According to Dan Marquis, establishing whether or not a fetus is a person does not advance the abortion debate because the main premises for the arguments of pro-life and pro-choice are problematic.
He asserts that one problem is with the scope of a pro-life argument, which contends that whatever is biologically human has a right to life. The problem, he claims, is that the premise encompasses more than it should (ie. cancer cells). Another problem, according to Marquis, is that the connection between biology and morality is assumed in this case; a connection he finds difficult to make. He also demonstrates a third problem with the argument from biology: "There is no way to show that a fetus is fully human without begging the question."
Marquis also recognizes problems with a common main premise of the pro-choice view which states that, "Only persons have the right to life." In this case he feels that the scope of the premise excludes those that it should not, namely, infants, the severely retarded and some of the mentally ill. Like the premise of the pro-life argument, Marquis also recognizes a problem with the moral relevance of the pro-choice view. This is, that if a person is to be acknowledged on the basis of possessing certain psychological attributes, as he deems consistent with the pro- choice argument, then just as the biological-moral link is questionable, so is the psychological-moral connection problematic. Also, as Marquis points out, there is no way of showing that a fetus is not a "psychological"person without also "begging the question."
Jane English and Dan Marquis are in agreement to the extent that their views both assert that the establishment of the personhood of a fetus does not advance the abortion debate. English argues this by first pointing out that a sharp line cannot be drawn between a person and a non-person, second that even if a fetus is a person, abortion is still justifiable in many cases.
English attempts to demonstrate that a sharp line cannot be drawn so that those on one side of the line are people and those on the other are not. She argues that there are instances where a being may not possess a certain person-like criteria, such as rationality, and yet should be considered a person all the same. Conversely, a being could potentially possess most of that which is thought to constitute a person and yet would not be considered as such. She offers the example of a highly advanced robot in this case. She concludes that there are no core qualities or criteria that can be met in order for a being to be considered a person; there are only typical features.
Even if a fetus could be conclusively shown to be a person, according to English, their would still be instances where abortion is justifiable. To demonstrate this point, she likens abortion to an instance where a woman is acting in self defense against a hypnotized, and thereby innocent attacker. She argues that a person is justified in killing the attacker, although innocent, in instances where no other alternative is available if the person's life or life prospects are threatened.
For Marquis, the moral questions of abortion should rest on the notions of what it is that makes killing seriously wrong. He continues that killing is wrong , in general, when it deprives someone of a "future like ours (FLO)." It is the having of a FLO, not the desire to enjoy a FLO that is crucial for Marquis. Since a fetus has a FLO, abortion is seriously wrong, except in unusual instances such as rape or when the health of the mother is endangered. Curiously, Marquis also includes the first fourteen days after conception as part of these rare instances.
English seems to argue that it is a being's dissimilarity to a person that allows for the permissibility of abortion in some cases. She feels that abortion, during the early months of pregnancy, is permissible when it is in the interests of the mother and the family because the fetus hardly resembles a person at all. During the middle months of pregnancy when the fetus has begun to resemble a person, abortion is only acceptable if the continuation of the pregnancy would cause physical, psychological, economical or