What do identical twins have to do with Oklahoma's Personhood Bill?

A lot, actually. The process of twinning may pose one of the clearest grounds for challenging the proposed legislative assertion that personhood begins at conception.

In fact, the philosopher who is arguably the most important philosophical defender of the pro-life position, Don Marquis, has argued that his case against abortion does not apply prior to implantation--precisely because of the twinning issue. And the reasoning here (which has been laid out by a number of philosophers, including Peter Singer) has clear implications for Oklahoma's so-called Personhood Bill.

Since I've talked about the Personhood Bill on this blog, I thought I'd spend a few moments connecting the dots between this bill and some of the philosophical arguments that relate to it. Let's start with Don Marquis's anti-abortion argument.

Marquis recognizes that there are enormous problems in making one's moral case about abortion rest on the question of personhood. We simply don't have a clear enough understanding of personhood to do that. So, instead, Marquis begins by asking what is wrong with killing adults. What makes homocide so presumptively seriously immoral? His answer is this: it deprives someone of the future they would otherwise enjoy. And not just any future. It deprives them of a certain kind of future--what we'll call a human future.

But if the chief wrong-making property of killing an adult human being is that it deprives the individual killed of a human future, that immediately motivates Marquis's key question: What kind of future does a fetus have?

A human one, of course. All of us started out as fetuses. And every human fetus is on a developmental trajectorty to become "one of us," and as such has a future like ours. And this means that killing a fetus has the same wrong-making property that killing an adult has.

Now there are various ways to object to Marquis's argument, but the one I want to focus on--the one that's interested me the most--has to do with identity over time. If you kill me, you deprive me of my future--the future I'd otherwise have. There is, in other words, a victim here. Someone who is being deprived of something they'd otherwise enjoy. And in order for there to be a victim, the one who enjoys the future in question has to be the very same individual as the one who is killed. Marquis's argument here depends on positing identity over time. The question is this: At what point does the organism who possesses a future like ours come into existence?

I'm inclined to say that this question is related to personhood (I've made an argument to this effect in conference presentations and have been working on a journal article on the topic). A necessary condition for A and B being the exact same individual is that A and B are essentially the same kind of thing. Since a person is an essentially different kind of thing than a corpse, the body that remains after I die won't be me. The question is when, on the other end of the course of my life, I came into being. I think the answer is this: whenever the biological organism developing in my mother's womb became a person.

And since the notion of personhood is difficult to explicate in uncontroversial terms, it follows that the question of when I came to be is a vexed one.

Marquis disagrees (and has expressed this disagreement in an e-mailed critique of my conference paper). He thinks that what is essential to me is not my personhood, but my status as a living human organism. So, on his view, when the living human organism came to exist, I came to exist (even if my personhood only came later). Given this view of things, Marquis thinks he can sidestep the vexing question of personhood and still argue that abortion is presumptively wrong.

But despite our differences on this issue, he and I would agree, I think, that if the organism has not yet come to exist, then neither has the person. And if the person comes to exist at conception, so does the organism.

Here is where Oklahoma's Personhood Bill becomes relevant. The Oklahoma state legislature is, in effect, poised to declare that the organism identical with me comes into existence at conception (and that this organism is a person to boot). According to this law, I came into existence the moment my father's sperm fertilized my mother's egg. I am identical with that zygote--we are the same individual at two different stages of development. Likewise, my student, "Tammy," is the same individual as the zygote from which she developed. And her sister, "Bri," is the same individual as the zygote from which she developed.

If this is true, then each of these zygotes would have been deprived of its future--a human one--had it been killed.  But even Don Marquis argues that this can't be.

And why not? Here's where twinning poses a problem. The problem is born out of what logicians call "the transitivity of identity." It's a basic logical rule that goes like this: If A=B and B=C, then A=C. In terms of individual organisms, if A is the very same individual as B, and B is the very same individual as C, then A is the very same individual as C.

So let's apply this rule to my student, Tammy, and her sister, Bri. As mentioned above, according to the Personhood Bill Tammy has to be conceived (pun intended) as the very same individual as the zygote from which she developed; and Bri has to be conceived as the very same individual as the zygote from which she developed. But Tammy and Bri are identical twins, identical in the sense of emerging from the same fertilized egg or zygote. According to the Oklahoma Personhood Bill, Tammy would have to be conceived as identical with that zygote, and Bri would have to be conceived of as identical with that zygote. By the rule of transitivity of identity, Tammy and Bri are the same person.

But they're not. Tammy greets me enthusiastically whenever we pass each other on campus. Bri has no idea who I am. I've seen them walking down the hall side-by-side, and I can assure you that they're not merely different people, but physically distinct biological organisms.

Marquis follows up this line of argument with another one: Much of the early "conceptus" (the product of conception) develops into what, later in pregnancy, is the placenta and other extra-embryonic structures(amniotic sac, umbilical cord) rather than any part of the fetus. These considerations, along with certain others, drive Marquis to the conclusion that the human organism comes on the scene only after implantation, when the embryo begins to differentiate itself from the extra-embryonic structures. This is still, of course, very early in pregnancy--usually before the person even knows they're pregnant; certainly before most abortions are performed. But not at conception.

If you embrace the Personhood Bill, you embrace the idea that I was a person when my father's sperm met my mother's egg--and hence that the organism that is me came into existence at that point. But holding that the organism exists at conception leads to absurd results in twinning cases; and there are important developmental milestones (the differentiation of embryo from the extra-embryonic structures being a crucial one) that could readily be understood as the point at which the organism emerges without leading to such absurd results.

In short, there are good philosophical reasons not to hold that the fertilized egg is a person--even if, like Marquis, we maintain that the fetus is a potential person (at least) by the time most abortions are being contemplated; and even if we hold, like Marquis, that being a human organism that is potentially a person means that killing it deprives it of a future like ours and so is presumptively very seriously wrong.

You can, in conclusion, take a strong stand against abortion without embracing this Personhood Bill. And the philosophical reasons not to regard the fertilized egg as a person are, to my mind, quite strong. In my last serious post on this subject, I argued that legislative fiat is not the best way to try to settle an essentially philosophical dispute. The kinds of arguments offered here constitute a better approach...and even the arguments of a well-known philosophical opponent of abortion speak against the currently proposed legislative pronouncement.