Natural Law and Abortion

In the current opposition to abortion on moral grounds, the “right to life” principle has attained an indisputable hegemony. But numerous exceptions to this principle are admitted, even by those who stand firmly by the general rule. Self-defense in the face of unjust aggression or threats to life is almost universally approved; just war theory, allowing killing of combatants, has time-honored acceptability; capital punishment is allowed by the Church, albeit with reservations; and many Catholic moral theologians consider threats to the life of a mother to provide an exception to the prohibition of abortion.
The difficulty of the application of the right-to-life principle in discussions of abortion is aggravated by some impossible questions: When is the fetus a human being? When is the soul infused? Many of us, perhaps most of us, would tend toward a “benefit of the doubt” approach — pointing to the moment of conception. If we accept the dogma of the Immaculate Conception, do we need to logically hold that every human conception is ensouled? In any case, no one, short of divine revelation, knows for sure, or even has the possibility of knowing, when the infusion takes place. This is an issue for which there will never be a clear answer.

But is the right-to-life principle the most relevant principle? Are persons considering the morality or immorality of abortion really asking themselves with praiseworthy academic impartiality, “Now, is this fetus really a human being with a prima facie right to life?” Or should other principles take priority? Are there not other natural-law directives that should have the ascendancy in such cases?

The natural law related to the life principle, according to St. Thomas Aquinas in the Summa (Q. 94, 1a2ae), is the first specific precept of natural law, and relates to the tendency of all beings to remain in existence. As applied to humans, it is the “law of self-preservation” for each individual — the instinctive tendency we all have to nurture our existence and maintain it at all costs, unless some supervening rationale demotes this tendency to secondary importance. The corollary duty for us who observe this law operative in some other individual is to respect that tendency, and do nothing to impede it, as long as that individual does not forfeit his rights in some way (e.g., by unjust, lethal aggression).
Aquinas then goes on to enunciate the second specific precept of the natural law, common to humans as well as other animals — namely, to nurture and make provision for their offspring. As applied to humans, who require immensely longer care and education than other animals, the requirements are proportionally more stringent. This law is associated with the instinctive desire of persons to have offspring and their willingness to invest immense energy in children’s upbringing and well-being — even to the point of personal sacrifice, and even to sacrifice of life.
The main “empirical” proof that this is indeed a law of nature is in the emotions and inclinations — the powerful love most parents feel for their offspring, often maintained in spite of setbacks and unrequited love. Parents reflecting on these appetitive phenomena might suspect that they are being subjected to something like a computer program. Nevertheless, like all instincts, the impetus to care for offspring can be interdicted or redirected, depending on circumstances — including, for humans, not only external environmental circumstances, but also prevailing ideas, ideals, and ideologies.
While the law for the individual parent is to mobilize reason and resources to care for their progeny, the corresponding duty for those of us who witness this law operative in the parent is to respect their right to care for children, and do what is in our power to facilitate that objective — or, at least, not place obstacles in the way.
These two natural-law precepts relate differentially to the abortion issue. While the law of “respect for life” includes one’s offspring in a general way, the second law, related to having and caring for offspring, if it be acknowledged to prevail, is much more relevant to the case of abortion — since it is diametrically opposed to a woman’s extermination of her own child in utero. An intentional extermination would seem to belong preeminently to the category of sins deemed “contrary to nature.”
On the other hand, it should be recognized that application of the second precept may change our perspective on some of the common exceptions many are willing to allow regarding the prohibition of abortion. Those who apply the first precept often make an exception for situations threatening the life of the mother, since there is a conflict between two rights to life. But, in light of the second precept, a conflict of rights obtains also in the cases of rape and incest. For, if every woman has a right to conceive and procreate, and if this right implies that she has a right to make that choice voluntarily, no more obvious infractions of that right than rape and incest can be contemplated.
Indeed, the existence of any right implies voluntariness. The right of free speech would be infringed if the speech were made under duress; the right to choose a religion would be meaningless if it were conditioned by threats to life or well-being; the right to eat to preserve one’s life and health would be compromised for someone subjected to forced feeding. Thus, in cases of rape and incest, application of the second precept points out a conflict of rights. The right of the mother — to bear offspring voluntarily — comes into conflict with the presumed right of the human fetus to life. This infringement of the mother’s right certainly has an impact on any obligations the mother would normally have without such infringement. Especially in the case of incest of young children, the stringency of any presumed duties to offspring would seem to be obviously compromised and minimized.
Legislation by civil authorities, unlike morality and natural law, is not concerned per se with moral right and wrong but with preservation of public order, including the protection of legal rights and the emendation of illegal wrongs. And considerations of enforceability inevitably enter into viable lawmaking. The law may tolerate immoral actions that are in the private realm or cannot be effectively prohibited. America’s experience with Prohibition laws in the 1920s offers a classic example: At that time, many strong believers in the evils of alcohol prudently decided that enforcement would be impossible. In recent decades, the abrogation of erstwhile state laws against sodomy, the marital use of contraceptives, and the sale and use of pornography can be characterized as the removal of largely unenforceable legislation. The legalization of prostitution in some areas may fall into the same category.
But arguably, while a blanket legal prohibition of abortion in the present cultural climate may seem unenforceable, the prohibition of abortion may find broad support even among those with “pro-choice” leanings, provided that the three above-mentioned exceptions are allowed. Gallup polls each year from 2004 to 2009 have consistently indicated that slightly over 70 percent of Americans believe either that abortion should be prohibited completely, or allowed only under certain conditions. The extenuating circumstances often cited are cases of rape, incest, and danger to the life of the mother. In European laws, already much less permissive than in the United States, these three exceptions are frequent and basic.
It goes without saying, however, that Christian principles may supersede considerations of conflicts of right related to natural law. Deciding to bring a child into the world after a rape, for example, would be in the same category as gospel admonitions to “go the other mile,” “lend to others without hoping for repayment,” “turn the other cheek,” etc. In situations of problem pregnancies like ectopic gestation, a woman deciding to forfeit her own right to life and her right to nurture and raise her children to bring her child to term would be going even further in “other miles.” From the standpoint of natural law, such decisions would belong in the category of heroic virtue — sacrifices of personal rights that go beyond any normal call to maternal responsibility.


  • Howard Kainz

    Howard Kainz is professor emeritus at Marquette University. He is the author of several books, including Natural Law: an Introduction and Reexamination (2004), The Philosophy of Human Nature (2008), and The Existence of God and the Faith-Instinct (2010).

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