In her still-widely-read 1971 article, "A Defense of Abortion," Judith Jarvis Thomson sets up a thought experiment known as "The Famous Violinist Problem" to argue that abortion ought to be morally justified when a pregnancy arises out of sexual assault:

"You wake up in the morning and find yourself back to back in bed with a ...famous unconscious violinist. He has been found to have a fatal kidney ailment, and the Society of Music Lovers has canvassed all the available medical records and found that you alone have the right blood type to help. They have therefore kidnapped you, and last night the violinist's circulatory system was plugged into yours, so that your kidneys can be used to extract poisons from his blood as well as your own.... To unplug you would be to kill him. But never mind, it's only for nine months. By then he will have recovered from his ailment, and can safely be unplugged from you."

Most people would share the intuition that they should be able to unplug themselves from the violinist, since they didn't consent to being hooked up in the first place. Others would suggest an analogy with becoming pregnant from rape, so the mother could "unplug" herself from the child by abortion.

At least two serious problems, however, exist with this analogy.

First, the famous violinist is not a good parallel for the child conceived by sexual assault. The violinist in Thomson's thought experiment is basically a stranger to us. But the child conceived in rape is not, properly speaking, a stranger at all, and the analogy should probably be corrected to indicate this: "When the woman wakes up, she finds herself connected to a prodigy violinist who also happens to be her 12 year old son." In such a scenario, she would far more easily admit an obligation to remain attached to him, even for an extended period of time. Following a rape that results in pregnancy, a woman likewise finds herself connected to her own progeny, her own child in utero, with similar natural moral obligations to nurture and care for her own flesh and blood.

The second problem with Thomson's analogy is that abortion is not like "unplugging" a tube connecting one person to another, and allowing the dependent individual to expire from a condition like kidney failure. Instead, abortion invokes various surgical and obstetrical procedures that directly end the life of, and even dismember, the in utero child.

Norma McCorvey, the former "Jane Roe" of the Roe vs. Wade Supreme Court decision, herself once worked in an abortion clinic and later described what happened there:

"When a later abortion was performed, workers had to piece the baby back together, and every major part -- head, torso, two legs, and two arms -- had to be accounted for. One of our little jokes at the clinic was, "If you ever want to humble a doctor, hide a leg so he thinks he has to go back in." Please understand, these were not abnormal, uncaring women working with me at the clinic. We were just involved in a bloody, dehumanizing business, all of us for our own reasons. Whether we were justifying our past advocacy (as I was), justifying a previous abortion (as many were) or whatever, we were just trying to cope -- and if we couldn't laugh at what was going on, I think our minds would have snapped."

McCorvey's comments remind us that abortion is essentially a violent and deadly act, not a euphemistic "unhooking" or "separating" of mother and child. Thus we might wish to modify Thomson's analogy once again in order to maintain parallelism: "A woman wakes up in the morning and finds herself attached to a violinist. To free herself from any further involvement with him, she asks a doctor to come in with a knife and to dismember the renowned musician." The absolute wrongness of such direct killing would remain beyond dispute, as would the wrongness of any direct killing actions by a raped woman directed against her unborn son because of the sins of his father.

In reflecting on the specifics of "The Famous Violinist Problem," we begin to appreciate the importance of never subjecting an innocent third party, whether a musician or an in utero child, to direct lethal harm simply because they find themselves in a state of radical dependence upon another human being. Although we aren't obligated to use extreme or extraordinary measures to try to save the violinist in Thomson's thought experiment, we shouldn't make the error of supposing that the state of pregnancy itself is somehow extraordinary or extreme, even in the tragic case of sexual assault, given that it objectively embodies the natural and familial line of duty to care for our own offspring.

Father Tadeusz Pacholczyk, Ph.D. earned his doctorate in neuroscience from Yale and did post-doctoral work at Harvard. He is a priest of the diocese of Fall River and serves as the Director of Education at The National Catholic Bioethics Center in Philadelphia. (www.ncbcenter.org).