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What Is a Human Person and Who Counts as a Human Person?:

A Crucial Question for Bioethics

William E. May

Michael J. McGivney Professor of Moral Theology

John Paul II Institute for Studies on Marriage and Family

at The Catholic University of America

Washington, D.C. 20017


This is a central issue in Catholic theology and contemporary bioethics. I will first summarize the Catholic holistic understanding of the human person, then examine a dualistic understanding of the human person widely accepted in influential bioethical circles, and conclude with a critique of a dualistic anthropology.

1. The Catholic Theological Holistic Understanding of the Human Person

As the Catechism of the Catholic Church affirms, “the human person, made in the image of God, is a being at once corporeal and spiritual” (no. 362). The human body is human and living precisely because it is animated by a spiritual soul (ibid, no. 364). So closely united are body and soul in the human person that one must consider the soul to be the “form” of the “body.” [1] It is only because it is animated by a spiritual soul that the body in question is a living, human body.  As Pope John Paul II has said, the human person’s “rational soul is per se et essentialiter the form of his body,” and the “person, including his body, is completely entrusted to himself, and it is in the unity of body and soul that the person is the subject of his own moral acts.” [2]

Genesis 2 clearly shows that the human body is personal in nature; the human body in fact reveals or discloses the person. For the “man,” on awakening from the deep sleep that the Lord God had cast upon him and on seeing the “woman” who had been formed from his rib, declares: “This one, at last, is bone of my bone and flesh of my flesh” (Gn 2:23). In uttering this cry, the man, as John Paul II has noted, “seems to say: here is a body that expresses the ‘person’.’’ [3] The bodily, sexual nature of the human person is a matter of utmost importance. In fact, sexuality, “by means of which man and woman give themselves to one another through the acts mutual and exclusive to spouses, is by no means something merely biological, but concerns the innermost being of the human person as such.” [4]

The human body reveals a human person; and since the human body is necessarily either male or female, it is the revelation of a man-person or a woman-person. Precisely because of their sexual differences, manifest in their bodies, the man-person and the woman-person can “give” themselves to one another bodily. Moreover, since the body, male or female, is the expression of a human person, a man and a woman, in giving their bodies to one another, give themselves to one another. The bodily gift of a man and a woman to each other is the outward sign of the communion of persons existing between them. And this sign, in turn, is the image of the communion of persons in the Trinity. The human body, thus, is the means and sign of the gift of the man-person to the woman-person and vice versa in the communio personarum we call marriage. John Paul II calls this capacity of the body to express the communion of persons the nuptial meaning of the body. [5]

Moreover, in the bodily, personal act whereby they “give” themselves to each other, the man and the woman open themselves to the “gift” of new human life. The marital or conjugal act, one proper and exclusive to them, is the kind of act per se apt for communicating both a unique kind of love—marital love—and for handing on life from one generation of human persons to the next. [6] The marital act is more than a mere genital act between a man a woman who “happen” to be married; it is indeed one that actualizes their marriage, for in it the husband gives himself to his wife in a receiving sort of way and the wife receives him in a giving sort of way and in this bodily act they are called to cooperate with God in the raising up of new human life. [7]

Finally, the human person, no matter what his condition, is a being of moral worth, the subject of inviolable rights that are to be recognized and respected by others, including the inviolable right of innocent human persons to life, not to be intentionally killed, and the right of children to be born in and through the conjugal act. [8]

Summary of the Understanding of the Human Person in Catholic Theology

We can summarize the understanding of human anthropology in Catholic theology in the following propositions: 1. The human person is a living human body, and, conversely, a living human body is a human person. 2. The male body person is meant to be a gift to the female body person in the communion of persons we call marriage. 3. Human sexuality is itself integral to the human person; it is a good “of the person,” and is meant to be expressed genitally only within marriage in the marital act, one “open” to the goods of communicating life and love.

In this understanding of the human person no distinction is made between a human being and a human person. All human beings are persons. Being a human being, therefore, has crucial moral significance inasmuch as a person surpasses in value the entire material universe and is never to be considered as a mere means or object of use but is rather the kind of entity to whom the only adequate response is love. [9] Being a human being, being a person, makes a tremendous difference.

2. An Influential Understanding of the Human Person Widespread in Contemporary Bioethics

Many contemporary authors prominent in bioethical circles distinguish sharply between being a human being and being a human person. These authors claim that for an entity to be regarded as a person, it must have developed at least incipiently exercisable cognitive capacities or abilities. Perhaps the most prominent advocates of this anthropology, however differently each articulates it in specifying the requisite abilities, are Peter Singer and Michael Tooley; the position is held, however by many contemporary bioethicists, for instance, Daniel Maguire and Ronald Green, and one of its earliest champions was Joseph Fletcher. [10]

According to this anthropology, not all human beings are persons, but only those with the requisite cognitive abilities. Being a human being has of itself no moral significance, and indeed some of the advocates of this position, in particular Singer, assert that those who believe that membership in the human species is of great moral significance are guilty of speciesism, a prejudice similar to such immoral prejudices as racism. [11]

Moreover, on this view our power to generate human life is that aspect of our sexuality that we share with other animals; as such it is part of that world of subpersonal nature over which the conscious person has dominion. As personal and human, our sexuality consists in its ability to enable us to break out of our prison of loneliness and enter into fellowship or communion with another conscious subject. This aspect of our sexuality is personal precisely because its existence depends on consciousness. We can thus sharply distinguish between sexual behavior, which can have various purposes, chief among which is pleasure whether solitary or mutual, and reproductive behavior. And new “reproductive” technologies enable us to overcome the limitations of genital reproductive “roulette” and generate life in the laboratory in order to enhance its quality. [12] As one author expresses the view: “Genital reproduction is less human than laboratory reproduction, more fun, to be sure, but with our separation of baby making from love making both become more human because they are matters of choice, not chance.” [13]

This view of the human person is, of course, dualistic inasmuch as it sharply distinguishes between a living human body and a living human person. Recently Leon R. Kass, chairman of President Bush’s Council on Bioethics, emphasized that the kind of human “dignity” associated with contemporary bioethics and its underlying anthropology is “inhuman,” because it “dualistically sets up the concept of ‘personhood’ in opposition to nature and the body” and thus “fails to do justice to the concrete reality of our embodied lives…and pays no respect at all to the dignity we have through our loves and longings—central aspects of human life understood as a grown togetherness of body and soul.” [14]

If the person really is not his or her body, then the destruction of the life of the body is not as such an attack on a good intrinsic to the human person. Thus the lives of the unborn, the newborn, individuals in a “persistent vegetative state,” and many others are no longer valuable or inviolable. Indeed, the body, on this view, can become a “prison” or an intolerable burden on the person, and one is doing the person a favor and in fact protecting his “right to die” by euthanizing him or assisting him in suicide.

Summary of the Understanding of the Human Person Widely Influential in Bioethics

We can summarize this anthropology in the following propositions: 1. It conceives of the human person dualistically as a conscious subject distinct from and other than his body; 2. It regards the living human body not as the bodily person but as a privileged instrument of the nonbodily person; 3. It regards the procreative or “reproductive” aspect of human sexuality as part of the subhuman world over which the person has dominion and its “relational” or amative aspect as personal insofar as this aspect depends for its existence on consciousness.

3. Critique of Dualistic Anthropology

Dualism separates the consciously experiencing subject—which dualism identifies with the “person”—from that subject’s body. Various arguments show the falsity of dualism. In my opinion one advanced by Patrick Lee is cogent. Lee summarizes it as follows:

1.Sensing is a bodily act, that is, an act performed by a bodily entity making use of a bodily organ. 2. It is the same thing which senses and which understands. 3. Therefore, that which understands is a bodily entity, not a spiritual [or conscious] substance making use of the body. [15]

Peter Singer, for example, engages in acts of sensation much as Fido the dog does. Such acts are and can only be bodily acts, acts that Singer, a bodily being, performs by making use of such bodily organs as eyes, ears, skin, etc. Singer is the same entity who can understand arguments such as his argument regarding speciesism. Singer, who is a person, is thus a bodily entity, not a spiritual or conscious subject using a body other than himself insofar as he is the same entity that engages in acts of sensation and in acts of understanding.

To put matters another way, if someone breaks your arm, he does not damage your instrument but hurts you.

Moreover, why should exercisable cognitive abilities be a trait conferring value on those who have it? Lee raises this issue elsewhere and says that the proper answer is that such functions and the capacity for them are “of ethical significance not because [these functions] are the only intrinsically valuable entities but because entities which have such potentialities are intrinsically valuable. And, if the entity itself is intrinsically valuable, then it must be intrinsically valuable from the moment that it exists,” and the entity with such potentialities exists from the time that a living human body exists. [16]

The dualistic claim that not all human beings are persons but that only those who possess exercisable cognitive abilities are to be so regarded is, moreover, marked by debates among its own advocates over precisely which ability or abilities must be exercisable if an entity is to be classified as a “person.” This claim inevitably leads to arbitrary and unjust criteria of “personhood.” A group of Catholic thinkers in England gives a devastating critique of this arbitrariness; it is worth citing them at length because their critique ably pinpoints the arbitrariness involved. They write:

The rational abilities necessary to these [cognitive] abilities are various, and come in varying degrees in human beings. If actual possession of such abilities is a necessary condition of the claim to be treated justly, questions will have to be faced precisely which abilities must be possessed, and how developed they must be before one enjoys this claim to be treated justly. And these questions can be answered only by choosing which to count as the relevant abilities and precisely how developed they must be to count. But any such line-drawing exercise is necessarily arbitrary….Arbitrary choices may be reasonable and unavoidable in determining some entitlements….But if one’s understanding of human worth and dignity commits one to being arbitrary about who are to be treated justly (i.e., about who are the very subjects of justice), it is clear that one lacks what is recognizable as a framework of justice. For it is incompatible with our fundamental intuitions about justice that we should determine who are the subjects of justice by arbitrary choice. The need for a non-arbitrary understanding of who are the subjects of justice requires us to assume that just treatment is owing to all human beings in virtue of their humanity. This indispensable assumption is also intrinsically reasonable. It is true that the distinctive dignity and value of human life are manifested in those specific exercises of developed rational abilities in which we achieve some share in such human goods as truth, beauty, justice, friendship and integrity. But the necessary rational abilities are acquired in virtue of an underlying or radical capacity, given with our nature as human beings, for developing precisely those abilities. [17]

This dualism, as John Paul has noted, is one of the roots of the “culture of death.” Referring to this dualism in Evangelium vitae, the Holy Father explicitly identified as one of the major roots of the “culture of death” “the mentality which…recognizes as a subject of rights only the person who enjoys full or at least incipient autonomy and who emerges from a state of total dependence on others.” [18]

Indeed, as Germain Grisez has said, “moral thought must remain grounded in a sound anthropology which maintains the bodiliness of the person. Such moral thought sees personal biological, not merely generically biological, meaning and value in human sexuality. The bodies which become one flesh in sexual intercourse are persons; their unity in a certain sense forms a single person, the potential procreator from whom the personal, bodily reality of a new human individual flows in material, bodily, personal continuity.” [19]


1. On this see Council of Vienne (1312; DS, 902); see also Catechism of the Catholic Church, no. 365.

2. Pope John Paul II, Encyclical Veritatis splendor (1993) 48.

3. See Pope John Paul II, “The Nuptial Meaning of the Body,” General Audience of January 9, 1980, in John Paul II, The Theology of the Body: Human Love in the Divine Plan (Boston: Pauline Books and Media, 1997), p. 61.

4. John Paul II, Apostolic Exhortation, The Role of the Christian Family in the Modern World (Familiaris consortio) (1982), 11.

5. See, Pope John Paul II, “The Nuptial Meaning of the Body,” General Audience of January 9, 1980, in John Paul II, The Theology of the Body: Human Love in the Divine Plan, pp. 60-63; “The Human Person Becomes a Gift in the Freedom of Love,” General Audience of January 16, 1980, in ibid, pp. 63-66.

6. Genital coition is indeed the only kind of personal, bodily act through which new human life can be given. Non-married persons can engage in genital coition, but unlike husbands and wives, who have irrevocably “given” themselves to one another in marriage, such persons, so the Catholic understanding of the human person, male and female, contends, have not capacitated themselves to “welcome human life lovingly, nourish it humanely, and educate it religiously,” i.e., in the love and service of God and neighbor. On this see St. Augustine, De genesi ad literam, 9,7 (PL 34, 397). Husbands and wives, however, by getting married, have made themselves “fit” to generate new human life and give it the home it needs and to which it has a right where it can grow and develop. On this see Pope Paul VI, Encyclical, Humanae vitae (1968), 12, Latin text: “coniugii actus…eos idoneos etiam facit ad novam vitam gignendam.”

7. On this see Pope John Paul II, Apostolic Exhortation on The Role of the Christian Family in the Modern World (Familiaris consortio), especially 17-20, 28-32; Karol Wojtyla, Love and Responsibility, trans. H. Willetts (New York: Farrar, Straus, Giroux, 1981), Chapter Four; William E. May, Marriage: The Rock on Which the Family Is Built (San Francisco: Ignatius Press, 1995), Chapter Two; Germain Grisez, Living a Christian Life, Vol. 2 of The Way of the Lord Jesus (Quincy, IL: Franciscan Press, 1993), pp.553-680.

8. On this see Pope John Paul II, Encyclical Evangelium vitae (1995); Congregation for the Doctrine of the Faith,  Donum vitae (1987).

9. See, Wojtyla, Love and Responsibility, p. 41.

10. See Michael Tooley, Abortion and Infanticide (New York: Oxford University Press, 1983); Peter Singer, Rethinking Life and Death: The Collapse of Our Traditional Ethics (New York: St. Martin’s Press, 1994). See also Daniel Maguire, Death by Choice (New York: Doubleday, 1974) and Sacred Choices: The Right to Contraception and Abortion in Ten World Religions (Philadelphia: Fortress Press, 2001), Ronald Green, The Human Embryo Research Debates: Bioethics in the Vortex of Controversy (New York: Oxford University Press, 2001), and Joseph Fletcher, Morals and Medicine (Princeton: Princeton University Press, 1954, 1979) and Moral Responsibility: Situation Ethics at Work (Philadelphia: Westminster Press, 1967).                                   

11. Singer, Rethinking Life and Death, p. 173; cf. pp. 202-206, where Singer elaborates his new “fifth new commandment,” “Do not discriminate on the basis of species.”

12. See Ashley Montagu, Sex, Man, and Society (New York: Putnam’s, 1969), especially Chapter One, “The Pill, the Sexual Revolution, and the Schools.”

13. Joseph Fletcher, “Ethical Aspects of Genetic Controls: Designed Genetic Changes in Man,” New England Journal of Medicine 285 (1971) 776-783; see also Fletcher’s book, The Ethics of Genetic Controls (Garden City,N.Y.: Doubleday Anchor, 1970), significantly subtitled, Ending Reproductive Roulette.

14. Leon R. Kass, M.D., Life, Liberty and the Defense of Dignity: The Challenge for Bioethics (San Francisco: Encounter Books, 2002), p. 17; cf. p. 20.

15. Patrick Lee, “Human Beings Are Animals,” in Natural Law & Moral Inquiry: Ethics, Metaphysics, and Politics in the Work of Germain Grisez, ed. Robert P. George (Washington: Georgetown University Press, 1998), p. 136. Lee develops this argument on pages 136-143.

16. Patrick Lee, Abortion and Unborn Human Life (Washington, D.C.: The Catholic University of America Press, 1997), pp. 26-27; emphasis added.

17.Euthanasia, Clinical Practice and the Law, ed. Luke Gormally (London: The Linacre Centre for Health Care Ethics, 1994), pp. 123-124. A similar critique was advanced in 1978 by Germain Grisez and Joseph Boyle in their book, Life and Death with Liberty and Justice: A Contribution to the Euthanasia Debate (Notre Dame, IN: University of Notre Dame Press, 1979), pp. 220-224.

18. Pope John Paul II, Encyclical Evangelium vitae, 19.

19. Germain Grisez, “Dualism and the New Morality,” in Atti del Congresso sul Settimo Centenario di Santo Tomasso d’Aquino, Vol. 5, L’Agire Morale (Naples: Edizioni Domenicane, 1975), p. 325.

Copyright ©; William E. May 2004

Version: 14th June 2004

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