Abortion, euthanasia and infanticide
Consistent with his general ethical theory, Singer holds that
the right to life is intrinsically tied to a being's capacity to hold preferences, which in turn is intrinsically tied to a being's capacity to feel pain and pleasure. In his view, the central argument against abortion may be stated as 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.
[15]
In his book
Rethinking Life and Death, as well as in
Practical Ethics, Singer asserts that, if we take the premises at face value, the argument is deductively valid. Singer comments that defenders of abortion attack the second premise, suggesting that the fetus becomes a "human" or "alive" at some point after conception; however, Singer argues that
human development is a gradual process, that it is nearly impossible to mark a particular moment in time as the moment at which human life begins.
Singer's argument for abortion differs from many other proponents of abortion; rather than attacking the second premise of the anti-abortion argument, Singer attacks the first premise, denying that it is necessarily wrong to take innocent human life:[The argument that a fetus is not alive] is a resort to a convenient fiction that turns an evidently living being into one that legally is not alive. Instead of accepting such fictions, we should recognise that despite the fact that a being is human, and alive, this does not in itself tell us whether it is wrong to take that being's life.[16]
Singer states that arguments for or against abortion should be based on utilitarian calculation which weighs the preferences of a woman against the preferences of the fetus. In his view a preference is anything sought to be obtained or avoided; all forms of benefit or harm caused to a being correspond directly with the satisfaction or frustration of one or more of its preferences.
Since a capacity to experience the sensations of suffering or satisfaction is a prerequisite to having any preferences at all, and a fetus, at least up to around eighteen weeks, says Singer, has no capacity to suffer or feel satisfaction, it is not possible for such a fetus to hold any preferences at all. In a utilitarian calculation, there is nothing to weigh against a woman's preferences to have an abortion;
therefore, abortion is morally permissible.
Similar to his argument for abortion, Singer argues that newborns lack the essential characteristics of personhood—"rationality, autonomy, and self-consciousness"
[17]—and therefore
"killing a newborn baby is never equivalent to killing a person, that is, a being who wants to go on living."[18]
http://en.wikipedia.org/wiki/Peter_Singer#Abortion.2C_euthanasia_and_infanticide