death is defined as the cessation of brain activity. Yet if the person who dies is an organ donor, any number of living organs with his or her unique genetic code may survive in someone else's body. Yet no one would regard the donated organs as a separate "person" from the donee because they are genetically different. And once brain function ceases, the donor is no longer an existing person, no matter how many other living organs have his or her genes.

So, if a functioning brain defines one's status as a person over one's lifetime and at the end of one's life, it makes sense for brain function to define personhood at the beginning of life as well. Let an embryo be recognized as a person when it begins to have a functioning brain.