The philosopher Peter Singer has cited the following syllogism:
It is wrong to kill an innocent human being.
A human fetus is an innocent human being.
Therefore it is wrong to kill a human fetus.
The conclusions of the pro-life movement in this country are based on the second portion of this argument; that a fetus is an "innocent human being."
Singer and others do not disagree with the second premise, but with the first; that it is wrong to kill an innocent human being. His disagreement with the conclusion, therefore, is based on the idea that it is not always wrong to kill an innocent human being.
Arguments that a fetus, at any stage of development, is not a human life will forever remain a challenge, especially as the ability of salvage a fetus of almost any age, will eventually reach reality. If one accepts the second premise in the above syllogism, then the only way to endorse abortion is to agree to the first premise, as does Singer.
The only way I can place a value on human life is to measure its value when related to another human life, or human lives. It is acceptable, at least philosophically, to sacrifice the life of one innocent person in order to save the lives of many - the old argument of who to toss out of a lifeboat, or whether or not to avoid running over a child, when avoiding the child would result in the destruction of a busload of innocent human beings.
The life of a fetus, at any stage of development, comes into question when its life can impact negatively on the life or health of its mother. Singer bases such decisions on "preferences." What is the preference of the mother compared to the preference of the fetus? A "preference" he defines as something sought to "be obtained or avoided," and to have any preference at all requires the ability to suffer or feel satisfaction. It falls to reason that a very immature fetus could not possibly express a preference, whereas a mother certainly could. This, in Singer's philosophy, would deem the life of the mother more valuable than the life of the fetus, in the difficult situations where a choice must be made between the two.
This argument does not apply to questions of choice in multiple gestations. What should be done if it is deemed necessary to destroy one (or more than one) fetus in order to assure the survival of the others? Which fetus should be sacrificed if all are equally vulnerable? How could this decision be made? Should it be left to the physician to decide?
Talmudic scholars have assessed a mother's life as more valuable than that of her fetus. Violence directed at a pregnant woman that results in the demise of her fetus does not carry a death penalty, but a monetary one. The value of a fetus becomes equal of that of the mother only when one-half of the baby has been delivered.
When a decision as to who obtains a heart transplant has to be made between two individuals, both of whom have equal abilities to suffer or feel satisfaction, it is the one who is most medically needy. If both are equally needy, it is the one who is first on the list.
Difficult decisions or choice will remain difficult decisions of choice - but there are clearly instances where they must be made. Onerous, yes - but necessary, absolutely!