1 Introduction

What difference can the metaphysics of pregnancy make to the abortion debate? A lot. Or so I claim. In this paper, I argue that one promising account of pregnancy (which holds that, during pregnancy, much of the mother’s body is literally the part of the foetus), when paired with the standard pro-life claim that foetuses are persons with a right to life, has profound and far-reaching implications for the abortion debate.

2 Yancey on the Conditions for Bodily Parthood

In recent work, Hilary YanceyFootnote 1 has developed a distinctly Aristotelian account of the body and its partsFootnote 2. Ultimately, for Yancey as for Aristotle, ‘the body’ is just the matter that is informed or configured by a particular soul (characterized as the “substantial form” of a living thingFootnote 3).

Right out of the gate, Yancey’s account faces a problem: how do we determine whether a particular piece of matter is informed by a particular soul? That is, how do we tell if something is really, genuinely, a part of someone’s body? In most cases, the answers seem obvious. My ear is a part of me. Prince Andrew’s is not. My lungs are part of me. Zimbabwe is not. But some cases are less obvious. What should we make of prosthetic limbs, like artificial hearts or robotic hands? And what should we make of even messier cases, like mammalian pregnancy?

One way might be to look to our genes. If a piece of living tissue has the same genetic code as the rest of you, then it’s a part of you. But, on further reflection, genetic continuity seems to be neither necessary nor sufficient for something to count as a body part. Identical twins do not have each other as parts, so genetic continuity can’t be a sufficient condition for bodily parthood. And were I to solicit an organ transplant – a kidney, say – it would presumably be a part of me, not my donor; so it isn’t a necessary condition either. Genetic continuity might be a good rule of thumb for determining whether something is a body part, but it can’t guide us in every case.

In place of genetic continuity, Yancey proposes a twofold criterion. First, there’s functionality. Yancey writes:

[A] body part is some material object which performs a biological function proper for the human being (a function derived from the genetic material it has or should have). Body parts differ from mere tools in that the functions they perform are vitally connected to maintaining the life of the human being and her characteristic (that is, species-defining) activities. Body parts are configured by the soul in the sense that they are directed by the soul towards activities characteristic of the human being. And this, I will treat functionally. Body parts perform functions, act in characteristic ways in the pursuit and promotion of the telos of the human being.”Footnote 4

On its own, the functionality criterion is too inclusive. My glasses improve my vision by making it less blurry; in other words, they help my eyes to function properly. But my glasses aren’t part of me. If you broke them, you’d be guilty of property damage, not physical assault. Intuitively, it also seems plausible that a dialysis machine, say, is not a part of the person who uses it, even if it is actively replacing some characteristically human biological function.

If we want to affirm this intuition, we’d better introduce another condition, one that excludes things like dialysis machines but includes things like kidneys. One difference between the dialysis machines and kidneys is that dialysis machines are outside the skin whereas kidneys are inside of it. So, maybe, to be the body part of a particular human being, the part must be inside the skin or part of the skin itself.

Sadly, this condition suffers death by counterexample. For now, we’ll consider just one: proptosis, a condition of bulging or protruding eyeballs. If being behind the skin boundary is a necessary condition for bodily parthood, then the bit of the eye which protrudes beyond the eyelids of someone with proptosis ceases to be a part of their body whenever their eyes are open. But that’s not very plausible. Like genetic continuity, the skin boundary might be a good rule of thumb, but, again, nothing more.

Instead, Yancey proposes the following:

Here is a related but distinction condition on bodily parthood that captures, I think, the heart of the intuition behind rejecting a dialysis machine: necessarily, human body parts exist in an interdependent relationship with one another. Body parts work together for the advancement of the human being’s life and characteristically human activities. They depend on one another for the fulfillment of their characteristic functions. While a dialysis machine depends on the body to provide blood that it filters, one could plausibly think that this is insufficient to satisfy the interdependence condition. While the kidneys depend, for example, on a host of inputs from other organs (the liver, the stomach, the heart, the brain), the dialysis machine does not depend on such inputs for its operation and cannot (without external manipulation) adjust in response to changes in other organs.Footnote 5

So, Yancey thinks, there are two conditions that need to be met before something can be classified as the body part of a particular human. First, functionality: it must be performing some characteristically human biological function for the body as a whole. Second, interdependence: it must be in an interactive, interdependent relationship with other parts of the body.

3 The Metaphysics of Pregnancy

Given the degree of philosophical attention that’s been given to the moral and metaphysical status of foetuses, it’s surprising how little attention has been given to the situation in which most foetuses find themselves: pregnancy. But times are changing. A flurry of recent papers on the metaphysics of pregnancy have pulled the issue to the foreFootnote 6.

The pioneer of this new research program is Elselijn Kingma. According to Kingma, the debate over pregnancy can be carved, roughly, into two opposing viewsFootnote 7. The first is the ‘containment view’, so-called because it holds that the relationship between mother and foetus during pregnancy is merely one of containment: a foetus is merely contained within – but not part of – the maternal organism, in the way “a tub of yogurt is inside your refrigerator”Footnote 8.

The second is the ‘parthood view’, so-called because it holds that, during pregnancy, there is some sort of parthood relation between mother and foetus. This is the approach that Kingma defends. Specifically, Kingma argues that during pregnancy, the foetus is part of the maternal organism.

Judging by Kingma’s survey of the facts of pregnancy, she would no doubt agree that Yancey’s interdependence criterion is metFootnote 9. For the duration of pregnancy, the foetus is seamlessly connected to the placenta via the umbilical cord. The placenta grows directly “into (or out of) the uterine wall, just as a tail grows out of [a] cat”Footnote 10.

But what about the functionality criterion? What bodily function does the foetus perform for the mother? Kingma’s answer: the foetus functions for the mother’s body by enabling the performance of her reproductive faculties.

Without wanting to break my neutrality (I’m not going to endorse or reject any substantive metaphysical theses in this paper) I will note simply that some commentators have found this stage of Kingma’s argument unpersuasive. To them, it seems to put the cart before the horse. Yancey, for example, has responded that the foetus “is a result of reproductive activity” – “not its agent”Footnote 11, and Barry Smith has similarly responded that to say the function of the foetus is to enable the performance of the mother’s reproductive system “is a bit like saying the function of this biscuit is to enable the performance of the cooking function of my stove, or of my chef; or, the function of this gash is to enable the performance of the slashing function of my scimitar; or, the function of this engine air filter is to enable the performance of the engineering function of the automobile engineer”Footnote 12.

In light of this alleged weak spot in Kingma’s view, Yancey proposes an alternative theory. According to Yancey, if her account of bodily parthood is right, then our best evidence points not to the conclusion that the foetus is part of the mother, but, instead, to the conclusion that the mother’s body – or much of it – is, quite literally, part of the foetus.

As we have seen, pregnancy meets the interdependence criterion. But to see whose body is part of whose, we need to find out whose body parts are functioning for whose body. Kingma’s suggestion that the foetus functions for the maternal organism by enabling the performance of her reproductive faculties seems, some have said, to come up short.

But by contrast, as Yancey notes, the foetus depends on its mother’s “body in a wide variety of ways: hormonally, for oxygenation, growth, nutrition, antibody development and immunity”Footnote 13. For the duration of pregnancy, the mother’s body is geared to helping the foetus achieve its proper, characteristically human biological functions. In other words, the functionality criterion is met. For the duration of pregnancy, the mother’s body is part of the foetus’s.

There are a number of objections one could level against Yancey’s conclusion that, for the duration of pregnancy, the mother’s body – or much of it – is also part of the body of the foetus. Here, I will skim just a few and see how they might be resisted. (That’s not to say Yancey’s account is plausible or true. You can be the judge of that. All I want to show, for now, is that it shouldn’t be dismissed out of hand.)

First, you could object that the mother’s body isn’t a part of the foetus’s body because it has a different genetic code to the foetus. But as we’ve seen already, genetic continuity is not a necessary condition for bodily parthood: a transplanted organ is a genuine body part, even though it’s genetically distinct from the rest of the recipient’s body.

Second, you might object that since the mother’s body will eventually become detached from the foetus’s body, it’s implausible to think that the former is really part of the latter. “But”, as Kingma points out, “this argument is obviously fallacious: it conflates a possibility with its actualisation. The fact that the glass could be broken does not mean it is broken now; nor does the fact that I am mortal make me dead. Similarly, an organ has many parts, such as hair, blood and kidneys, that can be separated from it; the potential for separate existence doesn’t preclude parthood”Footnote 14.

Third, there’s the problem of the incredulous stare. At first blush, Yancey’s thesis seems bananas. If true, it would mean that for the duration of pregnancy a foetus has two hearts, two digestive systems, four lungs, and, even if it’s male, a fully functioning uterus, all of which seems crazy. Is it crazy?

Well, after decades of pro-lifers waving around placards displaying images of wholly detached, biologically independent, White-as-the-clean-driven-snow foetus-babies, it’s not surprising that Yancey’s view initially strikes us as unintuitive, at least at first blush. But what does this intuition reveal exactly? Plausibly, not much. You could, with some justification, make the case that the degree to which our intuitions about pregnancy have been culturally contaminated gives us a reason to doubt that, in this case, they’d serve as reliable guides to metaphysical realityFootnote 15. Besides, intuitions can be subject to defeat: if Kingma’s and Yancey’s arguments for the parthood model are persuasive enough, then those intuitions should be put to one side.

Fourth, you might object that there is a tension between Yancey’s account of pregnancy and the thought that pregnant women have substantive rights over their bodies. But, since pregnant women do have substantive rights over their bodies, Yancey’s account must be falseFootnote 16. In reply, I am skeptical that there is such a tension, at least not in any unique or robust sense. Consider a pair of twins, Dwight and Jim, who are conjoined and share a heart. (I chose two men for my example to highlight that the principles I’m appealing to, however we chose to cash them out, are entirely gender non-specific.) Surely, in this example, both Dwight and Jim have substantive bodily rights over their shared heart. Granted, we might think that Dwight and Jim’s bodily rights are less exclusive than those of two twins who were born apart. (On a distinct but related note, Alexander Pruss has confessed to the intuition that “the shared organs of Siamese twins are less fully the organs of either to the extent that the other twin is permitted to make use of them”Footnote 17). Nevertheless, the fact remains: even if we think that to share organs with someone else makes those organs less fully our own in some important sense, Yancey’s view of pregnancy does not commit you to saying, implausibly, that pregnant women lack substantive rights over their bodies.

Fifth, you might object that Yancey’s view commits us – controversially – to a hylomorphic account of personal identity (which says each of us has a ‘soul’, that is understood, in some sense, to be the form of the body – whatever that means.) But since hylomorphism is very much a minority view, it follows that Yancey’s account will only appeal to a small audience.

Granted, Yancey does appeal to hylomorphism to make her case. But this, by itself, doesn’t prove much. The objection only succeeds if we have reason think that the essentials of Yancey’s view cannot be defended outside of hylomorphism. But, absent some further argument, I see no reason to think this.

Indeed, something very much like Yancey’s view has already been arrived at independently by Alexandria Boyle, who argues that if we adopt a metabolic view of the organism – one on which something is a part of an organism if it is functionally integrated with the organism’s other parts, and collaborates with them in metabolism – then many of the mother’s body parts (in particular, the mother’s kidneys, heart, placenta, and lungs) should be counted as parts of the foetus as wellFootnote 18. Boyle’s view is compatible with various versions of hylomorphism, no doubt, but no explicit appeal to it (or any other controversial metaphysical thesis) is madeFootnote 19.

Finally, you might object that Yancey’s thesis is in fact ruled out by hylomorphism. Here’s why that might be: according to some hylomorphists, no substance can be the proper part of another substanceFootnote 20. On this view, if a substance – a molecule, say – becomes part of the body of a cat, then the molecule loses its substantial form and becomes subsumed by the substantial form of the cat. In some sense, the particle ceases to exist. It becomes a mere ‘virtual particle’, a particle in name only, being “fully yoked”Footnote 21, as it were, to the substance in which it now participates.

If the view that no substance can have another substance as a proper part is correct, then Yancey’s view of pregnancy will run into some difficulties. At first blush, it’s hard to see how a doctrine like this could be squared with the possibility of two complete substances sharing parts in common, even if those parts are only ‘virtual’ in natureFootnote 22.

On the assumption that the ‘no substance can be composed of other substances’ doctrine really does imply that substances cannot overlap, it would seem that if the doctrine is accepted there will only be three options on the table when it comes to pregnancy:

  1. (1)

    The mother and the foetus are separate, non-overlapping substances. (This is basically just a restatement of the containment view, which both Yancey and Kingma reject).

  2. (2)

    The foetus is subsumed by the substantial form of the mother, losing its substantial form upon implantation, and then regaining it after birth.

  3. (3)

    The mother is subsumed by the substantial form of the foetus, losing her substantial form upon implantation, and then regaining it after birth.

The only option here that is consistent with Yancey’s claim that the mother’s body is part of the foetus’s is option (3). But option (3) seems highly implausible. Think about it: if the mother loses her substantial form upon implantation, then in some important sense she ceases to exist. Do pregnant women not really exist? This seems implausible. Thus, contra Yancey, hylomorphism excludes the possibility of the mother’s body being part of the foetus inside of her.

However, three responses can be made to this. First, although Yancey relies on a distinctly hylomorphic framework to make her case, I don’t see why her view of pregnancy couldn’t be derived from some other, less controversial account of the body and its parts. Second, the ‘no substance can be composed of other substances’ doctrine, while fairly popular, is far from ubiquitous. Plenty of hylomorphists reject it.Footnote 23 Third, even if the doctrine turns out to be true, this wouldn’t necessarily entail that two substances cannot overlap, despite what I said earlier.Footnote 24

In response, you might object that the claim that two substances cannot overlap is true by definition. This is because, traditionally, philosophers have held that “[t]wo individuals overlap mereologically if and only if they have a part in common”Footnote 25. But if substances don’t have any proper parts, then, by definition, it’s impossible for them to overlap.

This is a solid argument as far as it goes. If substances don’t have any proper parts they can share between them, then any sense in which they can be said to ‘overlap’ will have to be somewhat revisionary. But that wouldn’t be the worst thing in the world. Why would it matter if a definition is revisionisary if it captures what we mean in a useful enough way?

One such revisionist account, which was suggested to me by Josh Rasmussen in correspondence, is to analyze the ‘overlap’ of substances not in terms of shared parts, but in terms of shared space. If this idea makes sense, and I’m not sure why it wouldn’t, then the problem goes away. Even if no substance can be part of another substance, they might still be able to overlap spatially. And if it’s possible for substances to overlap spatially, then the gist of Yancey’s view should still be able to get off the ground, at least to the degree that I need to motivate my argument.

More objections could be made, and more responses could be givenFootnote 26. My only point is that Yancey’s view is serious business and deserves at least a fair hearing. In the next section, I’ll argue that if Yancey’s thesis is true, then, on the assumption that the foetus is a person with a right to life, a popular family of arguments for legal abortion will become significantly harder to defend.

4 Boonin’s Defence of Abortion

In his 2019 masterpiece, Beyond Roe: Why Abortion Should be Legal—Even if the Fetus is a Person, David Boonin argues that abortion should be legal, even if the foetus is a person. He opens with an analogy. Consider the real-life case of Robert McFall, an asbestos worker from Pittsburgh who, in 1978, was diagnosed with aplastic anaemia. If he couldn’t get hold of a bone marrow transplant, doctors told him, he would die. Fortunately for McFall, those doctors soon found a candidate whose tissue might just be compatible with McFall’s body – his cousin, David Shimp. Unfortunately for McFall, midway through the testing process, Shimp got cold feet and said he’d prefer not to donate his bone marrow to McFall. Desperate, McFall took his cousin to court. The case of McFall v. Shimp was fought in the July of that year.

The fight didn’t last very long. McFall’s plea fell on deaf ears. The Judge – Judge John P. Flaherty Jr. – was singularly unimpressed. He wrote: “For a society which respects the rights of one individual, to sink its teeth into the jugular vein or neck of one of its members and suck from it sustenance for another member, is revolting to our hard-wrought concepts of jurisprudence”Footnote 27. McFall’s request for a preliminary injunction was denied. Fifteen days later, he was dead.

Presumably, your intuitions are the same as those of the Judge. It would have been nice of Shimp to give McFall his bone marrow. His refusal to donate seems cold-hearted, unsporting, selfish, and cruel. Even Judge Flaherty thought it was “morally indefensible”Footnote 28. Yet, we think, it would still be wrong for the state to force Shimp to undergo an invasive procedure to donate bone marrow to his cousin. His marrow, his choice.

But notice: there’s nothing sacred about bone marrow. The argument seems to apply just as well to other body parts; a kidney, a lung, or – drum roll, please – a uterus. Thus, Boonin argues, just as it would be wrong for the state to force Shimp to procure a bone marrow transplant to his cousin, so too would it be wrong for the state to force a woman to undergo the considerably more demanding process of carrying an unwanted pregnancy to term.

There are several purported disanalogies between the case of Shimp and McFall and the case of abortion, many of which Boonin deflates admirably in his book. Here, however, I want to focus in on just one: the killing-versus-letting-die objection.

According to this objection, there is a relevant difference between the case of Shimp and McFall and the case of pregnancy, one that undermines Boonin’s entire case – namely, that while abortion involves actively killing the foetus, Shimp’s refusal to donate bone marrow to McFall merely leaves McFall to die. Thus, the objector argues, Boonin is comparing apples with oranges, not like with like.Footnote 29

In response, Boonin raises a killer objection. Many methods of abortion, he concedes, do involve actively killing the foetus. For example, dilation and curettage abortions involve emptying the contents of the mother’s womb by suction, or with a tool called a curette, which pulls the foetus apart piece by piece.

But, notes Boonin, not all methods of abortion are like this. Hysterotomy abortions involve removing the foetus from its mother’s womb through a small abdominal incision in the uterus. And the abortion pill (comprised of two medications: mifepristone and misoprostol) works by causing the lining of the uterus to deteriorate and then inducing a miscarriage.

In the latter two methods, Boonin ventures, abortion does not resemble an active killing so much as mere letting die. A withdrawing of life support. An unplugging. But, as Boonin points out, not many pro-lifers are going to oppose only those methods of abortion that involve actively dismembering the foetus. They’ll probably want to oppose all abortions, regardless of how they’re done. Therefore, to consistently oppose all abortions, pro-lifers must dispense with the killing-versus-letting die objection.

In response, the pro-lifer might object that abortions done by hysterotomy and the abortion pill are still an active killing, not a mere letting die. As Boonin words their objection: “You might think removing a foetus intact from a woman’s uterus when there’s no way the fetus can survive without using her uterus really amounts to killing the fetus and not just to letting the fetus die”Footnote 30.

But this objection plausibly fails. To see why, consider an altered version of the case that Boonin contrives:

Suppose a few days after telling McFall he was unwilling to let him use some of his bone marrow, Shimp went down to the hospital to visit him. Suppose when Shimp got there, McFall had already been hooked up to a bone marrow transferring machine in the hope that Shimp might change his mind. Suppose, in addition, the floor in McFall’s room had recently been cleaned, washed, and polished and was extremely slippery as a result. Before Shimp entered the room, in fact, he was warned: “The floor in there is extremely slippery. If you walk in there, you might slip and fall and get stuck to the bone marrow transferring machine. And if that happens, it will start removing some of your bone marrow and transferring it to McFall.” Suppose Shimp decided to take his chances despite this warning just because he thought it would be fun to visit his cousin. He put on special nonslip shoes and tried to walk very slowly, but he still ended up slipping and falling and getting stuck to the machine. As a result, Shimp is now lying on the floor next to McFall and the machine is removing some of his bone marrow and giving it to McFall.Footnote 31

Presumably, your intuition here is that while it would be nice of Shimp to remain connected and continue transferring bone marrow to his cousin, he still has a right not to. And if that’s the case, Boonin argues, then pregnant women likewise have a right to obtain abortions by pill or hysterotomy.

Clever though it is, this last maneuver won’t work if Yancey’s view of pregnancy is right. For if Yancey’s view of pregnancy is right, then much of the woman’s body is literally part of the foetus’s body. If this point is accepted, Boonin’s attempt to distinguish between methods such as dilation and curettage abortions on the one hand, and abortion via pill and hysterotomy on the other, falls by the wayside.

A hysterotomy abortion, for example, is not merely the removal of one body from inside another, but the removal of a body – the foetus’s body – from its own body. An act of dismemberment. Thus, to prematurely force a foetus out from inside its mother’s body is like forcibly evicting a man from his own skin or unplugging him from his brainstem.

In summary, then, if Yancey is right, the killing-versus-letting-die objection to Boonin’s argument for legal abortion can be shielded from his critiques. Perhaps the objection will turn out to fail for some other reason. But if Yancey’s thesis turns out to be true, it won’t be for the reasons Boonin gives.

5 Implications for Implantation

Some pro-lifers oppose certain forms of birth control (Plan B, IUDs) on the grounds that, sometimes, they might prevent the early embryo from implanting in the uterus.

Whether these claims are factually true needn’t concern us. What matters is the principle of the thing. Suppose we invent a drug whose sole purpose is to prevent blastocysts from implanting in the uterus. Should it be legal (in theory at least) for a woman to take the drug, fully in the knowledge that doing so will block implantation, and fully in the knowledge that a blastocyst which fails to implant will die?

As we have seen, part of the answer may depend on the further question of whether the mother’s body is part of the embryo. As far as I’m aware, this question has not been given much philosophical attentionFootnote 32. Still, by my lights, the most promising answer seems to me to be no. Prior to implantation, the embryo is merely contained within the body of the mother. There is no parthood relation at all.

A case could be made that Yancey’s functionality criterion is met. In the days leading up to implantation, the fallopian tube provides the travelling blastocyst with a warm, protective, nutritive environment, and millions of cilia – the tiny hairs lining the fallopian tube – serve to waft it gently on its way.

Suppose we grant this point. It still seems that Yancey’s interdependence criterion is left unsatisfied. No topological connection exists between the mother’s body and that of the embryo, which travels through the fallopian tube free and unfettered, like a train in a tunnel or a pellet in a peashooter. The two bodies just don’t seem to be interdependent in the right way.

Thus, prior to implantation, there’s a strong case to be made that on Yancey’s account, there is no parthood relation (or relation of overlap) between the mother and the embryo. The latter is merely contained within the former, like a bun in the oven or a yogurt pot in a fridge. If that’s right, the legality of abortions done by way of blocking implantation cannot be resisted in the way I’ve outlined above, supposing the line of argument defended by Boonin is persuasive. Perhaps it’s not and can be resisted in some other way. But it won’t be resistible in the way I’ve been exploring here.

6 Conclusion; or Three Reasons Why this Matters

In this paper, I have defended a conditional claim: if we pair Yancey’s view pregnancy with the pro-life claim that the foetus is a person with a right to life, then Boonin-style bodily rights arguments for permitting post-implantation abortions will become much harder to defend. This is because Boonin’s argument hinges on the claim that there are post-implantation abortion methods that don’t involve actively killing the foetus. But this is a claim that, if Yancey’s view of pregnancy turns out to be true, will ultimately turn out to be false.

A lot has been written on the ethics of abortion. Possibly too much. So let me conclude with three reasons to think that the argument of this paper, if it succeeds, matters for the debate going forwards.

First, if, like me, you are inclined to think that all of the existing pro-life responses to Boonin-style bodily rights arguments are unpersuasive, then the argument of this paper shows that the pro-life position is not dead yet. There is still something to be said in its defense.

Second, the argument of this paper, if it succeeds, raises the intellectual price-tag of accepting Boonin-style bodily rights arguments. Before now, defenders of such arguments only had to take substantive positions on moral questions. If what I’ve said is right, then they will now need to take a substantive negative position on a metaphysical question and maintain that Yancey’s view of pregnancy is false.

And third, it’s likely that the philosophers who defend the view that the foetus is a person with a right to life are also going to be the of philosophers who’ll be sympathetic to Yancey’s view of pregnancy. The reason I think this is that, as Yancey’s work reveals, such a view of pregnancy flows quite naturally from a hylomorphic view of personal identity, which, for one reason or another, many of the most prominent philosophical proponents of the pro-life position today endorse. This is partly because a lot of work has been done arguing that hylomorphism is well-suited to a pro-life positionFootnote 33. (Indeed, the pro-life view that the foetus is a person is often referred to by its defenders as the ‘substance view’, language which, in context, is overtly Aristotelian.) It is also partly because many of the most prominent pro-life philosophers are Catholics, and Catholics have been doctrinally committed to hylomorphism, or something very much like hylomorphism, ever since the Council of Vienne. Thus, it’s not unreasonable to think that many contemporary pro-life philosophers will be attracted to Yancey’s view of pregnancy, since, arguably, it flows quite naturally from a view of personal identity that lots of them are already inclined to accept.

If that’s right, then both sides of the abortion debate have reason to pay attention. Pro-lifers have reason to pay attention because, should they turn out to be sympathetic to Yancey’s view of pregnancy, they stand to gain powerful a new dialectical tool for defending the pro-life position. And pro-choicers have reason to pay attention too because, if pro-lifers end up adding this tool to their belt, pro-choicers will want to engage with the strongest arguments that their philosophical opponents have to offer.