This essay is presented with permission from The New Scholasticism,
Vol. LII, 1, Winter, 1978.

Personhood and the Conception Event

by Robert E. Joyce

This essay serves as a brief rationale for the claim that a conceptus or human zygote is essentially a human person. I will argue that the zygote is just as specifically and truly a person as you or I, though less developed. The idea is that conception or fertilization is the point at which a person--at least one individual person, possibly more--definitely begins to exist physically in the space-time world as we naturally and normally perceive this world. This is not offered as a probable conclusion, but as a reasonable certainty. The exact time at which a given conception event or fertilization process terminates may be quite uncertain. But I will maintain that there is definitely a moment of conception, a moment when the fertilization process is fundamentally complete and a single-celled zygote is essentially first in existence.

The basic format of my argument might be stated simply: Every living individual being with the natural potential, as a whole, for knowing, willing, desiring, and relating to others in a self-reflective way is a person. But the human zygote is a living individual (or more than one such individual) with the natural potential, as a whole, to act in these ways. Therefore the human zygote is an actual person with great potential.

In the 1973 Supreme Court decision on abortion, Justice Harry Blackmun's majority opinion contained the claim that the unborn human individual is not a legal person in the whole sense.[1] Since that time the abortion issue has escalated into national and international prominence and does not seem likely to fade away soon. The positions of adherents to both sides of the underlying issues, concerning who is a person and when, are vigorously maintained. Closely associated groups of questions, especially relating to the value of the person as such, will probably assure increasing attention to the meaning of prenatal human life for generations to come.

As early as 1859 the American Medical Association Committee on Criminal Abortions issued a statement protesting the increasing practice of abortion and strongly asserting the importance of legal protection for prenatal human life.[2] As late as 1963, Planned Parenthood was claiming in a brochure that "an abortion kills the life of a baby after it has begun...birth control merely postpones the beginning of life.[3] In the 20th century, until the mid-sixties, the vast weight of medical and legal opinion leaned toward the view that the life that started in the human being as the result of fertilization was worthy of serious moral and legal protection. What has happened in the last ten years? Why have many jurists, scientists and other intellectuals attempted to deny essential personhood to the unborn or at least tried to redefine conception? What new scientific evidence or philosophical insight can justify this shift? I claim that there is none.

In fact, I will try to suggest that we need and can obtain greater philosophical understanding of the good common sense notion that persons can be tiny one-celled creatures just as wonderously as they can be complex trillion-celled creatures. First, I offer a definition of person and some comments by way of clarification. Second, a brief descriptive interpretation of the conception event is presented. Third, responses are given to some significant objections. And in conclusion, I mention a couple of major implications of the idea that the person exists at conception.

I. The Person

The first element of a sound interpretation of what occurs in human conception seems to be a definition of person. Person can be defined as a whole individual being that has the natural potential to know, love, desire, and relate to self and others in a self-reflective way. There are many alternate ways of phrasing the definition, depending upon different needs of emphasis. But it would seem to be crucial that we recognize a person as a natural being, and not simply as a functional being. A person is one that has the natural but necessarily the functional ability to know and love in a trans-sensible or immaterial way. As soon as one would require a person to have the functional ability for this kind of activity, he or she would seem to be slipping into a subjectivistic elitism such that the comatose, senile, and retarded--even the sleeping--would not be regarded necessarily as persons.

This is an unrealistic position that seems to be out of touch with the human condition. If nature has no essential value in our knowing and judging who or what is a person, independent of accepted functional abilities, then there is little hope for recognition of an objective nature transcending the limits of our personal consciousness in anything else.

In recent years some philosophers have adopted what has been called the "developmentalist" interpretation of the beginning of a human person. Daniel Callahan views it this way. "(Abortion) is not the destruction of a human person for at no stage of its development does the conceptus fulfill the definition of a person, which implies a developed capacity for reasoning, willing, desiring, and relating to others--but is the destruction of an important and valuable form of human life."[4] The language of the Supreme Court in Roe v. Wade is harmonious with this perspective.

But I would suggest that a person is not an individual with a developed capacity for reasoning, willing, desiring, and relating to others. A person is an individual with a natural capacity for these activities and relationships, whether this natural capacity is ever developed or not--i.e., whether he or she ever attains the functional capacity or not.  Individuals of a rational, volitional, self-conscious nature may never attain or may lose the functional capacity for fulfilling this nature to any appreciable extent. But this inability to fulfill their nature does not negate or destroy the nature itself, even though it may, for us, render that nature more difficult to appreciate and love. But that difficulty would seem to be a challenge for us as persons more than it is for them.[5]

Neither a human embryo nor a rabbit embryo has the functional capacity to think, will, desire, and self-consciously relate to others. The radical difference, even at the beginning of development, is that the human embryo actually has the natural capacity to act in these ways, whereas the rabbit embryo does not have and never will have it. For all its concern about potentialities, the developmentalist approach fails to see the actuality upon which these potentialities are based. Every potential is itself an actuality. A person's potential to walk across the street is an actuality that the tree beside him does not have. A woman's potential to give birth to a baby is an actuality that a man does not have. The potential of a human conceptus to think and talk is an actuality. This actual polential--not mere logical possibility--would seem to be a much more reasonable ground for affirming personhood than a kind of neo-angelic notion of personhood that requires actual performance of subjectively recognized spiritual activity.[6]

II. Conception: A Descriptive Interpretation

If the person is an individual entity with the natural, though not necessarily functioning, power to think, will, and relate self-reflectively, then when does such an individual actually begin to exist in the world of space and time? There would seem to be but one reasonable point at which to acknowledge the existence of a new individual person in this world. Conception is that moment when the so-called "fertilization" process is complete. From then on, a genetically and physically unique individual is present and growing. In the following description of the conception event, I wish to challenge or correct a few common misunderstandings about conception.

Before a sperm penetrates an ovum, these two cells are clearly individual cells and are parts of the bodies of the man and woman respectively. They are not whole-body cells as is the zygote cell which they crucially help to cause. They are body-part cells. The zygote is a single cell that is a whole body in itself. From within it, comes all the rest of the individual, including the strictly intra-uterine functional organs of the placenta, amnion, and chorion, as well as the rest of the body that is naturally destined for extra-uterine life. The sperm and ovum are not potential life. They are potential causes of individual human life. They do not, even together, become a new human life. In the fertilization process, they become causes of the new human life.

Fertilization is a process. The process may take twenty minutes or several hours. But it has a definite conclusion. The moment at which this process terminates in the resulting zygote can the called the conception event. The sperm and ovum are specific instrumental causes of the new human being. The man and woman are the main agents of this procreative effect. They cause an actual, not a potential, existence of a person in the space-tirne world. They do not cause a person to exist as a person, but they do cause (in an important, if partial, way) a person to exist in this world.

Parental bodily matter (the sperm and ovum) is a crucial element of procreative-causing on behalf of the new being, but is not the stuff out of which this unique bodily being is adequately constituted. The bodily matter of the zygote comes into existence by means of the bodily matter of the parents but does not come from their bodies. It only looks that way to the unphilosophical mind. The matter of the new person proper is constitutively different matter. The chromosomal uniqueness of the zygote is sufficient testimony to the radical difference of both form and matter in this new being. The unique matter of the zygote has traits similar to, but in no way identical with, those of the parents. With the perspective of an evolutionist, who once said that the evolution from non-life to life was a "leap from zero to everything," we might say that the transition from parent body to offspring is a leap from zero self to all of self.

Moreover, the so-called fertilization process is not as passive as the terminology would suggest. The nuclei of the sperm ane ovum dynamically interact. In so doing they both cease to be. One might say they die together. They really should not be said to unite. That suggests that they remain and form a larger whole. But the new single-celled individual is not an in tandem combo of the two parent sex cells. In their interaction and mutual causation of the new being, the sperm and ovum are self-sacrificial. Their nuclei are the subject of the fertilization process; the zygote is the result of this process. There is neither sperm nor ovum once the process of interaction is completed, even though cytoplasmic matter from the ovum remains. It is really a misleading figure of speech to say of the ovum that it is "fertilized" by the sperm, passively as a farmer's field is fertilized. It is proper rather to speak of the sperm-ovum interaction process. There is no such thing as a "fertilized ovum."

Obviously the new individuals growth is ever a process. But neither its coming into existence nor its final exit is a process. We need to be paradoxical in our thinking, not simple-minded and reductionistic, if we are going to appreciate both the process and the non-process factors involved. In contemporary philosophy, when process is valued on a par with substance the dignity of person and nature are served and enhanced. But when process is enthroned above substance, such that, in effect, the process itself is the only substance, we are engaged in a self-deception fraught with epistemological and moral chaos.

At any given moment, a whole living substance--be it a peach tree, a rabbit, or a human person--either is or is not alive. Once it is alive, it is totally there as this particular actual being, even though it is only partially there as a developed actuality. There is no such thing as a potentially living organism. Every living thing is thoroughly actual, with more or less potential: actually itself; potentially more or less expressive of itself. A one-celled person at conception is an actual person with great potential for development and self-expression. That single-celled individual is just as actually a person as you or I, though the actual personhood and personality of the new individual are, as yet, much less functionally expressed.[7]

In fact, the new personality is so little developed that we are not yet able to recognize it functionally, unless we are willing to go beyond the vision of the eyeballs. Many are not willing. As one life scientist remarked, in speaking of the users of the IUD: "...Ignorance is bliss, for the blastocyst is only a little larger than the egg to begin with, and its passage through the womb is unknown and undetectable.[8] The issue thus becomes whether we are prepared to acknowledge the natural roots of the individual's personality within this largely, though not entirely, undifferentiated stage. The genetic differentiation of a zygote or a blastocyst, however, must be reasonably acknowledged as the natural roots of a personality, not of a " dogality " or of a " rabbitality." The human zygote is a member of a unique species of creature. It is not a genus, to which a species is gradually attached. Such a process of attachment can occur in the mind of the observer; but not in the reality of the observed.

No individual living body can "become" a person unless it already is a person. No living being can become anything other than what it already essentially is. From the perspective of the beginning of a living thing, for such a being to become something essentially other---say, for a " subpersonal human animal"[9] to become a person it would have to be a person before it was a person so that it could be said to become.

Moreover, from the point of view of an adult, if, at this moment, I do not simply have a body, but in some radically natural sense I am my body, then, it is likewise perceptive to say or reasonable to conclude that I did not simply get a body at some point, but was that whole body naturally and radically at every point of its time as well as its space. Otherwise, I could never properly say such things as, "When I was conceived...."

III. Objections and Response

"The human conceptus is not necessarily an individual. But individuality is essential to personhood. Therefore, the conceptus cannot be reasonably regarded as a person." Proponents of this argument cite as evidence the fact of so-called "identical" twins and other multiple births resulting from the causality of a single ovum and sperm. They rightly insist that the living zygote which divides in half cannot be viewed as one, identical human being dividing into two. But the evidence would seem to indicate not that there is no individual present at conception, but that there is at least one and possibly more. Jerome Lejeune of Paris, for instance, has indicated that individuality may be fully existent at the point of fertilization, but that so far we do not have the technical capacity to discern how many individuals are present at that point.[10] Moreover, it seems to me that at this very early stage of human development there may occur at times a process of generation similar to that common in other species. In that case, we could say that one of the twins would be the parent of the other. The original zygote could be regarded as the parent of the second, even though we may never know which one was parthenogenically the parent.[11]

There is also the disputed evidence that in the first days of life, twins or triplets sometimes recombine into a single individual.[12] Actually, this could readily mean that one individual's body absorbs the body of the other, resulting in the latter's death at this particular, vulnerable stage in life.

The major type of objection to personhood at conception is some kind of developmentalism, such as gradual ensoulment. Developmentalists claim to take into account life potential as well as life actual, and thereby to give a more reasonable interpretation to the beginning of human personhood. But this approach fails on at least three counts. It tends to confuse process in the collective with process in the individual. It makes a typically utilitarian projection of mechanistic potential onto organic potential. And it seems to suffer from the misleading, yet popular, notion that man is a rational animal.

This gradualist approach does not distinguish sufficiently two kinds of process. There is the process of the cosmos, as it might be called, within which living substances exist, and which causes these individuals to exist in space and time. The individuals themselves are not the subject of the process nor are they the cause of it. This grand process of the whole of physical nature would seem to employ individual substances, such as parents and their gametic cells, in the causation of new individual substances.

But there is another distinctive process, one that occurs within the living individual entities themselves and one which they themselves cause. It is the process of their own unique life and growth. This process is primarily caused by the individuals; not by the environment and the whole process of Nature. The individual in the womb of his or her mother is in charge of the pregnancy, just as every individual in the womb of "Mother Nature" is in charge of its own life and growth, even as it is thoroughly conditioned by its environment.

In their call for attention to potential life, gradualists have really confused two different kinds of potency. The potency to cause something to come into existence is improperly identified with the potency for this new being to become fully what it is. This latter kind of potency applies only to living beings, since only these can grow or become manifestly themselves. The zygote especially exemplifies this later kind of potency--the potency of an existing being to become more expressly what it already is. The ovum and sperm particularly exemplify the first kind of potency--the potency to cause something to come into existence.

One of the important sources of confusion regarding these radically different kinds of potency is the fact that they interweave and interact. The potency to cause something to come into existencewhich is proper to the ovum, for instancealso entails the latent function of disposing the newly caused being (the zygote) to become fully what it is, once it is. And once the zygote is, its potency to become fully itself also entails the latent function of internally causing its own stages of organization and development. But the potency to cause something is radically different from the potency to become something.

The gametic and zygotic cells primarily illustrate this difference and this confluence of potencies. The ovum, for instance, besides having the potency to cause, together with the sperm, something else to come into existence, also has the potency to become fully itself once it is. And, as with all organic potencies, the potency is attained at the beginning of the ovum's existence (even though it is simply a body-part existence). The potency of an ovum to become fully itself, as an ovum, includes its capacity for containing 23 chromosomes, as well as its capacity for causing, together with a sperm cell, a new human being. Moreover, the new human individual, as a zygote, has its own radically different potency for becoming what it is, once it is. And within its potency for becoming what it is, is potency for causing embryonic, fetal, infant, child, adolescent, and adult stages of development, as well as the potency for causing new human beings through the instrumentality of its gametes.

In this age of the electron microscope, we now know that the matter of a zygote is essentially of the same structure as the matter of an adult. Even a hylomorphic (matter-form) theory, then, demands an acknowledgment that the zygote and the adult have the same formal cause.[13] Only the soul of a person could serve the zygote and embryo as an internal final cause of the development of a specifically human brain or of a human anything. No part of a person can be developed through the internal direction of a plant or an animal soul.[14]

A second major flaw in the gradualist approach is its subtle or not so subtle projection of a mechanistic model of development onto an organically developing reality. It fails to distinguish between natural process and artifactual process. Only artifacts, such as clocks and spaceships, come into existence part by part. Living beings come into existence all at once and then gradually unfold to themselves and to the world what they already, but only incipiently, are. Some developmentalists use the analogy of a blueprint in characterizing the zygote. But a blueprint never becomes part of a house, unless it is used to paper the walls.

Moreover, the human zygote is much more than a genetic package. It is a living being that has genes. We do not think that an adult is a package of organs, muscles, and bones, but that he or she is a being who has these structures. The whole of a living being is always, at every stage, much more than the sum of its parts.

A third major weakness in the gradualist approach is the implicit or explicit notion that a human person is a rational animal. But a person is not a rational animal any more than an animal is a sentient plant. Persons are animal-like, plant-like, rock-like, and God-like in many ways. We fall like rocks when dropped. We digest food like animals. And in our contemplative moments we act like God. Essentially, we are a wholly unique kind of material entity; even more different from animals than animals are different from plants.

The latent idea that a human person is an "incarnate spirit" also seems to be at work in many who have a developmentalist approach. One's own body and biology are regarded thoroughly subject to the superior and inevitably imperious judgements of mind and commands of will. The, body is not valued as a vitally identifiable and intrinsic part of our person, but as an alien animal to be civilized by socialization and technology. By implication then one's own body is not regarded as an intrinsic revelation of person but as a sophisticated instrument for personal use and eventual discard. The utilitarian society--well known for its tin cans, paper cups, disposable babies, et al.--can find in the "developmental school" the heart of its rationale.[15]

In this view, nature is not a friend to be known and loved, but an alien, massive, and impersonal monster ultimately to be outwitted and subdued. Thus the most immediately threatening and most symbolic part of this monster is one's body. One should not claim ownership of this body until one is sure he or can handle it: until one is functionally capable of reasoning, desiring, and willing. These are the minimal criteria for a meaningful bodily existence, conferred by the person whose self-concept represents a refusal to be essentially (not exclusively) identified with body and biology. Such is the Cartesian legacy of the gradualist approach.[16]


The point in time when an individual person begins to exist in the spatio-temporal world is one of the most crucial metaphysical and social issues of our age. Induced abortion is a massive enterprise in both the East and West. A recent U. N. estimate cites a conservative figure of fifty million per year. Highly industrialized and presumably progressive nations, such as Japan and the U.S.A., account for more than a million legal abortions in each nation per year. Philosophers on both sides of the Pacific are being challenged anew to make sense of human life beginnings.

In this country, the present movement for a Human Life Amendment, protecting all human life from conception until unneglectful natural death, underscores the need for distinctive philosophical contribution to the issue itself. In my view, prebirth individuals are now being dehumanized-by-definition through quasi-scientific and erroneous philosophical endeavors. The more subtle form of this dehumanization is the attempt to redefine conception in order to justify newer forms of chemical birth control that do not prevent ovulation but rather systematically induce early abortion.[17] This sexual utilitarianism tends to obfuscate the metaphysical features of incipient personhood.

In order to put the issue of personhood and conception into its truest perspective, philosophers are being challenged to represent, clarify, and deepen our understanding of the value of the person in himself or herself. Because this value is, as it were, a seamless robe, our thinking must be woven from the natural, substantive, and non-functional levels of meaning. Otherwise, "quality of life" ethics becomes the "survival of the fittest," of the most functional; and the ethic itself becomes a non-ethic. I think we need an ethics sensitive to a deeper and richer vision of our dignity even as adults, who are dependently developing persons in the environment of space and time. Without appreciable insight into the inexhaustible process of personhood development, we will not be prepared to respect and protect the prenatal person.

Finally, there is hope that in the wisdom of both East and West we will come to realize how we can learn from the prebirth child concerning the meaning of human existence. Eventually, people could come to see, within the studies of fetology and ontology, many points of convergence and mutual resource.[18] And through co-operative endeavors in these and other disciplines, we could learn very much from our prenatal brothers and sisters as we ourselves continue to gestate within the premortal womb of space and time.

St. John's University, Collegeville, Minnesota.


  1. U. S. Supreme Court, Roe v. Wade, January 22, 1973, p. 47.

  2. American Medical Association Committee On Criminal Abortion, 1859.
A resolution was adopted unanimously by the A. M. A., condemning abortion "at every period of gestation, except as necessary for preserving the life of either mother or child," and urging civil protection for fetal life.

  3. Planned Parenthood Federation of America, Plan Your Children For Health and Happiness, 1963.

  4. D. Callahan, Abortion, Law, Choice and Morality (New York, 1970), pp. 497-498.

  5. The recognition of a person involves, in part, a moral decision. This point is made effectively by John Noonan in the booklet How to Argue About Abortion (New York, 1974), p. 10.

  6. Even the potential to receive actuation ("passive potency ") is itself an actuality, that is not had by something lacking it. There are subtle ways to overlook the actuality of potentiality, in the case of personhood. E. g., Louis Dupre does so by using equivocally "person" and "personal" in his essay, "A New Approach to the Abortion Problem," Theological Studies (1973), 481-488.

  7. Cf. Robert and Mary Joyce, Let Us Be Born (Chicago, 1970), pp. 21-24.

  8. N. Berrill, Person In the Womb (New York, 1968), p. 32.

  9. An expression used by H. Tristram Engelhardt, Jr. in "The Ontology of Abortion," Ethics (April, 1974), p. 217 et passim.

  10. J. Lejeune, "The Beginning of a Human Being," a paper presented to
the Academie dos Sciences Morales et Politiques, Paris, Oct. 1, 1973. He is an eminent geneticist.

  11. This kind of explanation is likewise recognized in the position paper
of Scientists For Life, "The Position of Modern Science on the Beginning
of Human Life" (Fredericksburg, Virginia, 1975), p. 18.

  12, This phenomenon is alleged by Andre Hellegers, M.D. in an article, "Fetal Development," Theological Studies (March, 1970), p. 4. Thomas Hilgers, M. D. et al. dispute it. Cf. T. Hilgers, "Human Reproduction: Three Issues for the Moral Theologian," International Review of Natural Family Planning, I, (1977), 115-116.

  13. Thomas Aquinas would be the first to admit it. His minimal conditions are underscored in places such as Q. D. De Anima, 2 ad 2; and 10 ad 1.

  14. For St. Thomas, not only is the soul an internal final cause (as a
formal cause) of the body; but it is also united with the body as an efficient cause. Cf. Q. D. De Anima, 9 and 10. In the light of contemporary genetic evidence, the entrancing and exiting of souls logically required for the mediate-animation interpretation would seem to degrade hylomorphic theory as an integrative theory of natural identity. Perhaps the most notable attempt at mediate animation today is that of J. Donceel.  E. g., see his "Animation and Hominization," Theological Studies, (1970), 76- 105. A thorough Thomistic critique of Donceel's argumentation is given by W. Marshner, "Metaphysical Personhood and the I.U.D.," The Wanderer, (October 10, 1974), p. 7.

  15. An excellent critique of utilitarian ethics is given by G. Grisez, Abortion: The Myths, the Realities, the Arguments (New York, 1970), p. 317 et passim.

  16. Cf. D. Demarco, Abortion in Perspective (Cincinnati, 1974), passim.

  17. E. g., note the attempt of J. Diamond, M.D., "Abortion, Animation, and Biological Hominization," Theological Studies (1975), 305-324.

  18. In fetology, A. M. Liley is perhaps foremost in the world. Cf., e.g., "The Foetus as a Personality," The Australia-New Zealand Journal of Psychiatry, VI (1972), 99-105. Or, e.g., J. Lejeune, "On the Nature of Man," American Journal of Human Genetics (March, 1970), 119-128.