The thesis of this paper is that abortion is the killing of a human being, and it is morally wrong. Don Marquis, in his paper Why Abortion is Immoral sets about an eloquent argument that performing an abortion is in the same moral category as killing another human being (Marquis 183, 189-198, 201-202). He begins by explaining why he believes it is wrong to kill: first he says that it is wrong because it brutalizes the one who kills, and also that it deprives others of the individualÆs presence. However, He goes on to argue that these are not the major consequences of killing someone. The major consequences, he believes are that killing a person ôdeprives them of all the experiences, activities, projects, and enjoyments that would otherwise have constituted oneÆs futureö (Marquis 189-198( This, Marquis argues, makes killing wrong because the killing ôinflicts one of the greatest possible losses on the victimö (Marquis 189-198).
What makes this worse, argues Marquis, is not that the victim is deprived of the activities, projects, experiences, and enjoyments of his future life which he enjoys now, but that there are also things which he may not enjoy now, but would have enjoyed in the future, and he is deprived of these, too (Marquis, 189-198). Killing, then, is wrong because it deprives an individual of their future. Carrying this theory forward, it means that it would be wrong to kill any species, not just human species, because it is possible there are species on other planets which also value their future the way we do.
Marquis leaves open the question of whether this theory should be extended to cover animal species, and if so, to what extent (Marquis 189-198). However, he does extend the theory to cover the fact that he does not believe killing is wrong in all cases, such as in active euthanasia. Here he differs with those who believe in sanctity-of-human-life theories, who hold that euthanasia is wrong, ...