Why do we have trouble defining what a "person" is? The answer may lie in human evolutionary antiquity.
Recent efforts by radical pro-life conservatives to establish a definition of personhood that specifically includes the embryo at the moment of conception have failed both in at least three ways. First, they have been rejected by voters in Colorado (twice) and Mississippi. Second, they have failed to win the hearts and minds of most cultural conservatives themselves, with even respected leaders like outgoing Mississippi Governor Haley Barbour withholding an enthusiastic endorsement. Third, moderate voters worried about the implications for contraception and fertility treatments. The Mississippi initiative defined a person as "every human being from the moment of fertilization, cloning, or the functional equivalent thereof."
The ambiguous language of "humans", "human beings" and "persons" is too rarely noticed as a key factor in the ways that people talk past each other. Progressives might blanch at the intuitive implications of calling a human embryo a human being, but (as a leading conservative intellectual pointed out to me years ago), it is surely not a non-human being. Conversely, conservatives worry about the arbitrariness of "person" or "personhood" that could result in dehumanizing those with impaired cognition (like Terri Schiavo), or those who don't measure up based on some racial or other social prejudice, or of course embryos. For them the term might also be too inclusive, as it might apply to our higher primate relatives or perhaps someday to super-intelligent machines with self-awareness.
Is the idea of personhood like pornography? Do we know it when we see it? As the neuroscientists Martha Farah and Andrea Heberlein put it in a 2007 paper, "personhood is a concept that everyone feels they understand but no one can satisfactorily define."
Farah and Heberlein note that there is evidence our brains are "hard-wired" to distinguish between persons and non-persons. They cite a rare condition called prosopagnosia. People with this disorder cannot recognize a human face, yet some of them can still recognize an animal face. Brain imaging has even given evidence that there is a specific brain region, called the fusiform gyrus, for human face recognition. Other experiments show that the sight of human bodies themselves, even with the faces obscured, is associated with the activation of the fusiform gyrus and another brain region. Another brain area is active when actions are perceived to be intentional and still another when we just think about someone else's mental state; in other words, when we think about someone else thinking.
So it seems evolution has set us up to see the world as divided between persons and non-persons. But here's the problem: we evolved in a world in which we rarely encountered ambiguous cases. As Farah and Heberlein wrote in 2007, during 200,000 years of hunting and gathering, "Sonograms did not show us our fetuses; people did not live long enough to develop Alzheimer's disease, and vegetative states were fatal. " They continue:
It is interesting that infants and young children may be the one class of ambiguous cases that our ancestors did encounter on a regular basis, and for these cases it would be adaptive to attribute personhood even in the absence of intelligence and self-awareness. Protohumans who accurately judged their offspring to be lacking in the various traits associated with personhood and accordingly treated them as non-persons would not have many surviving descendents!
It seems that the neuroscientific and evolutionary evidence for a hard-wired but increasingly dysfunctional idea of personhood is compelling (and of course one can accept the neuroscience data without accepting the evolutionary explanation).
In The Body Politic I argue that this kind of disconcerting boundary-erasure is one of the reasons that the new biology, including neuroscience, has stimulated a new biopolitical era. The advocacy group Personhood USA is not giving up, with efforts like the failed Colorado and Mississippi ongoing in other states. And presidential candidate Newt Gingrich has reportedly advocated a federal law that would define a person as present at conception. Although Personhood USA blames Planned Parenthood and the radical left for its defeats, the fact is that the vast majority of voters in a culturally conservative Southern state rejected their campaign.
The possibility that people are giving the matter deeper thought than simply following a convenient ideological line is encouraging. The problem of personhood is even deeper than gaining agreement about the beginning of life. The challenge it presents is the beginning of wisdom, one for which evolution has, we may hope, also prepared us.