The word/concept/label “mother” is used in different ways; we said it’s ambiguous, even in ordinary people’s mouths.
The label “person” is also used in different ways; though sometimes the communities that use it in these different ways aren’t “ordinary people.” They’re lawyers and judges, or philosophers or other scholars.
Often, someone will say “person” when they don’t mean anything different than “living human being.” By a “human being” we mean a certain kind of biological organism or animal — nowadays, one whose parents were also human. (Maybe someday genetic engineers will be able to create biological organisms of this kind that don’t have parents.) Sometimes we also talk about dead human beings as persons too: “I know there are many wrecked homes and cars in the flood zone, but did you find any people? If so, were any of them alive?”
As we pointed out in our early class meetings, we can also understand “person” in such a way that “person” isn’t equivalent to “human being.” It makes sense to consider the possibility that members of intelligent alien species would also be persons, or AIs/robots, or even some non-human animals on Earth.
Sometimes people will say that “person” picks out the kind of thing you are, whatever you are. So if you only came into existence sometime after your biological body did, and might go out of existence sometime before your biological body does (perhaps even while it continues living), then the “person” you are didn’t exist for the whole time your body does. If what you are is some kind of non-physical, perhaps immortal soul, then that’s the kind of thing “persons” are. If on the other hand, what you are is your living biological body, then that body counts as a “person” for its entire lifetime.
This way of talking makes sense. But as we’ll see, some people use “person” in other ways, and they might consider and argue about the possibility that you existed before you became a person, or that you will continue to exist after no longer being a person.
In the mouths of lawyers and judges, the term “person” has a specific legal meaning. (This can vary in its specific details between different jurisdictions, but we’ll ignore those differences and just talk about the dominant view.)
This legal sense of “person” goes together with certain legal rights. It’s connected to why the law will treat you differently if you hit me than if you hit my fence. I’m a person and the fence is just a thing. You can face penalties for damaging the fence, but the law doesn’t see the fence itself as being “harmed,” as having rights that you violated. It would instead be the fence’s owner who was harmed, because you damaged their property. The legal notion of a “person” is meant to capture the idea of something that has those special legal rights (and also special legal responsibilities).
Some notes:
The notion of a “person” doesn’t capture the fullest sense of legal rights; there are additional rights that are only given to special classes of persons, for example citizens. Instead “person” is supposed to be a broad inclusive notion, that’s associated with something like a basic “starter set” of rights.
I’ve sometimes heard it said that the law doesn’t count any non-human animals as “persons” — which is true, except for a few controversial court cases outside the US — and that this is because the law doesn’t give them any rights. That is, if the law gives you any rights at all, you count as a person. I am not a lawyer or legal scholar, but from what I can tell from my reading, these latter claims are incorrect. Many legal jurisdictions do give animals some rights — they do count them as having “welfares” and capable of being “harmed,” and say we have some duties to the animals themselves. But they don’t give them all the rights that they give to “persons.” Something similar may also be true for human embryos in a lab. They may have some rights, but not yet be counted as “persons.” So “person” isn’t really the law’s most-inclusive or weakest notion of something that can bear rights.
Although those living biological organisms aren’t counted as persons, there are some entities the law does count as persons that aren’t alive. Entities like Google and the city of Chapel Hill, and in some places rivers and other natural features, are also counted as “persons.” They aren’t given as many rights and responsibilities as human persons are (even the human persons that aren’t citizens). But the law does count them as having the rights and responsibilities that are associated with the label “person.”
What kinds of rights and responsibilities are we talking about? What rights and responsilities does the law associate with animals, with persons in general, and with special classes of persons, like the human ones or the ones that are citizens?
The fourth kind of meaning “person” can have is as a moral notion rather than a legal one. It could mean the kinds of thing that morally ought to have the rights that the law associates with persons — even if the law doesn’t yet acknowledge it. So for example, many animal rights advocates believe that non-human animals are persons in this moral sense, though they’re not yet legal persons, and that’s an injustice. Or you might associate the label “person” not with the same bundle of rights and responsibilities that the law does, but with other rights and responsibilities. Then something would be a person in that moral sense if they had those rights and responsibilities. So there really can be several moral notions of “person,” depending on which bundle of rights and responsibilities you’re talking about.
A fifth kind of meaning “person” can have is in terms of some kind of psychological capacity. There’s really several psychological notions of “person,” depending on which psychological capacity you focus on.
We could expand or refine this list. It’s meant just to give a range of capacities philosophers focus on, not to be definitive. Some philosophical debates concern which of these capacities (either on their own, or in combination with others) make a creature deserve to be counted as a “person” in other senses described above. That is, that they should have some rights, and/or that they have some responsibilities to other creatures. One could also argue that “personhood” goes together with some rights and some of the psychological capacities on this list, whereas other rights and responsibilities go together with other capacities on this list.
The most important questions are which rights and responsibilities should go together with which psychological capacities. It’s a secondary matter which of these combinations we decide to attach the label “person” to. And perhaps there isn’t only one single correct way to make that second decision.