Artificial Intelligence and Personal Identity
Alexander R. Pruss
Could a computer or robot be a person: a being that, at least under normal circumstances, is a thinker and an agent, responsible for its thoughts and actions?
Let me clarify the question a little. Research in Artificial Intelligence is progressing. It is, admittedly, progressing more slowly than was once expected, but it is moving ahead. It seems not unlikely that one day robots will be able to function in ways that will look just like the functioning of a person. If so, we will be able to have what seem to be conversations with them, and get what seem to be the sorts of answers that a person would give. I am not asking in this paper whether this much is possible. I am asking, rather, whether even if we achieved all this, this would be genuine personhood. This question is, I think, tightly bound up with the question whether the robots would be thinking and acting rationally, or whether it would merely appear that they are.
The mere appearance of thinking and acting rationally is not so hard to get. If I can get a good estimate of the sorts of questions someone might ask a computer, I can program the computer to give pre-programmed answers to those questions. You ask what the computer’s name is, and the computer utters the sound: “I am HAL.” If I am good enough at this, maybe I can make people think that the computer is really communicating, is really telling them what it is thinking. But just pre-programming a lot of answers to questions does not give the computer an understanding of the questions and answers.
Even a somewhat more sophisticated program need not have understanding. I can right now put into Google the question “What is seven plus five?” and immediately Google comes back with “seven plus five = twelve.” The engineers at Google programmed their servers to recognize arithmetical expressions in English, and then to compute answers. But there is no understanding on the part of the computer as yet—there is just the non-conscious processing of patterns of characters, with no responsibility or thought.
While it is an interesting technological question whether we can make a robot that externally seems to behave just like a person, passes psychological tests and so on, the philosophical question is whether we could make such a robot that would be a person, and not just seem to be a person. Or would it just be non-consciously processing patterns, with no responsibility or thought?
I will approach this question through considerations of personal identity. We can ask various questions about the identity of persons, for instance across times. We can ask whether this person here and now is the same as that being there and then. There was a certain five-year-old who grew up to be me. Was that five-year-old the same person as I am? I think the answer is clearly “Yes.” On the other hand, there was a once a person named Queen Victoria, and now there is a corpse at Frogmore, Windsor. Is Queen Victoria the same person as the corpse? No: for the corpse is not a person at all. (So strictly speaking it is not correct to say that Victoria is buried at Frogmore—only her corpse is.) If you have a pair of Siamese twins, is that one person or two? Surely two—each is a person, and each is a distinct person. These questions are easy to answer.
But if I erased your memory completely, and then tortured the resulting amnesiac, would you be the one feeling the pain, or would the pain be someone else’s? Unlike the questions about the five-year-old in my past, Queen Victoria and Siamese twins, the answers to this question are controversial. Some maintain that your identity is guaranteed by the persistence of your body or maybe your brain, and so the amnesiac would be you, and hence the pain would be yours. Some hold that your identity is guaranteed by a stream of memories, in which case it wouldn’t be you who is tortured after the amnesia, and so while it makes sense to feel sorry for the person being tortured, there is no need to have a first person fear of the pain, because you will no longer exist after the amnesia. And, finally, some hold that your identity is guaranteed by the presence of something over and beyond the body, a soul. If so, then answering the question is difficult, for we would have to know whether the soul remains in the body after amnesia. I incline towards the soul view, and believe that the soul remains in the body as long as there is life, even if there is amnesia. If so, then you do have reason to fear the pain ahead.
We may not know what the answers to personal identity questions are. But it is, I submit, a part of the concept of a person that there exist answers to such questions, though perhaps the answers beyond our knowledge. It is crucial that either it be true or be is false that x who is a person is the same being as y. The notion of responsibility presupposes identity: you are only responsible in the relevant first-person way for having thought or done something if you are the being who thought or did it.
All my arguments will have the form of a reductio ad absurdum: I assume that computers or robots can be persons, and then I argue that some considerations connected with personal identity probably lead to absurdity. Consequently, I conclude that the assumption that computers or robots can be persons is false. The basic theme is that I will ask a question related to personal identity, assuming computers or robots can be persons (I will not distinguish computers from robots for the purposes of this paper), and argue that the question probably cannot be answered in the case of robotic persons. Since the question is one that would have an answer if robots were genuine persons, it follows that robots are probably not genuine persons.
Suppose Robby is a robotic person, and I turn Robby off. Is Robby still in existence when turned off? In other words, is Robby the same person as the turned-off robot. I will argue that the answer is both yes and no. Since the answer cannot be both yes and no, we must reject the presupposition in the question that it is possible to have a robotic person.
So, first let me argue that Robby is still in existence when turned off.
Argument A1a: Robby is an artifact like a vacuum cleaner or car. These artifacts certainly continue to exist when turned off, and hence so does Robby.
Note: This argument, plausible as it may seem, will not convince everyone. One might think that the essential component of Robby is the software, and in this way he is different from artifacts like vacuum cleaners or cars (though as vacuum cleaners and cars get more sophisticated, this objection becomes weaker). In particular, Argument A1a will not convince those who have a subtler view of the connection between Robby the robotic person and the physical artifact than just saying Robby is the physical artifact. One might instead say that Robby is constituted by the artifact, and is somehow to be identified with the functioning of the software running on the artifact. If one turns off Robby, the software no longer runs, and so Robby ceases to exist.
Argument A1b: To be a person, one does not have to be actually thinking and acting. Otherwise, we would cease to be persons while in deep sleep. All one needs is a capacity—according to some philosophers any capacity and according to others a well-developed capacity—for thinking and acting. But Robby when he’s turned off surely has a well-developed capacity for thinking and acting. He just can’t exercise this capacity until one turns him on. Being turned off is like being asleep, rather than non-existence.
Argument A1c: Some people think it is impossible to exist, then not exist, and then to exist once again. If this is correct, then Robby is still in existence when turned off, since it is clear that he exists before being turned off and then after he is once again turned on.
Note: One reason many people will reject this argument is that if you give your watch to be repaired, the watch may be taken into pieces. When it is taken into pieces, the watch doesn’t exist—only its parts do. But then when the pieces are put back together, you have the same old watch back again. So having a temporal gap in one’s existence is quite possible according to these thinkers.
Argument A1d: To conserve energy, a computer may turn itself off until a timer goes off or sensor is activated, which will then turn the computer back on at a later time when it is needed. (“Standby mode” is something like that.) Suppose Robby turns himself off for a second in this way, with a timer turning it back on a second later. It seems very plausible to say that Robby is in existence during that second. But suppose that instead of an internal timer, there is an alarm clock attached to Robby’s outside with rubber bands, in such a way that when Robby’s switch is flipped to off, the alarm clock is set to go off in an hour, and when the alarm clock goes off in an hour, it flips Robby’s switch to on. Surely the fact that the timer is physically on the outside rather than inside doesn’t matter.
Perhaps, though it matters whether the timer is external or internal in this way. Perhaps the external timer is not really a part of the robot. But it would be strange if something attached with rubber bands wasn’t a part of the robot, whereas something welded to it would be. So this way out doesn’t work. The externality of the timer doesn’t matter, and so Robby continues to exist even while turned off by the alarm clock, just as he would even were he turned off by an internal timer.
But suppose that while Robby is turned off, I detach the alarm clock, and bring it back half an hour later. Have I really made Robby cease to exist for that half hour by detaching the alarm clock? And anyway, why does it matter what turns Robby back on, whether it is the alarm clock by itself, or me plus the alarm clock (as when I take the clock away and bring it back), or just me by myself? It seems that either in all of these cases Robby is existent when turned off, or in none of them is he existent when turned off. Since in the case where the alarm clock is securely attached, Robby is still in existence while turned off, he is in existence while turned off in all of these cases. Hence, he is in existence when I turn him off with the intention of turning him back on.
While there are objections available to some of these arguments, I think there is a very strong case for a yes answer to the question whether Robby exists while turned off.
But there is also a very strong case for a no answer.
Argument A2a: Robby, on our assumptions, is a person without a soul. (We might suppose that a soul pops into existence when Robby is assembled, but how likely is that view?) Only a person with a soul can exist while not alive (and even that possibility is controversial). But Robby is not alive when he is turned off: Life requires active functioning. If Robby, then, is like we would be if we were persons without souls, then Robby does not exist when he is turned off.
Argument A2b: Let’s think a bit about what it could physically mean to “turn off” Robby. One way to do this would be to press a switch that disconnects the electrical connection between the battery and the rest of the robot. But it seems to me that the answer to the question whether Robby would continue to exist when turned off should not depend on exactly how turning him off works. My son has a battery-powered toy car where the switch works by physically pushing the battery away from its connector. We could imagine that Robby’s off switch works by pushing the battery out of him. But the battery is, surely, a crucial part of Robby. Without such a crucial part, Robby does not exist, just as we would not exist without a heart unless we have souls. So if turning him off works by pushing out a battery, he doesn’t exist when turned off. But it shouldn’t matter exactly how we turn him off, and hence no matter how we turn him off, he doesn’t exist when turned off.
Maybe, though, Robby’s memories survive while he is turned off, because they are recorded on a kind of memory that does not need electricity. Could we say that Robby, then, survives while turned off, even though he is lacking a crucial part? No. Our memories are presumably recorded in our brains, but we’re dead as soon as we stop functioning, even though, quite likely, for a few minutes—or maybe longer—our memories could still be recovered from traces in our brains, if only we had the technology for it. That a record of memories exists does not mean that life continues, and similarly that a record of memories exists does not mean that Robby continues to exist.
But suppose you’re not convinced by this. Suppose you think that as long a record of memories exists, then Robby continues to exist. Well, then, imagine a different thought experiment: All of Robby’s memories are printed out, on a very long piece of paper in small type. Then the electronic copy of the memories is destroyed while Robby is turned off. When we turn him back on, the memories are typed in again from the piece of paper, maybe by a human typist, maybe by a trained monkey, or maybe by an electronic scanner that reads the piece of paper. Then, a record of Robby’s memories does continue to exist while he is turned off and his battery is removed. It seems clear that in this case, Robby doesn’t exist when his battery is removed, despite the printed record of his memories existing. But there should be no metaphysical difference between a printed record and a record on a disk, so neither does he exist in the case where the memories are held on a disk.
Maybe, though, you think removing the battery is not enough to make Robby cease to exist. Well, remove more parts, one by one. Eventually, Robby doesn’t exist—there is just a desk full of parts. But at which point does he cease to exist? There is no sharp line once the battery is removed. The removal of the battery is a fairly sharp line—once the battery is gone, Robby doesn’t function, doesn’t in any sense live. But after the battery is removed, there are no more such sharp lines. Since the cessation of existence is a sharp line, removal of the battery is what makes Robby cease to exist.
So, we have a strong case for a yes and a strong case for a no. We could decide on a yes. But then the no arguments would be against us. Or we could decide on a no. But then the yes arguments would be against us. The right decision is to reject the supposition that the question was based on, namely the supposition that there can be a robotic person.
In the case of a robot, the answer to the question whether the robot is still existing when turned off is one to be given by social convention, not by the objective fact. In the case of a person, the question whether the person is still existing at a given time is a matter of objective fact (though perhaps in some cases, such as those of brain death, this fact is hard to determine). Therefore, robots are not persons.
When we’re dealing with persons, the question “How many different persons are here?” should make sense for appropriate senses of “here” (“here” need not be physical—it could indicate a context instead).
There are two basic ways to try to answer this question for electronic persons. The first is to correlate persons with pieces of computing hardware. Some of the arguments in the previous section were based on that kind of a view. On a hardware-based view, if there are three intelligent computers, then we have three persons, even if one of these computers is multitasking several intelligent programs, each communicating with a different user through its own window. A second way would be to focus on software, and to correlate persons not with pieces of computing hardware, but with streams of computation. Thus, a single computer could be “inhabited” by a dozen intelligent persons, each constituted by a separately running process. I shall argue that neither approach succeed in giving satisfactory answer to the “How many” question.
On the hardware approach, a difficult question is how to count pieces of computing hardware. For instance, I am writing this paper on a laptop with a dual core processor. Is this one piece of computing hardware or two? A dual core processor is, basically, two processors in a single package. While one of the processors may be processing my typing, the other may be checking for viruses. Yet to the ordinary user the laptop behaves like a single computer, and Microsoft treats it as such (you only need to buy one Windows license for it).
To some degree, our two-hemisphere brain may function like a dual core processor. But surely the brain is a single piece of computation machinery—we are not actually two persons (leaving aside cases of split brain patients). So if we’re counting electronic persons by counting pieces of machinery, we should count my laptop as a single piece of computing machinery.
But how does one, then, distinguish between a single laptop with two processors and two laptops with one processor each? The physical condition that to have two laptops they would be in separate plastic cases is clearly not right. If I took the insides of the two laptops and placed them in a single box, they would still be two laptops—even if I glued them together! (Siamese twins are two persons.) Nor can I say that I have one laptop whenever there is only one keyboard and only one screen. After all, it’s easy to hook up a second screen and a second keyboard.
Such physical criteria are, surely, beside the point. If anything makes the laptop a single computer, it is that it’s functioning as a whole. There may be two processors, but they are working together, in a well-coordinated way. But this coordination is a matter of software, not hardware. I could, after all, connect two computers to the Internet, and running the right software on both, operate them as a cluster that functions as a single, larger computer. So it is not some kind of physical interconnectedness that makes my laptop be a single piece of computing machinery.
If we employ hardware-based criteria for counting electronic persons, we will get things wrong. And, besides, there are no precise distinctions we can make between “one computer” and “two computers”.
The question “How many computers are here?” is not answerable in general, I think. Do we count two laptops glued together as a single, more complex computer, or do we count them as two individual computers? The same problem comes up for other kinds of artifacts. Suppose I take three chairs and tie them together, side-by-side. Do I have a single, new piece of furniture—a bench with 12 legs—or do I still have three pieces of furniture?
In fact, I think it objectively does not matter what we say. The answer is just a matter of social convention. There is no objective fact to be discovered by metaphysical investigation of the chairs or laptops. It is simply up to us to decide whether we count a set of three chairs tied together as one piece of furniture or three (or maybe even four). Of course, the answer may matter, say, for legal purposes. If I have an insurance policy that covers only one computer, and then the two laptops glued together are destroyed, then there will be a legal question whether I can claim the total loss or only half of it. But the answer is one to be determined by the courts, or by linguistic convention, rather than by objective facts.
But this is not so for persons. The question of how many persons there are, whether here there are two persons or one person, has an objective answer, though sometimes we may not be able to find that objective answer. Therefore, if the hardware approach to counting electronic persons is right, then robots can’t be persons. For if they were persons, there would be objective answers to the question of how many of them there are. But there are no objective answers available for such questions about electronic persons, at least on the hardware approach.
The software approach is more promising. If I run one intelligent program on one processor core and another on another core, I have two electronic persons, but likewise if I run them both on one core, I still have two electronic persons. If, on the other hand, I run a single intelligent program in parallel fashion on several processors, indeed on several computers, each computer doing its part of the total computation task, then I have only one person, spanning multiple computers. This approach is promising as it embodies the conviction of those who believe in the possibility of Artificial Intelligence that it is not the physical substrate that matters for personhood, but what matters is the computation that is going on.
However, the software approach to counting persons also runs into difficulties. One of these is that if it is applied to us, it may mean that a human being with multiple personalities is literally more than one person—there is more than one stream of computation going on there. Maybe, though, you do not think that is absurd, or maybe you think the approach cannot be applied to us, but only to electronic persons.
A second difficulty is that it is sometimes difficult to count streams of computation. Suppose that I want to compute the positions of the planets in 10,000 years. But I want to be really sure of the result. So I take eleven computers with the same hardware specifications. One of these computers, then, sends to each of the other ten the task to compute the positions of the planets in 10,000 years using the laws of physics and the present positions, giving each computer the same program to run. The coordinating computer then checks to make sure that the memory state of each of the ten computers is, at each time, exactly the same. As soon as the memory state of one of the ten computers deviates from the others, the coordinating computer modifies the deviant to match the others. (If more than one deviates at the same time, the coordinating computer goes crazy and explodes everything, maybe, or maybe conforms the minority to the majority if possible.)
Should I see this situation as consisting of ten streams of computation of the positions of the planets? Or maybe eleven (ten individual ones plus the whole consisting of the coordinator plus the ten subsidiaries)? But the ten streams of computation are highly dependent on one another. The coordinating computer ensures that as soon as any deviation occurs, the coordinating computer cancels out the deviation. If it is interdependence that defines a single stream of computation, then I think the right thing to say in this case is that there is only one stream of computation.
Now let us imagine a version of this hypothesis for intelligent programs (it doesn’t take intelligence to compute the positions of the planets, just a lot of hard work with an abacus). We have ten intelligent computers, that is ten computers running an intelligent program. And we have an eleventh computer—this one isn’t intelligent since its task is simple—which gives them all the same input, and monitors their functioning. As soon as any of the ten were to diverge from the others, it would get pushed back to the same state as the others. But let us suppose that in fact there is no divergence. Here, I think, we can make a good case for the hypothesis that we have ten intelligent programs, each running on one computer, as well as for the hypothesis that we have one intelligent program, running on a system consisting of eleven computers.
First let me argue that we have ten intelligent programs. Let us suppose that in fact none of the ten computers diverges from the others—no malfunctions occur. The fact that they are always thinking the same thing does not make them be one person. After all, it is quite possible, though unlikely, for two people to be always thinking the same thing—imagine you and an identical twin on a planet just like ours, where everything is just like here. Why should the existence of a coordinating computer make them all be one person, if the coordinating computer does not actually do anything to them—it just watches for deviations, but if there are no deviations, as on our present hypothesis there are not, it does nothing. Suppose you have two identical triplets who always think the same thoughts. If Big Brother watches the three of you, and will force the thoughts of each to conform to the thoughts of the majority whenever there is divergence (and blow up all of you if there is no majority), that does not make the triplets into a single individual, at least if you always happen to agree with one another by chance.
On the other hand, it seems clear that overall we have a single computational system, made up of eleven sub-parts. This single computation system is running an intelligent program with the additional feature that the intelligent program is resistant to hardware failure (since deviations get canceled out).
Perhaps, then, the right way to look at this is to say that we have eleven persons. One is the system as a whole (running on an aggregate of eleven computers), and then there are the ten component persons (the coordinating computer does not count as a person, because it isn’t intelligent—it just automatically cancels out deviations in functioning). So we have one person who has ten more persons as parts. That isn’t of itself absurd, perhaps. (Or is it? Maybe it would imply that each of us is a person who has two persons—one per hemisphere—as parts?)
But what does seem absurd is that just by inserting a coordinator who in fact does nothing (because nothing is to be done), one has created a new person. Suppose that you and your two identical triplets are going along thinking the same thoughts. And then a non-intelligent computer is put into place, whose job is to ensure that your and your triplets thoughts never diverge. As soon as the thoughts diverge, the computer will make them converge again. But in fact, your thoughts do not ever diverge. So in fact the computer doesn’t affect anything. Yet, a fourth person is thereby created if we accept the view above that there are eleven persons in the computer case. This seems absurd.
Moreover, I perhaps don’t even need a coordinating computer to get the problematic result. Let’s take ten computers, and run different copies of the same intelligent program on each, and give each the same input. We can think of the ten computers as together running a single program in a more reliable way simply by treating them as a unit—once the output comes, we simply accept the majority output (typically the outputs will be the same). But does how we think of a bunch of persons affect how many persons there are? Surely not.
I think that on the software view, it is also true that the question of how many programs are running is answered by our subjective decision as to how we want to consider a situation: do we want to think of it as a system running one program, or several systems running several copies of a program, or maybe in some other way. Again, I doubt that there would be an objective answer to the question of how many intelligent programs there are. But if not, then programs are not persons, since there is an objective answer to “how many” questions in regard to persons.
Still, the software view seems to work better than the hardware view. So for the next identity question, I will only consider the software view.
I can take a piece of software running on one computer, record all the computer’s memory to disk, erase the memory, put the disk in another computer, restore the data from disk to the memory of that computer, and continue running the software there. On a software view of the nature of electronic persons, if the software constitutes a person, the person should survive such transfer—after all, the stream of computation continues.
One question to ask is whether the alleged electronic person exists when the software is not running and all we have is a memory record on the disk. We asked this question when we considered whether Robby existed while turned off. I do think this question leads to problems for the proponent of the possibility of electronic persons. For it is absurd to suppose that an inert disk, or even the information on it, could be a person. On the other hand, how does the case where the data is temporarily on a disk actually differ that significantly from the ordinary running of a computer program? After all, when a program is running, sometimes the computer just keeps it stored inertly in memory while doing something else. So if the disk or the data on it is not a person, neither do electronic persons exist except just when the computer is doing something with the programs that constitute them. But if so, then by parallel, it seems that should my mental activity pause for a moment, I would not exist then, which seems false.
But I want to focus on a different, and very standard in the theory of personal identity, set of questions. Call the electronic person I had before the memory recording “Robby”. Suppose that I actually make two copies of the memory record, and then simultaneously put them into two computers. Where does Robby go? Does Robby inhabit both computers now? But that seems absurd. After all, the two computers might now be given different inputs, and thus might be doing different things at the same time. Does the program as running on one of the computers need to be afraid if the program as running on the other computer is facing pain (after all, if computers could be intelligent, they could suffer pain)? Surely not.
Or does Robby inhabit only one of the computers? But which one? After all, the data was put into both simultaneously? Again, there does not seem to be an answer to this question.
Or, perhaps, Robby inhabits no computer after his data has been sent to two computers. But then it follows that if Robby’s data is restored on only one computer, Robby continues to exist, but if it is restored on two, Robby ceases to exist. This, too, seems very strange. Let’s suppose that when Robby’s data is put on a disk, a copy of the disk is carried in a spaceship to a far away star. Why should it affect the question whether Robby exists on earth what is done with the copy of the disk on the spaceship? Yet, if on the spaceship the data is restored at the same time as the one on earth, then Robby ceases to exist on this hypothesis, but if only the disk that is on earth is restored, then Robby continues to exist on earth.
So there is no good answer to the question whether and where Robby continues to exist in this thought experiment. But in any real situation, when dealing with persons, there has to be an objective fact whether the person continues to exist or not.
But there is a serious weakness in all of the above arguments. In these arguments, I suggested that certain questions about personal identity have no answers in the case of electronic persons. But there are exactly parallel questions that we can ask about human persons.
Parallel to the question whether Robby continues to exist when he is turned off, we can ask whether people continue to exist while in a coma. Parallel to the question of how many electronic persons there are, we can ask how many humans there are—think of Siamese twins, for instance, as a way of making this question problematic. And parallel to the question whether Robby’s data is restored on two computers, we can imagine fanciful thought experiments where my brain is split in half, and the two halves are put in different bodies—where, if anywhere, would I be then?
I suggested that in the case of electronic persons these questions cannot be answered. But then how can they be answered in the case of humans? Here I need to note a hidden assumption in my previous arguments. I was assuming that there was nothing to electronic persons but the hardware and the software or data, that there was no further metaphysical reality beyond these. Thus if we were going to come up with an answer whether Robby continues to exist while asleep, this answer would have to depend only on the hardware and the software—there is nothing else there. And the hardware and the software fail to give an answer to the question.
But exactly the same point can be made about humans. If all there is to us is a bunch of molecules and a bunch of data encoded in these molecules, then questions of personal identity do not always have objective answers. If these questions are to have objective answers, there must be more to us than just molecules and data. What could be this “more” that makes answers possible? It has a traditional name: “soul.”
But even supposing a soul, we do not know what the answer is for some of these questions. If my brain is split in half, where do I go? Well, if I have a soul, then I can say that the question is ill-defined. “What if” questions only make sense if sufficient information is specified. The question: “What if you moved one third of the human beings from this room to another room, which room would I be in?” has no answer because sufficient information is not specified. One needs to know whether I would be among the one-third moved or the two-thirds remaining to answer the question. Likewise, the question: “If my brain is split in half, where do I go?” has no answer unless one further specifies which half of the brain my soul goes with or maybe that my soul goes with none. I will go where my soul will go. (This is basically Richard Swinburne’s argument for the existence of a soul: only if we have souls can there be answers to certain questions.)
However, in the case of an electronic person, when we describe what happens to the hardware and the software, we are in some sense describing everything relevant, and so we should be able to get answers. Assuming electronic persons don’t have anything beyond the hardware and the software, the question is sufficiently specified once we’ve given the facts about what happens to the hardware and the software, such as in my example where Robby’s data is recorded in a disk and restored on two computers. And yet, even though the question is sufficiently specified, there is no answer.
If this is right, then computers and robots cannot constitute persons unless, somehow, there is more to them than hardware and software, namely unless computers and robots will have souls. But that would seem improbable.
 Interestingly, the question of the permissibility of abortion may turn on this distinction. Thus, Mary Anne Warren has claimed that personhood requires a developed capacity for rationality, which fetuses lack, and hence fetuses are not persons. Some others, however, think that simply having the capacity for rationality, developed or not, is sufficient for personhood. If so, then fetuses are persons, since they plainly have an undeveloped capacity for rationality.