Photo by Chad Cooper, via Flickr
Photo by Chad Cooper, via Flickr
ScienceOnly Human

Personhood Week: Why We’re So Obsessed with Persons

It’s Personhood Week here on Only Human. To recap the week: Monday’s post was about conception, and Tuesday’s about the age of majority. Wednesday’s tackled DNA and dead bodies, and yesterday I took yet another opportunity to opine about the glories of pet-keeping. Today’s installment asks why we’re so fixated on pinning down the squishy notion of personhood.

I’d love to hear about how you guys define personhood, and why. Feel free to leave comments on these posts, or jump in to the #whatisaperson conversation on Twitter.


People have been trying to define personhood for a long time, maybe since the beginning of people. The first recorded attempt came from Boethius, a philosopher from 6th-Century Rome, who said a person was “an individual substance of rational nature.” Fast-forward a thousand years and Locke says it’s about rationality, self-awareness, and memory. Kant adds that humans have “dignity,” an intrinsic ability to freely choose. In 1978, Daniel Dennett says it’s intelligence, self-awareness, language, and being “conscious in some special way” that other animals aren’t. The next year Joseph Fletcher lays out 15 criteria (!), including a sense of futurity, concern for others, curiosity, and even IQ.

“Personhood is a concept that everyone feels they understand but no one can satisfactorily define,” wrote Martha Farah and Andrea Heberlein in a fascinating 2007 commentary for The American Journal of Bioethics. Farah and Heberlein are neuroscientists, and they note that neuroscientific tools may be useful for investigating some of the psychological concepts — reason, self-awareness, memory, intelligence, emotion — historically associated with personhood. But even if we had complete neurological understanding of these skills, they say, it would be no easier to define what a person is and isn’t.

But neuroscience does have something interesting to contribute to this discussion: a provocative explanation for our perennial obsession with personhood. “Perhaps this intuition does not come from our experiences with persons and non-persons in the world, and thus does not reflect the nature of the world,” Farah and Heberlein write. “Perhaps it is innate and structures our experience of the world from the outset.” In other words, maybe we’re born with the notion of personhood — and thus find it everywhere we look.

As evidence of this idea Farah and Heberlein turn to study of the so-called “social brain,” regions of the brain that help us navigate life in our very social world.

Take faces. We know that certain brain circuits are responsible for recognizing faces because in some people those structures don’t work properly: People with a condition known as prosopagnosia have no trouble distinguishing between complex objects, and yet they can’t tell one face from another. And some people have the opposite problem: They can’t tell objects apart but have no trouble recognizing faces. Almost 20 years ago, scientists discovered a region of the brain, called the fusiform face area, that is selectively activated when we look at faces.

Farah and Heberlein go on to list many other brain areas tied to people-identification. Looking at bodies (but not faces) activates another part of the fusiform gyrus, and watching body movement (made up only of points of light, and not actual body parts) activates the superior temporal sulcus. The  temporal parietal junction, meanwhile, seems to process the theory of mind, our ability to think about what other people are thinking.

The neuroscientists argue that this network of people-related regions has “a surprising level of automaticity,” meaning that it’s activated regardless of whether we’re consciously thinking about people. Social brain areas are activated not only when we look at realistic photographs of faces or bodies, but when we look at smiley faces or stick figures. Some of us might see a man in the gray craters of the moon, or the face of the Virgin Mary in the burned folds of a grilled cheese sandwich. We automatically assign agency to things as well. In one famous experiment from the 1940s, researchers created a simple animation of two triangles and a circle; watching it, you can’t help but think that the larger triangle is bullying the poor circle:

The social brain also has “a high degree of innateness,” the scientists write, meaning that it’s switched on even in newborns, who have obviously had scant real-world experience with people. A study in 1991 found, for example, that babies just 30 minutes old are more likely to look at face-like shapes that other kinds. (You can see those shapes for yourself in this piece about illusions I wrote for Nautilus.) Some research on autism, a strongly genetic condition, also bolsters the idea of the innateness of the social brain. Many people with autism prefer to interact with objects rather than people, and have difficulty processing facial expressions. People with autism also show differences in activity in the “social brain” regions mentioned above.

At the end of their commentary, Farah and Heberlein make an interesting distinction between persons and plants. Science, they say, offers an objective definition of plants: they are organisms that get their energy through photosynthesis. But science has found no such criteria for personhood. Why? “We suggest that this is because the category ‘plant’ has a kind of objective reality that the category ‘person’ does not,” they write.

Let’s assume for a moment that these neuroscientists are right — that the distinction between persons and non-persons is not something that exists in the world outside of our minds. Does that mean I’ve just wasted a week going on and on about this illusion?

Here’s why I think the personhood notion so valuable. We are people. Our people-centric minds evolved for a reason (namely, our species depends on social interactions) and our people-centric minds dictate how our society works. So maybe personhood is not based in reality. It’s the crux of our reality.