The fundamental flaw in Jarvis' argument of the violinist is that it relies on the reader not to make the distinction between euthanasia and abortion. With the poor violinist, disconnecting oneself from him allows "nature to take its course". This would be a form of passive euthanasia, which many find acceptable. However, in the same situation, shooting the violinist in the head would NOT be considered acceptable.
This type of active euthanasia correlates more closely with abortion--one disrupts the course of the natural in order to kill the fetus. Because of this, the violinist example is farther removed from abortion that Jarvis pretends it is.
Her argument relies on the fact that the mother has no responsibility for the fetus. However, when does the mother have sufficient responsibility to make abortion wrong?
What about in rape/incest? Jarvis says 'no'.
What about in accidental pregnancy despite using contraceptives? Well, it's the woman's right to do with her body as she pleases, so sure, why not.
What about if the woman has normal, unprotected intercourse? Still her body.
What if the couple are trying to conceive? Better yet, what if the woman has in vitro fertilization? Has she taken enough responsibility yet, or is it still okay for her to have an abortion?
Jarvis also likens the fetus as to being an 'attacker' and abortion as being the woman's ability to defend herself from it. This turns the fetus from being helpless, completely dependent on the woman, into an oppressor who harms the woman carrying it. In this vein of thought, the fetus becomes nothing more than a parasite that leeches off of the body of the woman, and few have any issue with exterminating parasites.
To equate the fetus to a parasite is inexcusable. It is simply wrong. To declare a large portion of the process of reproduction as parasitism is...just wrong.
From a strictly biological sense, the fetus is a parasite. This is true. It leeches nutrients from the mother and causes her great discomfort in later stages of pregnancy.
However.
From a strictly biological sense, an infant is a parasite. It suckles from the mother, steals time and energy from her, and gives nothing in returns, save for its existence. Thus, an infant should be allowed to be exterminated with this school of thought.
As for the arguments that a fetus is not a human, that it does not share the basic characteristics of qualifying as human, one must realize that humanity is not some equation that can be formulated.
Let us say that there is a fox one meets upon the road. One is hopelessly lost, and the fox notices this. He sits up, asks one about one's dilemma, and gives one directions to the nearest town. He also invites one over for supper.
This fox, while not being human in appearance, is an example of 'humanity'. He is not human, per se, but it would be wrong to murder him because he is sentient, thinks, and communicates intelligibly.
Let us say that one arrives in the nearest town. The townspeople go out to greet one, but one quickly realizes that the inhabitants cannot speak. They communicate via a series of grunts and hand motions, though they are humans.
Once again, it would be wrong to murder these people. Though they cannot communicate intelligibly with us--or even complex thoughts--they are still human. So it is neither appearance nor the ability to communicate intelligibly that makes one human.
I could proceed to give other examples, but I assume that one sees where I am heading with this. In fact, one probably agrees--it is a combination of characteristics that makes one a 'human' or part of 'humanity'.
One may also say that a fetus possesses none of these.
A fetus is not self-aware.
A fetus does not communicate intelligibly.
A fetus does not think.
A fetus does not have emotions.
A fetus does not have higher mental functions.
Etc.
Therefore, a fetus should not be counted as a human.
But, what about a comatose person--a human who has been unconscious and will remain unconscious for an indefinite period of time.
He is not self-aware.
He does not think. (Though he may have brain activity, he is not thinking.)
He does not communicate intelligibly.
He does not have emotions.
He does not have higher mental functions.
Etc.
Therefore, a comatose person should not be a human or part of humanity.
One may argue that the comatose person will someday recover from the coma and have all characteristics of being human. Will not a fetus one day have all the characteristics of being human? Why would it be wrong to kill the comatose person but acceptable to kill the fetus, then? Both are technically not humans, according to the list of characteristics.
One may also argue that the comatose person already was a human and one cannot lose one's humanity. Fair enough. But, from the list of characteristics, it would certainly seem that the comatose person no longer was human. From an extremely emotionally detached viewpoint, the comatose person is not a human--the same viewpoint from which fetuses are viewed. Clinically, that is.
The idea of humanity is a man-created one. To apply it to one case that does not meet the requisites for being human but not to apply to a different case undermines the nature of it.
As is such, abortion not only is wrong, but it is the murder of the unborn.