• Strange Notions Strange Notions Strange Notions

Can Atheists Defend Abortion Without Defending Infanticide?

Filed under Morality


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

Let's begin by noting that while not all atheists are pro-choice, a sizable majority are. In fact, a recent Gallup poll revealed that those with no religious attachment are the most likely demographic to identify as pro-choice.

With that in mind, let me present what I think is the strongest argument for the moral and legal permissibility of abortion, often made by atheists:

“Pro-life advocates say that abortion is wrong because the fetus or embryo has human DNA. However, merely possessing human DNA doesn’t make it wrong to kill something because then it would be wrong to kill gametes (sperm and egg) or tumors that also have human DNA. Instead, it is wrong to directly kill innocent persons.”

But what is a person?

“A person is any being who is capable of rational thought and/or self-reflection. Since fetuses and embryos are clearly not persons due to their inability to engage in rational thought, it follows that abortion is not immoral and should remain legal.”

Sounds like a familiar argument so far. What makes it hard to refute is if you tack this part on to it:

“Yes it’s true that newborn infants cannot engage in rational thought that surpasses higher-order animals like pigs or dogs, which are also not persons. But this only means that newborn infants are not persons. Just as it is not immoral to euthanize a pet because it is unwanted, it is simply not immoral to euthanize an infant that’s unwanted because infants aren’t persons.”

Michael Tooley famously defends this view in his 1982 book Abortion and Infanticide. Peter Singer defends a limited view of infanticide and several years ago the issue came up in the media with the publication of a journal article defending “after-birth abortion.”

What makes this argument hard to refute is that it is consistent. You have to dig deep with the argument’s metaphysical assumptions about persons to show what’s wrong with it instead of just pointing to a repugnant conclusion of the argument.

But what about the pro-choice atheist who thinks infanticide is wrong? Can he consistently defend legal abortion without opening the door to infanticide? I don’t think so and here’s why.

The Worst Pro-Choice Arguments

The following arguments that defend abortion without allowing for infanticide are very bad and pro-choice philosophers know it. Even still, they are common so I’d like to get them out of the way right now.

Abortion should be legal because women have a right to choose.

If by “right to choose” you mean “right to have an abortion,” then you’re using circular reasoning. You’re saying, “Abortion should be legal because women have the right to have an abortion.” The conclusion is being used to support the premise and the argument is now invalid. However, if by “right to choose” you mean something like “right to control one’s body” then see my comments on bodily rights arguments at the end of this post.

Abortion should be legal to help alleviate overpopulation, poverty, and child abuse.

Should we also kill the homeless and the disabled in order to alleviate those problems as well? Unless the pro-choice advocate can show the unborn are not persons while born people are persons who can’t be killed to ease social problems, then this argument just assumes it’s permissible to kill fetuses and not permissible to kill infants (and other born people). It’s missing a reason that justifies killing fetuses because the world is overpopulated, but not born people.

Don’t like abortion, don’t have one!

If you don’t like firing someone because they identify as being gay then don’t fire them, but don’t take away another person’s right to choose to discriminate against these people. See what I did there? If we don’t have the right to discriminate against, harm, and especially kill, born persons, then we don’t have the right to do the same to the unborn unless one can show they are not persons.

The unborn are not human like an infant. They’re just embryos/fetuses or a clump of cells.

If by “human” you mean “person” I’ll get to that in a moment. If by “human” you mean “an individual member of the species homo sapiens,” then this is just patently false. David Boonin, in his book A Defense of Abortion writes,

“Perhaps the most straightforward relation between you and me on the one hand and every human fetus on the other is this: All are living members of the same species, homo sapiens. A human fetus after all is simply a human being at a very early stage in his or her development.”1

Peter Singer also holds this view and writes,

“It is possible to give ‘human being’ a precise meaning. We can use it as equivalent to ‘member of the species Homo sapiens’. Whether a being is a member of a given species is something that can be determined scientifically, by an examination of the nature of the chromosomes in the cells of living organisms. In this sense there is no doubt that from the first moments of its existence an embryo conceived from human sperm and eggs is a human being . . .”2

Finally, embryo and fetus refer to the stages of development in a human being’s life, so they don’t disprove an entity is not a human organism. Likewise, the unborn are not “clumps of cells” but complex cooperating cellular units that develop for the good of the whole organism. If the unborn are clumps of cells, then so are we.

Abortion should be legal otherwise women will die in back alley abortions.

How does the danger involved in a bigger person killing a smaller person justify making legal for the bigger person to kill the smaller person? The pro-choice philosopher Mary Anne Warren says of this argument, “The fact that restricting access to abortion has tragic side effects does not, in itself, show that restrictions are unjustified since murder is wrong regardless of the consequences of prohibiting it.”3

You’re a man.

So men can’t have an opinion on this issue? (No, they just can’t have an opinion that takes away women’s rights!) Oh . . . so they just can’t have a pro-life opinion since you would not be upset at a man speaking out in defense of abortion (like the nine male justices who decided Roe v. Wade). In any case, just pretend I’m a woman making the same arguments.

The main issue: What is a person?

Now, for a lot of these arguments a pro-choice reader might be screaming, “But killing toddlers, the homeless, and the disabled is different than killing fetuses!” This is because many pro-choice advocates believe the former are persons but the latter are not. But do they have an argument to justify that belief? More importantly, can they consistently show the unborn are not persons without showing that newborns are not persons either?

Let’s try out some sample definitions of what a person is and see if they work:

Before I get started I want to point out a bad way of defining “personhood” that I often see among pro-choice advocates. Instead of offering a definition for personhood they will just offer a disqualification. They might say, “A person can’t be the size of a grain rice”; “A person can’t be an immobile unthinking blob of cells”; or “It’s just obvious embryos aren’t persons!”

Okay, but don’t tell me what’s not a person; tell me what is!

In order to say fetuses and embryos are not persons you already have to know what a person is in order to disqualify them from being considered persons. For example, we can say a snake is not a mammal because it lacks the traits a mammal must possess (like being warm-blooded). We only know snakes aren’t mammals because we already know what mammals are.

Likewise, we have to know what a person is in order to say embryos and fetuses are not persons. So are there any definitions of what a person is that excludes embryos and fetuses without excluding infants?

A person is any being that can engage in rational thought.

This definition excludes the unborn along with the newborn (and the long-ago born) who can’t engage in rational thought.

A person is any being that has the potential to engage in rational thought.

This definition includes the newborn as well as the unborn so it can’t be used to defend abortion. You might counter that newborns have primitive brains while embryos do not have ay kind of brain at all (fetuses have a small, primitive brain). According to Nature magazine, a newborn’s brain increases from 56 trillion synaptic connections to 1,000 trillion at nine months after birth. If we grant newborns are persons even though their brains still have a lot of developing to do, then why not grant the same status to the unborn that also just have more of the same kind of developing to do?

How could the amount of time it takes to grow a fully functioning brain affect one’s moral status? Why does the newborn’s undeveloped non-rational brain grant it special rights but the fetus’ undeveloped non-rational brain, or even the embryo's genetic code to make a rational brain, not grant those beings the same rights? Why does the stage of an undeveloped organ’s growth change a being’s moral worth?

A person is any being that can feel pain.

This definition excludes most embryos and fetuses, as well as adults suffering from congenital insensitivity to pain. Also, it includes non-human animals like rats. It makes running over a chipmunk and fleeing the scene a felony.

A person is any being that is born.

Cats and dogs are born. Are they persons?

A person is any being that can survive outside of the womb.

This definition has the same problem as the previous two definitions.

A person is any human organism that can survive outside of the womb.

This is just circular reasoning at its finest. “A human organism that can survive outside of the womb” is the same thing as “not a fetus” (this also applies to the definition of personhood being “any human organism that is born” as well). This argument just says, “A person is not a fetus because a fetus is not a person.” But that’s like saying women aren’t people because a person is any human that has a Y-chromosome.

In the absence of any supplemental reasons to justify the claim that birth or Y-chromosomes matter, these arguments are simply fallacious.

A person is any human organism that does not depend on the body of another human organism in order to survive.

Why should we believe this criterion is correct? How does the way a person survives change their moral status?

In the year 2000, a British court had to decide what should be done with two conjoined newborns named “Jodie” and “Mary.” Mary could not survive without being connected to Jodie’s heart and lungs while Jodie could survive without being connected to Mary. Unfortunately, Jodie’s organs were expected to fail after a few weeks due to the strain of supporting both herself and Mary. The court decided that the most ethical decision was to separate Mary from Jodie so that at least Jodie would survive. But the court emphatically stated that Mary, in spite of her complete dependence on Jodie, was still a person with a right to live. The court said,

“All parties took for granted in the court below that Mary is a live person and a separate person from Jodie . . . in the face of that evidence it would be contrary to common sense and to everyone’s sensibilities to say that Mary is not alive or that there are not two separate persons.”4

A human organism gradually becomes a person over time.

This critic says that there is no precise moment when a human becomes a person, but by the time a fetus is born it obviously is a person. But this just assumes newborns are persons without giving a reason why they are persons. Once again, we need a definition of what a person is besides, “A person is who I think a person is.”

Alternative Responses

So I think I’ve shown that any defense of the claim that unborn humans are not persons will either entail that newborns are not persons, or include non-human animals as persons as well. It seems that there is no consistent way to deny the personhood of embryos and fetuses and affirm the personhood of newborn infants. As Peter Singer says,

“[P]ro-life groups are right about one thing: the location of the baby inside or outside the womb cannot make such a crucial moral difference. We cannot coherently hold that it is all right to kill a fetus a week before birth, but as soon as the baby is born everything must be done to keep it alive.”5

But maybe there is another way pro-choice advocates could defend abortion without defending infanticide. One way would be to concede that newborns are not persons but claim that there are other reasons that make infanticide immoral.

I’ll confess though that I haven’t found those reasons to be very persuasive (e.g. our species couldn’t survive if we killed too many babies, infanticide might make us heartless, etc.). They seem to be very “ad-hoc,” or cited just to support people’s emotional revulsion to infanticide. Due to space issues I will probably comment on them in a future post if the discussion warrants it.

The other way would be to use what are called bodily rights arguments in defense of abortion. While infants live outside of a woman’s body, fetuses live inside of it—which could be a morally relevant difference between the two cases. Even if the fetus is a person, perhaps abortion can still be justified based on the woman’s right to control her body.

I’ll take a look at those arguments on Wednesday in Part 2 of this series.
(Image credit: Fast News Release)


  1. David Boonin, A Defense of Abortion (Cambridge University Press: Cambridge, 2003) 20. I will admit I think that Boonin’s “desire-based” argument against fetal personhood is the best attempt at defining abortion to exclude fetuses, exclude non-human animals and include newborns, but due to the length of this post I have not included it. I am willing to do that in a future post.
  2. Peter Singer, Practical Ethics, 2nd ed. (Cambridge: Cambridge University Press, 1993), 73. And before you link to it, I’m familiar with Ophelia Benson’s post on this quote. Singer goes on to say, “ . . . and the same is true of the most profoundly and irreparably intellectually disabled human being, even of an anencephalic infant – that is, an infant that, as a result of a defect in the formation of the neural tube, has no brain.” But this doesn’t refute my point. Boonin and Singer admit that any human organism, even a dying anencephalic one (or an adult who blew the top of his head off with a shotgun) are human organisms or biological human beings. The question of whether they are persons is a different issue.
  3. Mary Anne Warren, “On the Moral and Legal Status of Abortion” The Monist, 57, no. 4, 1973.
  4. In Re A (Children) (Conjoined Twins: Surgical Separation) [2001] Fam 147, Court of Appeal, Ward, Brooke And Robert Walker LJJ, Page 182. PDF)
  5. Peter Singer and Helen Kuhse,“On Letting Handicapped Infants Die,” in The Right Thing to Do: Basic Readings in Moral Philosophy ed. James Rachels (New York: Random House, 1989), 146.
Trent Horn

Written by

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.

Note: Our goal is to cultivate serious and respectful dialogue. While it's OK to disagree—even encouraged!—any snarky, offensive, or off-topic comments will be deleted. Before commenting please read the Commenting Rules and Tips. If you're having trouble commenting, read the Commenting Instructions.