Imagine you wake up one day and find yourself in a hospital bed. You have no idea how you got there, and there are cords running out of your body and into the body of a person who’s lying back to back with you on the bed. You understandably start to freak out a little. A doctor rushes in and explains: “It’s okay, you’re safe. Here’s what happened. That man on the hospital bed with you is a world-famous violinist who has a rare, typically deadly disease. He needs to be hooked up to someone’s kidneys so they can filter his blood, and it turns out you’re the only match in the world. So the Society of Music Lovers, which is obsessed with this guy and really doesn’t want him to die, kidnapped you, brought you here, and hooked you up.”

Estimated reading time: 7 minutes
“I’m so sorry that they did that to you—that was super messed up, and if I’d known, I wouldn’t have let it happen. But now you’re kind of stuck. Because you see, if you unplug from the violinist, he’ll die. So it seems like that would be wrong. But don’t worry, if you lie here hooked up to him for nine months, you’ll both be able to unplug safely and go on your merry way.”
The Violinist Argument
If you haven’t heard that story before, it was created by a philosopher named Judith Jarvis Thomson in her 1971 paper “A Defense of Abortion.” She argues—and most pro-life and pro-choice people agree—that it should be legal to unplug from the violinist in her thought experiment scenario. And she uses that intuition to argue that abortion should be legal too. She says that having an abortion is like unplugging from the violinist: You stop using your body to help a person whom you never agreed to help in the first place, and as a result, they die. Since the two cases are similar in morally relevant respects, Thomson argues, abortion should be legal just like unplugging from the violinist should be legal.
Importantly, this is a bodily autonomy argument. It assumes, at least for the sake of argument, that human fetuses are people like you and me with an equal right to be protected from violence. It argues that abortion should still be legal, even if fetuses are people, because of the woman’s rights to her own body—in this case, particularly her right to refuse to use her body to help people.
We at ERI have talked a lot about how to respond to the violinist argument in conversations with pro-choice people. But there’s another point related to it that I’ve heard both pro-life and pro-choice people make in different scenarios: the worry that it’s philosophically “cheating” to use an implausible thought experiment to support your point. Sometimes pro-lifers look at the violinist and say, “But that would never actually happen. There’s no disease where you’d need to be hooked up to one particular person for nine months—that’s ridiculous!” They feel like the fact that the thought experiment scenario could never actually happen means it’s not applicable in a dialogue about whether abortion should be legal, since it’s not even real. And I’ve heard some pro-choice people say exactly the same things about implausible pro-life thought experiments. (I think the weirdest thought experiment we use at ERI involves physiologically impenetrable uteruses.)
Why Thought Experiments are Kosher
We at ERI have often responded to people raising this concern by pointing out that their side (whether they’re pro-life or pro-choice) uses weird, implausible thought experiments too. We’ve also pointed out that it’s widely accepted for philosophers to use weird thought experiments to make arguments about any number of topics, not just abortion. Philosophers, pro-lifers, and pro-choice people all clearly operate as though weird and implausible thought experiments are fine to appeal to and need to be taken seriously as arguments.
But I always wanted to be able to articulate to myself exactly why implausible thought experiments are kosher, not just appeal to authority (even legitimate authority!) to just declare them so. And I could never do it to my satisfaction. Until a couple weeks ago, when an awesome pro-life intern at a speaking gig I was at in Michigan asked me about thought experiments, and the answer finally clicked in my brain after literally years of wondering about it.

We were talking about the Equal Rights Argument and what makes us (and human fetuses) “persons”—entities with an equal right to be protected from violence. I said that being a biological human can’t be what makes us persons, because of Reepicheep. If you don’t know who Reepicheep is, he’s a valiant, chivalrous knight of Narnia, who happens to be a talking mouse. (Incidentally, if you don’t know who Reepicheep is, you really need to read (or reread) The Chronicles of Narnia.) Reepicheep isn’t a biological person, and yet clearly has the same equal right to be protected from violence that you and I have. So, I argued, being biologically human can’t be what gives us our equal rights.
A student pushed back and asked, “But why does that matter? Obviously Reepicheep’s not a person—he doesn’t exist!” She was pulling on the same thread that bugs people about the violinist (and many other pro-life and pro-choice thought experiments)—it feels really weird to draw conclusions about something in real life, like abortion, based on something that not only has never happened but definitely will never happen, like talking mice.
After a solid minute of stuttering and talking around it, I finally landed on the explanation I’d been looking for. I said, “Reepicheep doesn’t exist, so he’s not a person. But if we define that what gives us personhood is being biologically human, that wouldn’t just mean that Reepicheep isn’t a person (because he doesn’t exist). It would mean that Reepicheep wouldn’t be a person even if he did exist. And that’s not true—in the crazy alternate universe where Reepicheep really exists, intentionally killing him would be just as much a murder as killing a human, rather than pest control like killing an ordinary mouse.” So “Biological humanness is what defines personhood” implies something false—namely, “If Reepicheep existed, he wouldn’t be a person.” Claims that imply something false have to be false. So it’s false that biological humanness is what defines personhood.
Bringing it Back to the Violinist
In the same way, Thomson is arguing: “If you say that refusing to continue helping someone with your body (like by having an abortion) shouldn’t be legal, that means that if you ever actually were hooked up to the violinist, refusing to continue helping him with your body shouldn’t be legal either. But that’s false: If you ever were hooked up to the violinist, unplugging from him should be legal. So your pro-life claim implies something false. So your claim must be false.”
Now to be clear, I don’t think the violinist argument works—I think the obligation to not kill people argument is extremely successful against it. But I think the violinist argument is a philosophically kosher move for pro-choice people to make. I think it doesn’t ultimately work, but I think we have to prove that it doesn’t work by actually engaging with the details of the argument. We can’t successfully just dismiss it off the bat because it’s an implausible thought experiment. Implausible thought experiments can still prove things about real-world claims, because real-world claims have implications about what would be true if the thought experiment were real.
So if you ever need to convince a pro-choice person that it’s legitimate for pro-lifers to use weird thought experiments (or convince a pro-lifer that it’s legitimate for pro-choice people to use weird thought experiments), or if you’re wondering about it yourself, think about it this way: If a claim implies something false, then that claim must be false. And the claims we make about reality have implications not just about what is true, but about what would be true if a thought experiment were real. The claim “biological humanness is the thing that gives personhood: if you’re a biological human, you’re a person, and if you’re not a biological human, you aren’t a person” doesn’t technically have false implications about whether Reepicheep is a person—he’s not a person, because he doesn’t exist. But the claim does have false implications about whether Reepicheep would be a person if he did exist. And if a claim has any false implications, even false implications of the form “If x were real, y would happen,” that claim can’t be true. So it’s legitimate to use even a weird thought experiment about x to disprove a claim about reality.
The post Is This Pro-Choice Thought Experiment Cheating? originally appeared at the Equal Rights Institute blog. Subscribe to our email list with the form below and get a FREE gift. Click here to learn more about our pro-life apologetics course, “Equipped for Life: A Fresh Approach to Conversations About Abortion.”