We all recognize that if such a thing would be imposed upon you, it would be unjust. A person, no matter how valuable or famous, does not have the right to use your body if you don't want them to. The argument extrapolates from this conclusion that abortion, then, is legitimate, as it is merely the refusal to allow another person to use one's body for their sustenance (see the full argument here).
1. Responsibility vs. Altruism: A violinist is vastly different than one's own child. The violinist didn't require life support because of your actions. Your unborn child does. A potential consequence (or blessing) of sex is that a child may be brought into being. This is common knowledge. One takes upon themselves this responsibility when engaging in sex. And if a child is brought into existence through your actions, you are responsible for them. (I am of course excluding the minority of abortions due to rape here).
I was once dialoguing with an individual about this and their response was that pro-lifers are always so narrow. He likened the consequence and responsibility of pregnancy to a car accident. He said that the pro-life position was like telling someone that if they were injured after taking on the responsibility for driving, then you were just going to let them bleed out. If they understood an accident was possible yet still choose to drive, then their injuries are their problem. He was essentially saying that getting pregnant is like getting injured in a car accident, and withholding abortion is like withholding care to the injured.
Such an analogy completely misses the true relationship of a parent and child. Abortion is more like choosing to drive, hitting someone else, and then failing to tend to the needs of the injured. Abortion is like hitting someone and then allowing them to die, refusing to call 911, or putting a bullet in their head. We all recognize that when your actions affect someone else - malicious, negligent, or completely accidental - you have a responsibility for their well-being. Understanding this is important because pro-choice individuals will sometimes try to argue that consent is at the core of the argument. Just as your consent would be required to hook the violinist up to you - and your continued consent required to sustain that connection - so a mother's consent is required throughout pregnancy. Requiring consent misses the point that the mother and father are responsible for putting the child in its condition. It would be like arguing that if I hit someone, the paramedics would need my consent to save their lives. What if I don't want the responsibility of paying for medical bills? Do I have the right to tell the paramedics to let the injured die? Helping someone whose condition I'm responsible for creating isn't altruism, it's responsibility. I'm required to seek their well-being because their being in such a state is a result of my actions. I will have to pay money (usually the insurance company does this as your representative). I may face legal consequences. That makes sense in the real world with everything else, so why not with pregnancy?
The violinist is nothing like an unborn child because you are not responsible for the violinist's well-being. Your act did not put him there.
2. The Intuition isn't Intuitive: Almost everyone recognizes that bodily autonomy is valid, so long as it doesn't impose on others. It's illegal in most places to walk around naked - even in your own yard (depending on if you live in a visible area). It's illegal for you to use illicit drugs in your own body. We all understand that there are certain things you can't do with your own body.
Maybe you're a libertarian and don't agree with my above examples, so let's dig further. We can see through common sense that when we couple the idea of a relational responsibility with the fact that you don't have complete bodily autonomy, we have another knock against the violinist argument. If a mother doesn't have formula available, is she required to breast feed her child or can she let her child starve? We would all be appalled at the inhumanity of a mother who is capable of nursing who refuses to use her breasts to feed her child. As a father, do I have to pick my child up and change his diaper? What if I don't want to take the chance of getting poop on my hand? If I'd rather do my own thing, can I just let my child lie in his crib 24 hours a day? Do I ever have to use my body or risk injuring my bad back to pick him up, bathe him, etc? Children take time (which involves my body, because I'm a spatial being), money (which I am paid for using my body to accomplish work), and the list goes on. Why can't I refuse to use my body for my child if I have bodily autonomy? Because we all recognize that bodily autonomy, while generally true, isn't the only consideration.
3. Unjustified Killing: I wrote about the legitimacy of taking life in a different section. The conclusion was that actively killing another person is only justified in the minds of most if imminent danger to one's life or serious well-being is in view. Most pregnancies don't even come close to fitting this justification, as most women deliver just fine. There is rarely a reason to think a mother's life is in danger. Beyond the lack of threat by the unborn, there is also a huge distinction between refusing to connect someone else to you for life support and actively killing (stabbing, burning, and brain suctioning) an individual whose condition you're responsible for creating. While we could argue about what the most moral thing to do would be altruistically in the case of the violinist, the ambiguity there doesn't make the active killing in abortion ambiguous at all.
4. Inconsistency: While this may not apply to all in the pro-choice camp, it certainly applies to most. The Violinist Argument is often evoked because proponents understand that a fetus is both living and human. They therefore acknowledge the humanity of an embryo and say that the reason it can be destroyed is due to bodily autonomy. However, they tip their hands when they advocate things like stem cell research (which most do). If proponents of the Violinist Argument acknowledge the humanity of embryos, how can they advocate IVF over-fertilization which creates life that will then knowingly be destroyed, or embryonic stem cell research, which treats living human beings as objects for research, and purposefully destroys them? It's one thing to argue that bodily autonomy legitimizes the killing of an embryo and allow such a thing, but how can you then create embryos - acknowledged to be human life - for the purpose of research and destruction?
5. Other arguments: I am linking another article you may find helpful for more arguments. I didn't include more because I find them too filled with presuppositions or I disagree with the conclusions. Nevertheless, someone else may find them helpful. "Unstringing the Violinist."
6. If you'd like to check out another argument I'm working on, but am not yet sure of, you can see A Strange Rebuttal Against the Violinist Argument for Abortion here.
1. The Foundational Question: What is killed in abortion?
2. How to Determine Value and Rights: What quality and types of qualities confer rights and value to an individual?
3. Justified Reasons for Taking Human Life: What justifies the taking of human life?
4. Unjustified Reasons for Taking Life: What reasons fail to justify the taking of human life?
5. Bad Christian Arguments and Witness: Common pro-life/Christian arguments and actions which can undermine the pro-life position.
6. Counterrebuttals: A response to significant objections to the pro-life arguments.