While abortion remains legal in the United States, there are efforts aimed at curtailing and termination abortion rights. While there are some anti-abortion activists who want to strike down abortion rights in one strike, the canny and pragmatic have accepted that they are more likely to achieve their goal using the thousand cuts method. This is a sensible approach: an effort to simply make abortion illegal would meet massive opposition and mobilize the pro-choice forces—it is analogous to an open declaration of war. Various small attempts at limiting abortion rights attract far less attention; they are analogous to minor incidents and attacks that fall far short of full scale war.
One relatively small-scale incursion is focused on narrowing the time scale in which abortion is legal—the idea is to push the time limit ever closer to conception. One stock moral argument used to do this is to contend that at a specific time, the fetus has qualities that grant it a moral status that would make killing it immoral. While some contend that this moment is conception, this position runs into the obvious problem that a single cell seems to lack the qualities that confer meaningful moral status. It also runs into the pragmatic problem that most voters seem to agree with this view and hence it is weak in terms of its persuasive power.
From both a moral and pragmatic standpoint, it is more appealing to make the argument when the fetus has empirically testable qualities that are intuitively relevant to its moral status. These include such qualities as being able to feel pain, able to respond to stimuli and presenting other evidence of the presence of mental activity. While political opponents of abortion rarely advance philosophically rigorous moral arguments, the case is easy enough to make. One obvious approach is the utilitarian one: that the fetus’ capacity to suffer means that it must be included in the moral calculation of abortion. The obvious problem with this approach is that the fetus has far less capacity than the mother and thus her interests would always seem to outweigh the fetus. This is, obviously enough, analogous to similar arguments about the treatment of animals: if the woman’s interests outweigh those of a fetus that is capable of feeling pain, then the same would hold true when the interest of a human conflicts with that of an animal. If the utilitarian approach is adopted to argue in defense of fetuses, then moral consistency would require that the same argument be applied to animals with qualities equal to or greater than a fetus. This would include many animals, such as chickens, cows and pigs. As such, if abortion should be restricted based on the qualities of the fetus, then the killing of animals should be likewise restricted. As such, if abortion should be legally restricted on these moral grounds, then it would seem that vegetarianism should likewise be imposed by law. While utilitarianism does have considerable appeal, there are alternatives.
The stock alternative to utilitarianism is deontology, the view that actions are inherently right or wrong regardless of the consequences. On this sort of view, killing a being that has the right sort of moral status would always be wrong and utilitarian calculations would be irrelevant. On this view, if the fetus has the right sort of status at a specific stage of development, then it would simply be wrong to kill the fetus. As with the utilitarian argument, this would seem to open the moral door for animals as well. For example, if the capacity to feel pain grants the fetus a moral status that forbids killing it and justifies legally restricting abortion, then animals that feel pain must also be granted the same status and legal protection. Put roughly, if abortion should be restricted because fetuses feel pain, then meat consumption should be restricted because animals feel pain. Any arguments advanced involving painless killing of animals to morally justify meat consumption would also justify painless abortion. Obviously enough, moral arguments that contend that it is acceptable to kill animals because they are inferior to us would also apply to developing fetuses.
It must be noted that the above discussion is focused on moral arguments involving the claim that the fetus has moral status because it has certain empirically testable qualities, such as the capacity to feel pain. As such, while arguments based on non-empirical qualities (such arguments based on the soul) can be advanced, they would take the discussion beyond the intended scope of this work. That said, there does seem to be an obvious way to restrict abortion based on empirical qualities while consistently avoiding extending the same legal protection to animals.
Fetuses are, obviously enough, human. Thus, it could be argued that this is the key moral difference between humans and animals that would justify restricting abortion while still allowing killing animals for consumption. One obvious problem with this approach is that if being human is what matters, then the appeal to the other qualities is irrelevant. As such, the argument should simply be that killing humans is wrong, fetuses are human, so killing them is wrong. While this is an option, it does abandon the appeal to qualities argument.
It could, of course, be argued that it is a combination of being human and the other relevant qualities—this would allow for abortion before the fetus has those qualities while also denying animals with those qualities an analogous moral status. The challenge is, of course, showing what it is about being human that makes the moral difference. While humans are humans, it can also be said that cows are cows and the question arises as to what it is about being human that makes the moral difference. If it is a quality, then that quality can be pointed to. If it is mere species membership, then that seems utterly arbitrary and unprincipled—mere speciesism. As such, it would seem that any arguments designed to restrict abortion based on the empirical qualities of fetuses would also apply to animals possessing equal or greater qualities. As such, if the legal restriction of abortion based on the appeal to qualities is justified, the same justification would require legal restrictions on killing animals. Roughly put, restricting abortion in a consistent way would effectively require legally mandating vegetarianism.