Editing Peter Singer (section)

=== Abortion, euthanasia and infanticide ===
Consistent with his general ethical theory, Singer holds that the right to physical integrity is grounded in a being's ability to suffer, and the right to life is grounded in, among other things, the ability to plan and anticipate one's future. Since the unborn, infants and severely disabled people lack the latter (but not the former) ability, he states that abortion, painless infanticide and euthanasia can be justified in certain special circumstances, for instance in the case of severely disabled infants whose life would cause suffering both to themselves and to their parents. 

In his view the central argument against abortion is ''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''. He challenges the second premise, on the grounds that its reference to human beings is ambiguous as between human beings in the zoological sense and persons as rational and self-conscious. There is no sanctity of human life that confers moral protection on human beings in the zoological sense. Until the capacity for pain develops after "18 weeks of gestation", abortion terminates an existence that has no intrinsic value (as opposed to the value it might have in virtue of being valued by the parents or others). As it develops the features of a person, it has moral protections that are comparable to those that should be extended to nonhuman life as well. He also rejects a backup argument against abortion that appeals to potential: ''It is wrong to kill a potential human being; a human fetus is a potential human being; therefore it is wrong to kill a human fetus.'' The second premise is more plausible, but its first premise is less plausible, and Singer denies that what is potentially an X should have the same value or moral rights as what is already an X. Against those who stress the continuity of our existence from conception to adulthood, he poses the example of an embryo in a dish on a laboratory bench, which he calls Mary. Now if it divides into two identical embryos, there is no way to answer the question whether Mary dies, or continues to exist, or is replaced by Jane and Susan. These are absurd questions, he thinks, and their absurdity casts doubt on the view that the embryo is a human being in the morally significant sense.

Singer classifies euthanasia as voluntary, involuntary, or non-voluntary. (For possible similar historical definitions of euthanasia see Karl Binding, Alfred Hoche and Werner Catel.) Given his consequentialist approach, the difference between active and passive euthanasia is not morally significant, for the required act/omission doctrine is untenable; killing and letting die are on a moral par when their consequences are the same. Voluntary euthanasia, undertaken with the consent of the subject, is supported by the autonomy of persons and their freedom to waive their rights, especially against a legal background such as the guidelines developed by the courts in the Netherlands. Non-voluntary euthanasia at the beginning or end of life's journey, when the capacity to reason about what is at stake is undeveloped or lost, is justified when swift and painless killing is the only alternative to suffering for the subject.