Don Marquis, “Why Abortion Is Immoral?” in Larry May and others, Applied Ethics: A Multicultural Approach, Prentice Hall, 2011, 5th ed., pp. 443-450.
Marquis argues that most abortions are immoral because they deprive the fetus of a future like ours. This future-like-ours is a future of value; hence, to deny such a future is wrong.
Those opposed to abortion give a version of the premise that the fetus is a human being (looks like a human being, possesses a human genetic code). Those in favor of abortion offer a version of the premise that the fetus is not a person (or a rational agent or a social being). Each in turn relies on a second premise. Those opposed to abortion ordinarily make this second premise broad — for example, to take human life is prima facie wrong. Those in favor of abortion, on the other hand, identify a premise that is narrow in scope so that the fetus will not fall under it: “it is prima facie seriously wrong to kill only persons” or “it is prima facie wrong to kill only rational agents.”
The following counter-examples pose a challenge to each of the premises. The first of these moral premises would include the killing of cancer cells. The second would not explain why killing infants, young children, severely retarded individuals, or the mentally ill is judged wrong. Each side attacks the other for unacceptable moral premises.
Each side retreats in the face of these counter-examples: the anti-abortionists modify their principle to read: “to take the life of a human being is prima facie wrong.” The pro-choicers extend the category “person” to young children and infants, but not to fetuses. Each is faced with arbitrariness: it seems arbitrary to categorize the fetus as a human being (since some development is ordinarily required to qualify as a human being), and it seems arbitrary to describe an infant but not a late-stage fetus as a person.
Marquis does not give up on the search. He examines why people ordinarily regard it as seriously wrong prima facie to take the life of an adult human being. He concludes that it is prima facie seriously wrong to deprive someone of a future/ a future of value/ a future-like-ours. To do so deprives me as the victim “of those activities, projects, experiences, and enjoyments which would otherwise have constituted my future personal life.”
Marquis claims that his position:
1) is incompatible with the view that it is wrong to kill only beings who are biologically human;
2) entails that it may sometimes be wrong to kill nonhuman animals;
3) does not entail that active euthanasia is always wrong;
4) entails that it is straightforwardly wrong to kill children and infants;
5) does not entail that contraception is wrong.
6) does not rest on religious claims or Papal dogma.
7) can’t be accused of speciesism: the soundness of the argument is compatible with euthanasia and contraception.
Marquis attempts to avoid a tyranny of perfectionism by limiting what his position entails and by attempting to identify a fact that most or all persons would agree to—namely, that the fetus is deprived of a future like ours.