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Answering Three Common Arguments for Abortion

Filed under Morality


NOTE: The following post, the second of two from Trent Horn, is excerpted from a new book he will publish in September defending the pro-life position. Read the first post here.

In Part 1 of this short series, we saw that there isn’t a way to consistently define what a “person” is that includes newborns but excludes fetuses and non-human animals. In this post I will examine “body-rights” arguments for abortion that take advantage of the difference between newborns and the unborn in terms of the use of the mother’s body during pregnancy. These arguments either admit the unborn are persons or say the question doesn’t matter and merely assume the unborn are persons for the sake of the argument.

There are really two arguments in this vein and I believe neither works.

The “Sovereign Zone” Argument


“Women have the right to have an abortion because women (and men) have the right to do whatever they want with their bodies, or at least, do whatever they want to whatever is inside of their bodies.”

The problem with this argument is that the premise (complete bodily autonomy) is more controversial than the conclusion (abortion should be legal). How do we know we have complete bodily autonomy? This argument is on par with saying, “Slavery is moral because is have the right to own anything I want.” Just as we should be skeptical of the premise “I can own anything” we should be skeptical of the premise “I have the right to do whatever I want with my body.”

The pro-choice philosopher Mary Anne Warren writes,

“The appeal to the right to control one’s body, which is generally construed as a property right, is at best a rather feeble argument for the permissibility of abortion. Mere ownership does not give me the right to kill innocent people whom I find on my property, and indeed I am apt to be held responsible if such people injure themselves while on my property. It is equally unclear that I have any moral right to expel an innocent person from my property when I know that doing so will result in his death.”1

The U.S. Supreme Court even rejected this argument in Roe v Wade. Justice Blackmun wrote,

“In fact, it is not clear to us that the claim asserted by some amici that one has an unlimited right to do with one’s body as one pleases bears a close relationship to the right of privacy previously articulated in the Court’s decisions. The Court has refused to recognize an unlimited right of this kind in the past.”2

I can’t think of any other right that is absolute in the way that defenders of the sovereign zone argument claim the right to control one’s body is absolute. No one has an absolute right to free speech; we ban shouting “Fire!” in a crowded building when there is no fire. No one has the absolute right to engage in illegal religious activities under the guise of “freedom of religion.” Laws against illicit drug use, prostitution, selling organs, public urination, and indecent exposure show there is no absolute right to do anything we want with our bodies.

In fact, all it takes to refute this argument is one example that shows we cannot do whatever we want with our bodies. If that principle is refuted, then so is the sovereign zone argument. Here’s one thought experiment that I think shows we do not have unlimited bodily autonomy over that which lives inside of us.

If it is possible to remove a late-term fetus and keep him alive in an incubator, then, theoretically, if the technology existed, one could take a premature infant from an incubator and transfer him into a woman’s uterus. Nearly everyone agrees that it would be wrong to kill the child in the incubator. But according to the sovereign zone argument, it would not be wrong to kill that child after he was transferred back into the sovereign zone of the womb. It is ridiculous that an infant could be treated like a human being in one location (the incubator) and like disposable property in another (the uterus).

Finally, the argument admits that the fetus is a person who, by the argument’s own logic, has a right to bodily autonomy. If we would respect the bodily autonomy of a sleeping or unconscious born person by not killing him, then wouldn’t we bound to treat an unborn child in the same way because they too, as a person, have a right to “bodily autonomy?”

Regardless of the status of unlimited bodily autonomy, the sovereign zone version of the bodily rights argument fails to support legal abortion.

The “Right-to-Refuse” Argument

This version of the argument says that maybe you can’t do anything you want with your body, but you have the right to not let your body be used as life support in order to keep another person alive (such as the refusal to donate bone marrow to save a dying person).

The biggest problem with this kind of argument is what’s called the responsibility objection. In the case of a stranger who will die unless I donate blood or bone marrow, I am not obligated to help him, because I was not involved in how he became ill. But if I caused another person to become dependent on me, then I would owe him assistance.

Here’s an analogy that might help illustrate what I mean. Imagine a replicator machine that can create any kind of object. If I activate the replicator, there is a high chance that the machine will dispense $10,000. There is also a chance that along with the money the machine will dispense a healthy newborn infant.3 If you could find no one else to care for this child, you would become the guardian or “parent.”

Why? Because you engaged in an act that you knew could create a helpless human being, and now that human being stands in need of your assistance. Abandoning this infant to die would simply never be tolerated. Michael Tooley argues in his book defending the morality of both abortion and infanticide:

". . . the anti-abortionist can argue that although people in general may be under no moral obligation to allow the fetus the use of their bodies, even when it is necessary if the other individual is to survive, a pregnant woman is, in general, under a moral obligation to allow the fetus the use of her body, since she is morally responsible for there being a fetus that stands in need of a life support system.”4

While the replicator is a science fiction example, we can also use the rare though real example of women who do not know they are pregnant until they give birth. If the autonomist believes that we have no obligation to the children we create, then there is no reason a mother who unexpectedly gives birth to a child in a field could not simply leave the child there.

Suppose a woman lived in a country where abortion was illegal or she could not afford to pay for an abortion. Upon giving birth at home could she simply abandon the child or “refuse to provide life-giving bodily aid” in the form of breast milk? If this woman does have a responsibility to care for this child because she was responsible for his existence, then it follows she would be responsible for that same child when it came into existence at conception and abortion would be morally wrong.

I’ve heard arguments in response to this objection that say engaging in sex doesn’t “cause” pregnancy because not everyone who has sex becomes pregnant. The critic also says that there are many factors outside of a woman’s control that influence whether she becomes pregnant so we can’t say she “caused” a child to come into existence that needs her help when she chose to have sex.

But that is like saying that drinking large quantities of alcohol and driving doesn’t cause pedestrians to be hit by drunk drivers because some people drink and drive and no one gets hurt. Furthermore, there are also factors outside of the driver’s control that affect whether a person gets hit (like whether other people are on the road or not). Therefore, we can’t say drunk drivers cause drunk driving fatalities.


Drinking alcohol impairs a person and initiates a chain of events that is likely to lead to traffic fatalities. Even if the person took measures to avoid getting into an accident (e.g. playing the music loudly, rolling the window down) he or she is still responsible for the fatality that was caused.

Finally, this response would make it futile to collect child support from deadbeat dads since they could always claim that they aren’t truly “responsible” for the children they sired since they didn’t intend to have those children when they chose to have sex. If we expect men to be responsible for children they create (intentionally or unintentionally) through intercourse, then shouldn’t women be held responsible for the children they create through intercourse as well?

The Organ Use Objection

“But,” says the critic, “What if the traffic victim needs your blood, or your own child needs a bone marrow transplant that you knew would be required before they were conceived? Are you obligated to donate your body in those cases?”

Here is where another important difference arises between pregnancy and these cases. In organ donation cases, I use a part of my body that was not made for the sick person in order to keep him alive. I am resorting to extraordinary means to save him, since the purpose of my kidneys, for example, is to filter my own blood and not anyone else’s. By my withholding the use of my kidneys, the sick person dies. But I am not the cause of his death; I have merely chosen not to save him. Is abortion a similar act of withholding an extraordinary use of an organ?

Even in a nonreligious framework it makes sense to say things like, “The purpose of the heart is to pump blood” or “The purpose of the lungs is to absorb oxygen.” Some people may deny that our organs have any “purpose” or are “for” anything, but I don’t think they would hold that attitude should their own organs become damaged or infected. In order to say an organ isn’t working properly would seem to imply that the organ has a proper way of functioning, or a “purpose” or “end” in its operations that is not being achieved.
 The uterus’s purpose seems clear: to support the life of an unborn child. Otherwise, why is it even inside the body at all? If the uterus is designed to sustain an unborn child’s life, don’t unborn children have a right to receive nutrition and shelter through the one organ designed to provide them with that ordinary care?5

Unlike in the organ donation cases, where I fail to save someone who is dying, abortion involves separating a healthy child from what it requires to live. Abortion is not an act of “failing to save” but is an act of killing that deprives a child of its right to live safely.6 It is on par with putting your infant out in a snowstorm that directly kills him and does not “fail to save (him) from an environment in which (he) cannot survive.”

A critic may object that pregnancy is not “ordinary care” because it causes the woman’s body to undergo extraordinary and uncomfortable transformation. But it is a transformation toward which women’s bodies are naturally ordered. Puberty also involves large-scale and uncomfortable changes to the body, but no one says puberty is an “extraordinary” event on par with organ donation (indeed, it would be extraordinary if it did not happen).

Likewise, throughout all of human history, fertility and pregnancy were considered ordinary events, and anyone reading this page was involved in such an event. Providing shelter and nutrition in the womb is simply an ordinary amount of care (even if at times it can be painful or uncomfortable) that we expect parents to provide to their unborn children.


I think I’ve shown that there are no morally relevant differences between humans before they are born or can survive outside of the womb and humans just after they are born. As one child development book puts it, “The fourth trimester [the three months after birth] has more in common with the nine months that came before than with the lifetime that follows.”7

We therefore should either treat newborns like fetuses and make it legal to kill them simply because they are unwanted, or we should treat fetuses like newborns and make it illegal to directly kill them because they are unwanted.
(Image credit: Tribune News)


  1. Mary Anne Warren, “On the Moral and Legal Status of Abortion” The Monist, 57, no. 4, 1973.
  2. As examples of this refusal Blackmun lists Jacobson v. Massachusetts, 197 U.S. 11 (1905) (vaccination) and Buck v. Bell, 274 U.S. 200 (1927) (sterilization).”Roe v Wade 410 U.S.113 Section VIII.
  3. Scott Klusendorf, The Case for Life (Wheaton, IL: Crossway Books, 2009), 195. Keep in mind that I don’t use this illustration to mean that women are just “baby-making machines.” It’s an analogy.
  4. Michael Tooley. Abortion and Infanticide (Oxford: Oxford University Press, 1983) 45.
  5. See also Stephanie Gray, “A Kidney versus the Uterus” Ethics & Medics 34 no. 10 (October 2009).
  6. This is also known as the “killing vs. letting die” objection, which I have subsumed into the “organ use objection.” Under my view, denying someone the extraordinary use of an organ in order to keep them from dying from an unrelated ailment is a moral case of “letting die” while denying someone the ordinary use of an organ they need to survive is an immoral case of killing.
  7. Susan Brink. The Fourth Trimester: Understanding, Protecting, and Nurturing and Infant through the First Three Months. (Berkeley: University of California Press, 2013).
Trent Horn

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Trent Horn holds a Master’s degree in Theology from the Franciscan University of Steubenville and is currently an apologist and speaker for Catholic Answers. He specializes in training pro-lifers to intelligently and compassionately engage pro-choice advocates in genuine dialogue. He recently released his first book, titled Answering Atheism: How to Make the Case for God with Logic and Charity. Follow Trent at his blog, TrentHorn.com.

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