In everyday speech, the term ‘person’ often means roughly the same thing as ‘human,’ which in turn refers to someone who belongs to the species Homo sapiens. However, in practical ethics and in philosophy more broadly, the term ‘person’ has a much more rich, and more complicated, history. In the West, philosophers have often used the term ‘person’ to denote a set of capacities that imply both (A) the ability to engage in certain sophisticated behaviors and (B) an elevated moral standing deserving of certain protections. Personhood in the philosophical sense has been suggested to be related to as diverse a group of characteristics as the ability to remember the past and plan for the future, a sense of self, a narrative conception of one’s life, the use of a natural language, participation in a moral community, and many other suggestions too numerous to list here. And ‘being a person’ is often thought to imply that one is due strong moral protections. Some authors have suggested that personhood is the criterion required to have any moral standing at all, and others have claimed that persons have rights that go above and beyond the moral considerations that are due to “merely sentient” beings who are not persons.

As such, in philosophical lingo, “being human” generally is no longer considered a necessary nor a sufficient condition for being a person. Frodo Baggins or Wonder Woman, for example, would seem to possess the same rights and responsibilities as most humans regardless of how closely their DNA aligns with our own. Hopefully no one would think that it’s permissible to cause harm to hobbits or Amazonians made out of clay simply because they are not technically Homo sapiens! And it’s not just a physical resemblance to humans that matters; ET and Neytiri from Avatar would be persons on any respectable philosophical definition. Conversely, and perhaps more controversially, on some philosophers’ definitions of personhood, there may also be some humans who are not persons. If you held that a narrative conception of self is a requirement for being a person, for example, then many humans (including young children) would not fit the bill.

So if you ask a philosopher, “is a chimpanzee a person?”, you might expect to get the familiar (and possibly slightly annoying) answer, “well, that depends on what you mean by person.” And the philosopher might further be tempted to introduce new terminology, such as “sentient nonpersons” or “near persons” that would allow for a more precise way of dividing up different categories than simply dividing the world into “persons” and “nonpersons.” After all, it certainly would be a mistake to start a discussion about morality with an assumption that those are the only two possible morally relevant categories.

Unfortunately, however, when it comes to legal rights, the current debate about personhood does not allow for the type of free-ranging search for definitions, subcategories, and nuance that many philosophers would prefer in being asked to define ‘personhood.’ The law in the U.S. and many other countries divides the world into two categories: “persons” and “things.” Persons have legal rights. Things have none. The is part of the explanation for the much-maligned notion of “corporate personhood” in the United States…essentially judges decided that personhood status was required to provide corporations with certain legal protections. Right now, all animals are treated as “things” by U.S. law and as such have no legal rights. In many places, if someone accidentally kills your companion animal, that is the legal equivalent of them accidentally breaking your lamp (though there are, of course, certain laws banning types of animal cruelty).

It is against this background that a recent motion was filed in New York State arguing that two chimpanzees, Tommy and Kiko, should be released from captivity into a protective sanctuary based on the common law writ of habeas corpus. Habeas corpus rights only apply to persons. Though I played only an extremely minor role and have my own somewhat orthogonal views that I hope to spell out on this blog at a later date, I was very proud to be part of a group of 17 philosophers who submitted an amicus brief to the court offering our support for the claim that Tommy and Kiko should be regarded as legal persons. Given what we know about the remarkable intelligence and rich emotional lives of chimpanzees, it seems clear that in choosing between saying they are “things” vs “persons,” the correct legal characterization is persons. Or so we argued! I encourage people to read the full brief and consider the argument themselves (but feel free to comment here).

And for more analysis on the topic, please see this post by Andrew Fenton and L. Syd Johnson, two people (among many) who did excellent work on the amicus brief.

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Adam Shriver is a Research Fellow at the Oxford Uehiro Centre for Practical Ethics and the Wellcome Centre for Ethics and Humanities.

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