One of the arguments used by pro-abortion individuals is that it is permissible to kill an unborn child because nobody knows when the child gets a soul. Prior to this point, the unborn would not be a human being, and so killing it would not be homicide.
A parallel argument is sometimes made in the case of euthanasia. Some individuals confronted with a loved one who is comatose are counseled that the person’s soul is no longer present, that it has “already gone home to God,” and so it is okay to kill the body that is left over.
Both of these arguments are wrong for a variety of reasons. To see why, let’s begin by looking at when the child gets a soul—i.e., at the point of ensoulment. There are four basic options for the time this can occur: at conception, between conception and birth, at birth, after birth. Let’s look at them in reverse order.
This idea is so far out of Judeo-Christian tradition that it has always been recognized as an impossibility. It is, however, held in a small number of New Age circles. I have read that some New Agers state that some children do not get their souls until several days after birth. This harmonizes with a common New Age idea that souls get to choose the body in which they reincarnate. The idea in this case would be that there is no magic point where a child has to get a soul; it just depends on what soul chooses the body first.
Needless to say, this is a bizarre idea and is not likely to have much traction outside New Age circles. It may become more somewhat more common as abortion and euthanasia lead to a greater push for infanticide and thus a greater desire to rationalize away the humanity of a newly born child.
Scarcely less bizarre than the post-birth hypothesis is the assertion made by some, supposedly based on Genesis 2:7, that one receives a soul and becomes a human when one draws one’s first breath. This fails to appreciate the Bible’s use of metaphor. Breath is a biblical metaphor for one’s spirit or life-principle—since the only living humans in everyday life are breathing humans—but breath and spirit are not the same thing.
The idea that one inhales a soul at birth would suggest that souls are made out of oxygen molecules and that we inhale them and exhale them all the time, two notions incompatible with biblical anthropology. Furthermore, modern science reveals that the unborn have been already “breathing” through the placenta (the pre-birth organ equivalent in function to the mouth), which has been taking oxygen, as well as nutrients, from the mother’s bloodstream.
Today the at-birth view is most often found among pro-abortion Christians. However, from a biblical point of view, it is clear that a child is human before birth. When Mary’s greeting reached Elizabeth’s ears in Luke 1, the unborn John the Baptist leapt for joy in his mother’s womb (1:44); we are also told that he was filled with the Holy Spirit from his mother’s womb (1:15). The unborn John the Baptist is also described as a brephos (Luke 1:41, 44), this being a Greek term meaning “a babe, an infant, a newborn child.” These indicate the humanity of the unborn John the Baptist, who was then in the third trimester (1:36–40).
It is sometimes claimed that Thomas Aquinas believed that the unborn did not acquire a soul until several weeks after conception. This is not true. Aquinas believed that the unborn had a soul (a rational, human soul) from the time it was conceived. However, following Aristotelian science, he (and a few other Western writers) thought that conception was an extended process that did not finish until forty or ninety days into the pregnancy: “The conception of the male finishes on the fortieth day and that of the woman on the ninetieth, as Aristotle says in the IX Book of the Animals” (Aquinas, Commentary on III Sentences 3:5:2).
Aquinas was correct that the unborn receive their souls at conception; he was merely mistaken on when conception was finished, due to the science available. As modern medicine has shown, conception in humans occurs almost instantaneously, as soon as the sperm and the ovum unite. This may occur as soon as twenty minutes after the marital act.
Aquinas and a few other medieval Western writers held the forty-to-ninety-day conception theory, but the biological discoveries of the nineteenth century proved it wrong. The view provides little comfort for abortion advocates today for a variety of reasons. It was based on primitive science. It draws a distinction between males and females that many today would regard as sexist. It was held by only a few writers. No single theologian (even Aquinas) speaks for the Church. The writers who favored the theory also opposed abortion as intrinsically evil at any stage.
When viewed without the lens of Aristotelian science, the biblical view of ensoulment becomes clear. In the Old Testament, the psalmist assumes the humanity of the unborn child at conception when he says, “Indeed, I was born guilty, a sinner when my mother conceived me” (Ps. 51:5, NRSV). This indicates that the unborn child possesses a sinful, fallen nature at the time of conception (though it does not manifest in actual, personal sins until later; cf. Romans 9:11). Since sin is a spiritual phenomenon, the presence of a sinful nature indicates a spiritual nature and thus a soul, making the child a complete human being from conception.
The humanity of the unborn at all stages of development is also indicated by the biblical terminology used to refer to unborn children. The Hebrew term yeled, which means “child, son, boy, offspring, youth,” is used to refer to the unborn child, regardless of the stage of development. (Cf. Ex. 21:22, where the Hebrew says literally “her children come out” instead of “she has a miscarriage,” as in some translations.) The same is true of the term ben, which means “son, child, youth” (cf. Gen. 25:22).
From the biblical perspective, all children are children, whether born or not. The Jews neither had nor needed a specialized term for the unborn, whose humanity they saw clearly. Thus the Hebrew Scripture regularly refers to individuals existing in the womb (“I knew you in the womb,” Jer. 1:5; cf. Job. 10:8–12, Ps. 139:13–16, Is. 44:2).
The Didache, one of the earliest Christian writings outside the New Testament (c. A.D. 70) states, “You shall not procure an abortion, nor destroy a newborn child” (2:1). The Letter of Barnabas (c. A.D. 74) states, “You shall not murder a child by procuring abortion; nor, again, shall you destroy it after it is born” (19). Numerous other references in the early Christian writers condemn abortion as murder.
The possession of the soul at all stages of development is also indicated by natural reason, once one understands what a soul is. From an ultimate perspective, a human is comprised of a human soul serving as the substantial form of a human body (cf. Summa Theologiae I:75:4), as indicated in Genesis 2:7. The fact that a soul is needed to turn a human body into a human has sufficiently penetrated the popular consciousness that people recognize the presence of a soul is tied to the right to life.
This leads to the argument in which pro-abortion individuals try to turn the concept of the soul against pro-lifers by arguing that there is no empirical way of determining the presence the soul, making it a matter of faith or personal opinion.
One response to this argument is to take on the concept of the soul. According to biblical theology, the soul (the spirit) is the life-principle of the body. As such, so long as a human body is alive, it has a human soul, for, James tells us, “the body apart from the spirit is dead” (Jas. 2:26). This point of biblical theology was infallibly proclaimed, using philosophical terminology, by the Council of Vienna (1311–1312). The Council dogmatically defined that the soul is the substantial form of a living human body—the metaphysical form that gives the body its humanness and its life (DS 902 [D 481], CCC 365). When the soul departs, the body ceases to be living, loses its integrity, and begins to decay.
Given this, a pro-life advocate may say that there is an empirical test for the presence of the human soul. Though the soul itself cannot be empirically observed, its presence can be detected (just as an electron itself cannot be directly observed, but the presence of an electron can be detected through various scientific means). The test is simple: If you have a living human body, it is made alive by a human soul. This reduces the issue to the question of biological humanness.
Another way to deal with the argument is to turn the abortion activist’s assertion—that the soul is undetectable—against him. One may argue that if the soul is undetectable, then its presence or absence cannot be used as a test for humanness in a secular society. People cannot be allowed to terminate the lives of others based on their individual beliefs concerning whether their victims have souls. Therefore, we must rely on what we can test, which is whether a life form is biologically human.
This approach will often be more appropriate than arguing about the presence or absence of souls, especially when one is talking with a person of little or no religious faith. It also completely undercuts the argument that the rights of the unborn are a purely religious matter.