Lecture 4 — Abortion
Part A: Four Arguments in Standard Form
0.1 You Wake Up Connected
You wake up in a hospital bed. In the bed beside you is a famous, unconscious violinist. The Society of Music Lovers has discovered that you alone have the right blood type to keep his failing kidneys filtering. Overnight they kidnapped you, sedated you, and plugged his circulatory system into yours. The hospital director apologizes. The violinist will die if you unplug. He needs you for nine months.
Write or discuss:
- Are you morally required to stay plugged in for nine months?
- If you unplug, have you killed him — or simply refused to save him?
- Where, exactly, does this scenario stop resembling a pregnancy?
This is Judith Jarvis Thomson’s 1971 case. We reconstruct it as an explicit argument later in the chapter.
0.2 After You’ve Discussed
- A right to life is not automatically a right to use someone else’s body. These are two different rights, and people slide between them.
- There is a moral difference between “killing” and “letting die.” Where you draw that line will decide many other cases in this course.
0.3 Today
By the end of Part A, you will be able to:
- Tell validity from soundness, and spot the equivocation on “human” that runs through abortion arguments
- State Don Marquis’s future-like-ours argument and the strongest objection to it
- Apply Mary Anne Warren’s five marks of personhood to borderline cases (zygote, newborn, adult with advanced dementia, dolphin, AI)
- Reconstruct Judith Jarvis Thomson’s violinist case as a formal argument and locate at least two disanalogies critics press against it
- Explain how Rosalind Hursthouse’s virtue-ethics approach reframes the abortion question away from the status of the fetus
- Identify, for any abortion argument, the load-bearing premise — the one premise the disagreement actually turns on
0.4 Standard Form, Recapped
Earlier in the course we treated an argument as premises plus a conclusion. Today we write them in standard form: numbered premises, then the conclusion.
- An argument is valid when the conclusion follows: if the premises were true, the conclusion would have to be.
- It is sound when it is valid and every premise is actually true.
- Most serious abortion arguments are valid. The fight is over whether one premise is true, so the skill is finding that premise.
0.5 The Equivocation Trap
The word “human” has two very different senses, and arguments about abortion routinely slide between them without anyone noticing.
Biological sense. “Human” = a living member of the species Homo sapiens. A zygote, a fingernail clipping, a tumor of human tissue — all human in this sense.
Moral sense. “Human” = a being with the kind of mental and moral life that grounds a right to life. An adult patient, plausibly a newborn — human in this sense.
The trap. “The fetus is human” is true in the biological sense — but the conclusion “it is wrong to kill the fetus” only follows if “human” means the moral sense. Sliding between the two senses inside a single argument is the fallacy of equivocation, and it is the single most common error in abortion debates on both sides.
0.6 Two Traps to Watch For — Begging the Question
An argument begs the question when one of its premises already assumes the very conclusion it is trying to establish. The argument doesn’t prove anything; it just restates.
Anti-abortion version:
- Abortion is the murder of an innocent person.
- Murder is wrong.
- ∴ Abortion is wrong.
The word “murder” has already done all the work — it means wrongful killing of a person. Premise 1 is the conclusion.
Pro-choice version:
- The fetus is just a clump of tissue in the woman’s body.
- People can do as they wish with tissue in their own bodies.
- ∴ Abortion is permissible.
“Just a clump of tissue” assumes the fetus has no moral status — which is the very point in dispute.
Once you can see equivocation and question-begging, you hear them everywhere. These two are worth the effort: they transfer to every chapter that follows.
0.7 Activity — Reconstruct It
Here is a passage in the style philosophers actually write in. Pull it apart into standard form on paper or in a text box.
“Look — every one of us was once a fetus. If our mothers had ended those pregnancies, none of us would be here to argue about it. The fetus you are talking about already has a future ahead of it, the same kind of future you and I value in our own lives. To cut that future off is no different in principle from cutting yours off. That is why abortion is wrong.”
Write or discuss:
- What is the conclusion of this passage? (One sentence.)
- What are the premises — the claims the author needs you to accept to get to that conclusion? (Number them 1, 2, 3.)
- Which premise do you find least secure, and why?
This is a paraphrase of Marquis, not his exact words. We formalize it carefully in the next section — you will see it again.
0.8 A Short Biological Primer
- A zygote is the single cell formed at fertilization, when sperm and egg fuse.
- An embryo is the developing organism from implantation (~2 weeks) through the eighth week, when the major organ systems first form.
- A fetus is the developing human from the ninth week of gestation until birth.
- Viability is the point at which a fetus could plausibly survive outside the womb with intensive medical support — currently around 22–24 weeks.
Gestational age vs. fertilization age. Clinicians count pregnancy from the first day of the last menstrual period (LMP), about two weeks before fertilization. So a “12-week pregnancy” describes a roughly 10-week-old embryo or early fetus.
0.9 Timeline of Fetal Development
Adapted from clinically standard developmental timelines.
0.10 Trimester at a Glance — What Patients Are Actually Experiencing
| Trimester | Weeks (LMP) | What is developing | What care typically looks like |
|---|---|---|---|
| First | 0–13 | Implantation; neural tube closes (~wk 4); cardiac activity detectable (~wk 6); limb buds; basic organ systems | Confirmation of pregnancy, prenatal vitamins, first ultrasound, ~80% of US abortions occur here |
| Second | 14–27 | Quickening (felt movement, ~16–22 wk); anatomy scan (~20 wk); viability threshold approaches (~22–24 wk) | Anatomy ultrasound; diagnostic testing for fetal anomalies; most pregnancy losses here are not elective |
| Third | 28–40 | Rapid weight gain; lung maturation; final neurological wiring; positioning for birth | Frequent prenatal visits; delivery planning; elective abortion is extremely rare and almost always for fetal anomaly or maternal life |
Why this matters for nursing. Patients use clinical week counts, not fertilization counts. A “six-week pregnancy” is a roughly four-week-old embryo, smaller than a grain of rice. Some recent state laws are written to take effect at clinical week 6 — before many people realize they are pregnant.
0.11 How Abortion Is Actually Performed
Medication abortion (up to ~10–11 wk; ~63% of US abortions in 2023). Often at home.
- Mifepristone blocks progesterone, ending the pregnancy.
- Misoprostol, taken 24–48 hours later, causes the uterus to contract and expel the pregnancy.
Procedural abortion in clinics (any gestational age; ~37% of US abortions).
- Aspiration / vacuum (most first-trimester procedures): the uterine contents are removed through a thin tube; takes ~5–10 minutes.
- Dilation and evacuation (D&E) (second trimester): cervix dilated; instruments and suction used to empty the uterus.
The pre-2022 picture is shifting. After Dobbs (2022), state-by-state law has become the dominant variable in what is actually available to a given patient. Part B picks this up.
0.12 Who Actually Has Abortions
- About 1 in 4 US women will have an abortion by age 45.
- About 60% of those obtaining abortions are already mothers.
- The typical patient is in her 20s, low-income, and identifies as Christian.
- The most-cited reasons are economic instability, timing, and responsibilities to existing children.
- About 80% of US abortions occur in the first trimester; under 1% occur after 21 weeks, almost always for severe fetal anomaly or maternal life.
Public images of abortion often imagine a single, young, childless patient making a quick decision. The data describe a different population: women already raising children, deciding from inside the constraints of an existing family.
Figures from Guttmacher Institute and CDC Abortion Surveillance, 2020–2023.
0.13 What Makes Something Matter Morally?
To have moral status is to count, in your own right, in moral reasoning. Each candidate criterion gives a different verdict on the early fetus.
| Criterion | What it means | Early fetus? | Lines up with |
|---|---|---|---|
| Biological humanity | A living member of Homo sapiens | Yes | The conservative right-to-life argument |
| Potentiality | Will become a person if not killed | Yes | Marquis |
| Sentience | Able to feel pleasure and pain | No, until ~24 weeks | Most pro-choice arguments |
| Personhood | Consciousness, reasoning, self-awareness | No | Warren |
1 Four Arguments
1.1 Argument 1 — The Future-Like-Ours Argument
Marquis: Abortion Deprives a Fetus of a Future Like Ours
Don Marquis, “Why Abortion Is Immoral” (1989)
- What makes killing an adult human being seriously wrong is that it deprives the victim of all the experiences, projects, activities, and relationships that would otherwise have made up their future.
- Whatever it is that makes killing wrong in adults is what makes it wrong in any case.
- A standard human fetus, if not killed, has a future containing experiences, projects, activities, and relationships of the same general kind — a future like ours.
- Therefore, killing a standard human fetus is seriously wrong, for the same reason killing an adult is.
1.2 The Strange Company Marquis’s Principle Keeps
Marquis’s principle — killing is wrong when it deprives a being of a valuable future — has consequences that surprise people on both sides of the debate.
- Contraception is not wrong. There is no being yet to be deprived; sperm + egg = no subject of a future.
- Removing life support from a permanently comatose patient may not be wrong — there is no valuable future to lose.
- Abortion of an anencephalic fetus (no brain development possible) is permissible — no future of the relevant kind.
- Most abortions for socioeconomic reasons are seriously wrong — the fetus’s future doesn’t care about the mother’s circumstances.
- Abortion for fetal Down syndrome is wrong — those futures are valuable too.
- Killing many animals may be wrong if they have futures of value (Marquis himself is cautious here).
1.3 Marquis: Unpacking “a Future Like Ours”
Marquis’s argument is unusual: it does not depend on the fetus being a “person” right now, or on having a soul, or on a heartbeat. It depends only on the fetus having a valuable future.
That move has two consequences worth noticing:
- It explains why killing a temporarily unconscious adult is wrong: their future is still there, waiting for them, even though they are not currently conscious. The same logic, Marquis says, covers the fetus.
- It does not automatically cover a permanently comatose patient, or a fertilized egg in a clinic freezer that no one will implant — because those entities arguably have no future to be deprived of.
The premise doing the heavy lifting is P3 — that the fetus’s future is “of the same general kind” as yours. That is where critics push.
1.4 Objection to Marquis
The Identity Objection (targets P3)
A common reply in the secondary literature (Harman 2025, sec. 2.2)
- For losing a future to be a harm to me, the future being lost must be mine — it must belong to a continuous psychological subject who can be deprived.
- A zygote or early embryo has no psychological life at all — no memories, no plans, no point of view from which a future could be “lost.”
- So the early embryo is not the subject of any future; talk of “its future” is more like talk of the future of a sperm-and-egg pair before they meet.
- Therefore, even granting Marquis’s general principle, it does not yet show that early abortion deprives anyone of a future.
1.5 Activity — Whose Future Counts?
Marquis’s argument stands or falls on who counts as having “a future like ours.”
Write or discuss. For each entity below, does Marquis’s argument apply? Why or why not?
- A 26-year-old in a coma expected to wake up in three weeks.
- A 70-year-old with advanced Alzheimer’s, no memory of yesterday, who will likely die within the year.
- A 6-week embryo conceived through IVF that the couple has decided not to implant.
- A frozen embryo that will be donated for stem-cell research with no chance of implantation.
1.6 Argument 2 — The Personhood Argument
Warren: A Fetus Is Not Yet a Person
Mary Anne Warren, “On the Moral and Legal Status of Abortion” (1973)
- The right to life belongs to persons — beings with a recognizable mental and moral life — not to every member of the biological species Homo sapiens.
- To be a person in this morally relevant sense is to possess (some significant set of) consciousness, reasoning, self-motivated activity, the capacity to communicate, and self-awareness.
- A fetus, at any stage of development, possesses none of these traits to any meaningful degree.
- Therefore, a fetus is not a person and does not yet have the right to life that persons have.
1.7 Warren, in Her Own Words
“A fetus, even a fully developed one, is considerably less personlike than is the average mature mammal, indeed the average fish. And I think that a rational person must conclude that if the right to life of a fetus is to be based upon its resemblance to a person, then it cannot be said to have any more right to life then, let us say, a newborn guppy.”
Mary Anne Warren, “On the Moral and Legal Status of Abortion” (1973), §III.
1.8 Warren: The Five Criteria
Warren argues that a fetus might have some moral value, but is not yet a person, since it lacks most of the following:
| Criterion | Plain-language gloss |
|---|---|
| Consciousness | Aware of things; can feel pain or pleasure |
| Reasoning | Can solve new and reasonably complex problems |
| Self-motivated activity | Acts on its own, not just by reflex or external cue |
| Capacity to communicate | Can convey many kinds of messages, on many topics |
| Self-awareness | Has a concept of itself as a continuing subject |
Critics argue that newborn infants also fail most of these tests, yet killing them is plainly murder.
1.9 Objection to Warren
The Infanticide Objection (targets P2 and P3)
A standard reply, pressed in many forms since Warren’s paper
- A newborn infant lacks all five of Warren’s marks of personhood to any greater degree than a third-trimester fetus does.
- So if Warren’s criteria are correct, killing a newborn is not killing a person, and is therefore not a violation of the right to life.
- But killing a newborn is obviously a grave moral wrong.
- Therefore, either Warren’s criteria are wrong, or Warren’s account is missing something — full moral status cannot rest on present psychological capacities alone.
Warren’s reply (1982): infanticide is wrong because others want and can care for the infant. That moves the moral weight off the infant and onto social facts.
1.10 Activity — Personhood Scoreboard
Score each entity on each of Warren’s five criteria using 0 (none), ½ (some), or 1 (clearly present). Then write a one-sentence verdict: is this entity a person, on Warren’s account?
| Entity | Conscious | Reasons | Self-motivated | Communicates | Self-aware |
|---|---|---|---|---|---|
| Zygote (day 1) | |||||
| Fetus, 24 weeks | |||||
| Newborn infant | |||||
| Adult dolphin | |||||
| Adult with advanced dementia | |||||
| Large language model (ChatGPT) |
Write or discuss. Which row was hardest? What does that suggest about Warren’s criteria?
1.11 Argument 3 — The Bodily Autonomy Argument
Thomson: A Right to Life Is Not a Right to Use Another’s Body
Judith Jarvis Thomson, “A Defense of Abortion” (1971)
- Even granting that the fetus is a person with a full right to life, a right to life does not include the right to use another person’s body without that person’s ongoing consent.
- A pregnant person who has not consented to the pregnancy (e.g., rape, contraceptive failure) has not granted the fetus the use of her body.
- Withdrawing the use of one’s body from another is not unjust killing; it is the refusal to extend an extraordinary form of aid.
- Therefore, in at least some cases, abortion does not violate any right of the fetus and is morally permissible.
1.12 Thomson, in Her Own Words
“I propose, then, that we grant that the fetus is a person from the moment of conception.… I am inclined to think also that we shall probably have to agree that the fetus has already become a human person well before birth.… [But] having a right to life does not guarantee having either a right to be given the use of or a right to be allowed continued use of another person’s body — even if one needs it for life itself.”
Judith Jarvis Thomson, “A Defense of Abortion” (1971), §§1, 4.
1.13 Thomson: The Move That Shocked Everyone
The brilliance of Thomson’s argument is the phrase “even granting” in premise 1. Nearly every prior debate had assumed that if the fetus is a person, abortion is obviously wrong. Thomson said: fine, grant it — and abortion is still sometimes permissible.
This reframes the entire debate. The question is no longer only “Is the fetus a person?” It becomes: “What does a right to life actually entitle you to?”
A right to life is narrower than people assume. Thomson points out that you cannot, for instance, demand that Henry Fonda fly across the country to put his cool hand on your fevered brow — even if it is the only thing that will save your life. Your right to life does not give you a right to whatever you need to keep living.
1.14 Objection to Thomson
The Responsibility Objection (targets P2)
A standard reply (Harman 2025, sec. 1.2)
- If you voluntarily engage in an activity knowing it has a foreseeable chance of producing a dependent being, you have implicitly taken on responsibility for that being.
- Consensual sex is such an activity, even with contraception: pregnancy is a known, foreseeable possibility.
- Therefore, in the typical case of pregnancy from consensual sex, P2 is false — the pregnant person has implicitly granted the fetus the use of her body, the way the violinist analogy does not assume.
- So Thomson’s argument, even if sound in the rape case, does not generalize to most actual abortions.
1.15 Activity — Disanalogy Hunt
An analogy is only as strong as its weakest joint. Thomson’s case is built on a structural likeness between being plugged into the violinist and being pregnant.
Write or discuss. List three concrete disanalogies between Thomson’s violinist case and a typical pregnancy. For each one, answer:
- What is the difference?
- Does the difference make the violinist case more like an easy case (where unplugging seems obviously fine) or less like an easy case?
- Does the difference, in your judgment, defeat Thomson’s argument, or only limit the range of pregnancies it covers?
1.16 Argument 4 — The Virtue-Ethics Argument
Hursthouse: The Question Is About Character, Not Status
Rosalind Hursthouse, “Virtue Theory and Abortion” (1991)
- An action is right if and only if it is what a fully virtuous person (honest, courageous, just, practically wise) would characteristically do in the circumstances.
- Whether having an abortion is what a virtuous person would do depends on the agent’s motives, circumstances, and what the choice expresses about her character.
- Some abortions plainly express vices — callousness, vanity, irresponsibility, refusal to face the seriousness of what is happening.
- Other abortions plainly express virtues — clear-eyed acknowledgment of a serious matter, care for existing children or dependents, honesty about one’s own limits.
- Therefore, whether a particular abortion is morally right or wrong is not settled by the metaphysical status of the fetus alone; it turns on the character and circumstances of the choice.
1.17 Hursthouse, in Her Own Words
“To think of abortion as nothing but the killing of something that does not matter, or as nothing but the exercise of some right or rights one has, or as the incidental means to some desirable state of affairs, is to do something callous and light-minded, the sort of thing that no virtuous and wise person would do. It is to have the wrong attitude not only to fetuses, but more generally to human life and death, parenthood, and family relationships.”
Rosalind Hursthouse, “Virtue Theory and Abortion” (1991), §III.
1.18 Hursthouse: What a Virtuous Person Notices
Hursthouse’s move is to change the subject of the question. Marquis, Warren, and Thomson all ask: what kind of thing is the fetus, and what follows? Hursthouse asks: what kind of person decides this way, in these circumstances?
Two things she insists on. First, even if abortion is sometimes permissible, the loss of a potential human life is a grave matter — to treat it as trivial is itself a moral failing. Second, character is judged not just on the act but on the motivations and attitudes around it: the same outward act, done flippantly or done with sorrow, is not morally the same.
1.19 Objection to Hursthouse
The Action-Guidance Objection (targets P1)
A standard line of criticism of virtue ethics generally
- A pregnant person facing this decision needs guidance: a way to tell what to do now, not a description of what some idealized virtuous person would do.
- “Do what a virtuous person would do” is unhelpful — if I knew what the virtuous person would do, I would not need the theory; and if I do not know, the theory does not tell me.
- Hursthouse offers vocabulary (callous, light-minded, courageous) rather than rules, but two thoughtful people can apply that vocabulary to the same case and reach opposite verdicts.
- Therefore, virtue ethics may describe what we admire in decisions about abortion, but it does not actually guide the decision itself.
Hursthouse’s reply: no theory escapes this. Utilitarians must predict consequences they cannot know; Kantians must interpret maxims.
1.20 Activity — A Different Question
Hursthouse refuses to settle abortion at the level of the fetus’s status. Instead, she asks what the decision expresses about a person.
Write or discuss. Consider three pregnant people, each at 10 weeks, each choosing to terminate:
- A: a 16-year-old who became pregnant the first time she had sex, terrified to tell her parents, sees no way to continue school.
- B: a 32-year-old who already has two young children, is barely paying rent, and knows another child would mean none of them eat enough.
- C: a 26-year-old who would have to cancel a long-planned European vacation if she carried to term.
- On Hursthouse’s view, does her judgment of the decision differ across the three cases? Why?
- Does it differ in ways that Marquis, Warren, or Thomson could even talk about?
- Is anything important missed by Hursthouse’s focus on character?
1.21 The Landscape So Far
Four arguments, side by side, each with the premise its disagreement turns on.
| Argument | Verdict | Load-bearing premise | What you’d have to deny |
|---|---|---|---|
| Marquis (FLO) | Most abortion is seriously wrong | P3: the fetus has a future “like ours” | That a being with no current psychology is the subject of a future |
| Warren (personhood) | Early-fetus abortion is permissible | P2: personhood is defined by these five marks | That consciousness-style criteria are the right ones (also worry: infants) |
| Thomson (autonomy) | Abortion is permissible even if the fetus is a person | P3: refusing body-use is not killing | That there’s a meaningful difference between killing and refusing aid |
| Hursthouse (virtue) | “It depends” — on motives and circumstances | P1: rightness is what the virtuous person would do | That morality reduces to character and not to rules or rights |
1.22 Activity — Circle the Weakest Premise
For each of the four arguments above, name the single premise you find weakest and explain in one sentence why.
Write or discuss.
- Marquis: The premise I would push back on is __________ because __________.
- Warren: The premise I would push back on is __________ because __________.
- Thomson: The premise I would push back on is __________ because __________.
- Hursthouse: The premise I would push back on is __________ because __________.
Then: do your four “weakest” premises share something? If they do, that shared thing is your deepest commitment in this debate.
1.23 Mini-Recap
We learned a tool — standard form — and used it on four classical arguments. Marquis grounds the wrongness of abortion in a future like ours; Warren denies that the fetus is yet a person; Thomson grants personhood and still defends bodily autonomy; Hursthouse refuses to settle the question at the level of the fetus at all and looks instead to character. In Part B we ask a different question: should the law track any of these arguments?
1.24 Review Questions
Write a brief answer to each, or use them as discussion prompts.
Recall
State Marquis’s future-like-ours argument in standard form (three or four premises). Then identify the single premise that is doing the most work — and explain in one sentence why critics target it.
Apply
A patient at 11 weeks is terminating because prenatal testing revealed Tay-Sachs disease, which kills affected children in early childhood. Which of our four thinkers (Marquis, Warren, Thomson, Hursthouse) would most support her decision, and which would most resist it?
Debate
Some critics charge that Thomson’s violinist case proves too much: if it justifies abortion, it also seems to justify a parent unplugging from a sick child who depends on continued bodily aid. Is there a principled difference between the two cases? Defend your answer using the standard-form tools from today.
1.25 Key Terms
- Standard form — an argument written as numbered premises and a marked conclusion, so the inference is visible.
- Valid / sound — valid = conclusion follows from premises; sound = valid plus all premises true.
- Moral status — the property of mattering, morally, in one’s own right.
- Personhood (Warren’s sense) — having a significant set of consciousness, reasoning, self-motivated activity, communication, self-awareness.
- Future like ours (Marquis) — a future containing the kinds of experiences and projects that make adult human futures valuable.
- Bodily autonomy (Thomson) — the right to determine what may be done with and to one’s body, even when another’s life depends on it.
- Virtue ethics (Hursthouse) — the view that right action is what a fully virtuous person would characteristically do.
1.26 Further Reading
Accessible follow-ups beyond the works cited.
- Beckwith, Francis J. Defending Life: A Moral and Legal Case Against Abortion Choice. Cambridge University Press, 2007.
- Boonin, David. A Defense of Abortion. Cambridge University Press, 2003.
- Kamm, Frances M. Creation and Abortion. Oxford University Press, 1992.
- Little, Margaret Olivia. “Abortion, Intimacy, and the Duty to Gestate.” Ethical Theory and Moral Practice 2 (1999): 295–312.
- Harman, Elizabeth. “The Ethics of Abortion.” Stanford Encyclopedia of Philosophy (2025). (Harman 2025)
- Gordon, John-Stewart. “Abortion.” Internet Encyclopedia of Philosophy. (Gordon, n.d.)