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William E. May [1], [2]


           In 1974 Germain Grisez delivered a paper, “Dualism and the New Morality,” at the International Congress celebrating the seventh centenary of the death of St. Thomas Aquinas. In it he showed clearly the dualistic understanding of the human person found in such champions of the “new morality” as Joseph Fletcher, an ardent champion of contraception, abortion, euthanasia, and others. He also clearly uncovered the dualistic understanding of the human person central to the defense of contraception mounted by the so-called “Majority” theologians of the Papal Commission on Population, the Family and Natality. Analyzing the paper misleadingly called the “Majority Report” by those who leaked it to the press (its Latin title was Documentum Syntheticum de paternitate responsabili), Grisez focused on the following passage: “Ipsum donum mutuum per totam vitam perdurat, foecunditas biologica non est continua et est subiecta multis irregularitatibus, ideo in sfaeram humanam assumi et in ea regulari debet” (Documentum Syntheticum, no. 4).

“This sentence,” he said:

…contains several propositions, but the interesting one—which they assert and which I deny—is: foecunditas biologica in sfaeram humanam assumi debet. Obviously, if the biological fecundity of human persons is per se human, it does not need to be assumed into the human sphere. Nothing assumes what it already is or what it has of itself. Thus the majority theologians of the Commission clearly, although implicitly, asserted dualism….In this view sexuality in and of itself is a physiological process belonging to the physical world; the body in and of itself is not the person; the goods of the body are altogether subordinate to “‘personal’ values.” [3]

           By dualism in this essay Grisez understood the anthropology that regards the “person” as the consciously experiencing subject whose body is not a good intrinsic to the person but rather an extrinsic and merely instrumental good. On this view not all living human beings are persons; only those with incipient cognitive abilities can be regarded as persons. [4] Note too that for dualists our power to generate human life is of itself subpersonal or subhuman; human or personal sexuality, as some who held this dualistic view express matters, “is preeminently…the mode whereby an isolated subjectivity [=person] reaches out to communion with another subject…in order to banish loneliness and to experience the fullness of being-with-another in the human project.” [5]

           Precisely because of this anthropology, dualists try to justify killing innocent people. "If the person,” as Grisez noted, “really is not his body, then the destruction of the life of the body is not directly and in itself an attack on a value intrinsic to the human person," [6] and thus abortion, infanticide, and euthanasia can be morally good. Therefore, he concluded:

Christian 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 animal 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. An attack on this biological process is an attack on the personal value of life, not always, indeed, on an existing individual's life, but on human life in its moment of tradition." [7],[8]

           Grisez’s 1974 essay remarkably foreshadows what Pope John Paul II perceptively noted in his 1981 apostolic exhortation on the Role of the Christian Family in the Modern World (Familiaris consortio) when he said: “the difference, both anthropological and moral, between contraception and recourse to the rhythm of the cycle…is a difference which is much wider and deeper than is usually thought, one which involves in the final analysis two irreconcilable concepts of the human person and of human sexuality” (no. 32,6).

           In Familiaris consortio John Paul did not seek to demonstrate this difference—nor was he obliged to do so. As we have seen, Grisez did so in his 1974 paper, and since then others have written extensively on this matter. [9]

            I will now defend the following propositions: (1) the human body is a good intrinsic to a human person, and (2) intentionally killing innocent human persons is always gravely immoral. Then, in (3) conclusion I will comment on the bond between anthropology and morality

I. The Human Body Is a Good Intrinsic to a Human Person

           I will defend this proposition by first (1) noting relevant teaching of Pope John Paul II and then (2) offering philosophical/theological arguments.

1. Relevant Teaching of Pope John Paul II  

           October 7, 1979 was the day that Pope John Paul II, on his first apostolic visit to the United States, celebrated Mass on the Capitol Mall in Washington, D.C., and it is one of the most memorable days in my life. [10] In his homily, called “‘Stand Up’ for Human Life” and perhaps the most eloquent and powerful he ever gave, he declared:

all human life—from the moment of conception and through all subsequent stages—is created in the image and likeness of God. Nothing surpasses the greatness or dignity of a human person. Human life is not just an idea or an abstraction; human life is the concrete reality of a being that lives, that acts, that grows and develops; human life is the concrete reality of a being that is capable of love and of service to humanity. [11],[12]


           John Paul II’s insistence on the truth that the human body is integral to the person was a hallmark of his pontificate; along with his identification of a dualistic anthropology as the root of the “culture of death.” It is in my opinion his greatest contribution to bioethics. He explicitly identified a dualistic understanding of the human person as a major root of the “culture of death.” Thus in his 1995 Encyclical Evangelium vitae he wrote that the culture of death is rooted in the “mentality which tends to equate personal dignity with the capacity for verbal and explicit, or at least perceptible communication” (no. 19).

           But long before 1995 John Paul had emphasized the bodily character of the human person’s existence. As we have seen, he did so in his 1979 “‘Stand Up’ for Human Life” homily; he also did so in his audiences on the “theology of the body” which he initiated on September 5, 1979 and continued through November 28, 1984. In these audiences he often insisted that the human body “reveals” or “expresses” the person and that it is, as it were, the sacrament of the person—an outward sign not only pointing to and signifying a person but inwardly participating in the being of the person. [13]

           John Paul II vehemently rejected a dualistic anthropology in Veritatis splendor 1993). In it he faced head-on the charge, commonly made by revisionist theologians, that the Magisterium's understanding of natural law is "physicalistic" or "biologistic" (n. 47). He declares that this claim "does not correspond to the truth about man and his freedom," and that it "contradicts the Church's teachings on the unity of the human person," who, "in the unity of body and soul...is the subject of his own moral acts" (n. 48). Since the definitive teaching of the Church (cf. Council of Vienne, const. Fidei Catholicae, Fifth Lateran Council, papal bull Apostolici Regiminis, and Vatican Council II, Gaudium et spes, n. 14) maintains that the human person "entails a particular spiritual and bodily structure," it follows that "the primordial moral requirement of loving and respecting the person as an end and never as a mere means also implies, by its very nature, respect for certain fundamental goods" (n. 48), goods such as  bodily life and marital communion (cf. n. 13).

           Note that here John Paul II reminds us that the truth that the human body is integral to the human person who is a unitary being composed of body and soul is defined teaching of the Church and thus has been infallibly proposed by the magisterium.

           He explicitly repudiated as "contrary to the teaching of Scripture and Tradition" (n. 49) the view of those who "reduce the human person to a 'spiritual' and purely formal freedom" and thus misunderstand the moral meaning of the body and human acts involving it. Likening this view to "certain ancient errors...always...opposed by the Church" (e.g., dualistic Manicheism), he then appealed to the teaching of Paul in 1 Cor 6.9-19) on the gravity of such sins as fornication and adultery and to the teaching of the Council of Trent which "lists as 'mortal sins' or 'immoral practices' certain specific kinds of behavior the willful acceptance of which prevents believers from sharing in the inheritance promised to them" (n. 49).

           Another remarkable witness to John Paul II’s vigorous presentation of the preciousness of human bodily life and the truth that the human body is integral to the human person is provided by his December 1989 “Discourse to the Participants of the Working Group [on the Determination of Brain Death and Its Relationship to Human Death].” John Paul II began by emphasizing that the value of human life “springs from what is spiritual in man,” and that the body

receives from the spiritual principle—which inhabits it and makes it what it is--a supreme dignity, a kind of reflection of the Absolute. The body is that of a person, a being which is open to superior values, a being capable of fulfillment in the knowledge and love of God (cf. Gaudium et spes, 12, 15). When we consider that every individual is a living expression of unity and that the human body is not just an instrument or item of property, but shares in the individual’s value as a human being, then it follows that the body cannot under any circumstances be treated as something to be disposed of at will (cf. ibid, 14). [14]

           As this section has shown, throughout his pontificate John Paul II unequivocally affirmed the intrinsic goodness of the human body and human bodily life and that the human body is a good intrinsic to the human person and not, as dualists maintain, a merely instrumental good.

2. Philosophical/Theological Arguments

1. Philosophical Arguments

           Sound philosophical arguments against a dualistic anthropology have been developed since the time of Aristotle. [15] The argument given by St. Thomas Aquinas [16] has recently been developed thoroughly by Patrick Lee. [17] Here I will present, in my own way, this basically Thomistic argument. It is structured as follows:

1.      Eating, reproducing, and sensing, among other kinds of acts, are bodily acts, that is, acts done by a bodily being making use of bodily organs.

2.      The same being that eats, reproduces, and senses also engages in acts of understanding.

3.      Therefore, the being that engages in acts of understanding is a bodily being, not some other being using a body as an instrumental good extrinsic to itself.

           Dualists deny that all living human beings are persons and claim that only those who have some exercisable cognitive abilities are persons. They all affirm that a being that engages in acts of understanding is a person, but they claim that this person’s body is not a good intrinsic to the person but rather an instrumental good extrinsic to the person and other than the person.

           But they cannot deny that the same being that engages in acts of understanding also eats, drinks, senses, and engages in other acts that are bodily in kind and therefore performed by a bodily being making use of bodily organs. But “making use of bodily organs” is not, as they claim, using the body as a good instrumental to the person, i.e., the consciously experiencing subject. Grisez brings this out very well when he shows how masturbation is an act in which the body is instrumentalized in a dualistic way and how this act differs profoundly from the way in which bodily members are “used” in work and play, in communicating, in authentic conjugal intercourse, etc. In masturbating, an individual is choosing to activate his/her sexual capacity precisely in order to have the conscious experience of the process and its culmination. In doing so,

…one chooses to use one’s body as an instrument to bring about that experience in the conscious self. Thus, the body becomes an instrument used and the conscious self its user. In most cases, using one’s body as an instrument is not problematic. This is done when one works and plays, and also when one communicates, using the tongue to speak, the finger to point, the genitals to engage in marital intercourse. In such cases the body functions as part of oneself, serving the whole and sharing in the resulting benefits. By contrast, in choosing to masturbate, one does not choose  to act for a goal which fulfills oneself as a unified, bodily person. The only immediate goal is satisfaction for the conscious self; and so the body, not being part of the whole for whose sake the act is done, serves only as an extrinsic instrument. Thus, in choosing to masturbate one chooses to alienate one’s body from one’s conscious subjectivity. Of course, this self-alienation from the body in no way affects the metaphysical unity of one’s person, since no act of choice can alter a person’s metaphysical constitution. However, the self-alienation is an existential dualism between the body and the conscious self, that is, a division between the two insofar as they are coprinciples of oneself considered as an integrated, acting person. Therefore, to choose to masturbate is to choose a specific kind of self-disintegrity. [18]

           John Finnis made the same point somewhat differently in his reflections on “personal integrity,” the integrity of a being one in soul and body. “Personal integrity,” Finnis said,

…involves…that one be reaching out with one’s will, that is, freely choosing, real goods and that one’s efforts to realize these goods involves, where appropriate, one’s bodily activity, so that that activity is as much the constitutive subject of what one does as one’s act of choice is. That one really be realizing goods in the world; that one is doing so by one’s free and aware choice, that that choice be carried into effect by one’s own bodily action, including, where appropriate, bodily acts of communication and cooperation with other real people—these are the fundamental aspects of personal integrity. [19]

           The conclusion thus follows that dualism is false and that the same being—the human person—engages both in bodily acts of sensing, eating, reproducing, etc. and in acts of understanding. Since the latter are recognized by dualists as acts of a person, so too should be the former. Thus the body is not an instrument of the person, extrinsic to the person, other than the person; rather the body is a good intrinsic to the person, constitutive of his/her being as a person.

2. A Theological Argument

           “‘Let us make man in our image, after our likeness.’…God created man in his image, in the divine image he created him, male and female he created them” (Gen 1.26, 27). This text from Genesis shows us that when God created human persons (for the creature man is a person insofar as he is made in the image of God), he did not create a conscious subject, aware of itself as a self, to whom he then gave a body as an afterthought. Rather human persons were created as bodily, sexual beings, blessed with fertility and told to “be fertile and multiply” (Gen 1.28). In the next chapter of Genesis we read that the “Lord God formed man out of the clay of the ground and blew into his nostrils the breath of life, and so man became a living being” (Gen 2.7). The being he thus created, a human person, was obviously bodily in nature, an entity

constituted by two principles, one low (“dust of the earth”), one high (“breath of life”). The human being first comes to sight as a formed and animated (or breathing) dust of the ground. Higher than the earth, yet still bound to it, the human being has a name, adam (from adamah, meaning “earth” or “ground”) which reminds him of his lowly terrestrial origin. [20]

           Moreover, when the eternal and uncreated Word of God, the Second Person of the Blessed Trinity, became man, to show us how deeply God loves us, he became flesh (logos sarx egeneto; John 1.14). I think we could say that at the incarnation (and note the significance of the term “incarnation,” i.e., “become flesh”) God’s “uncreated Word” became, like us, a “created word,” and this created word was and is a unitary being of body and soul.

           Platonists and other dualists believe that death is the liberation of the soul (the conscious subject) from the tomb of the body. For them the body (Greek soma) is a tomb (Greek sema). This is opposed to Catholic faith. We believe that the soul is immortal and cannot die, but with St. Thomas we hold that the soul is not the person, the I: “anima mea non est ego.” [21] The body (soma) is not a tomb (sema) but, as John Paul II said in his Homily on the Washington Mall, is “the concrete reality of a being that lives, that acts, that grows and develops; human life is the concrete reality of a being that is capable of love and of service to humanity.

II. Intentionally Killing Innocent Human Persons Is Always Gravely Immoral

           I will first (1) show that this proposition has been infallibly taught by the ordinary and universal magisterium of the Church and then (2) offer an argument to defend the truth of this proposition.

1. The Proposition, “Intentionally Killing Innocent Human Persons Is Always Gravely Immoral” Has Been Infallibly Taught by the Ordinary and Universal Magisterium of the Church

           I believe that the following considerations lead us to the conclusion that the proposition in question has been infallibly taught by the ordinary and universal magisterium of the Church: (1) the teaching of the Roman Catechism or Catechism of the Council of Trent; (2) the teaching of the Catechism of the Catholic Church; (3) and in particular the teaching of Pope John Paul II in Evangelium vitae.

1. The Teaching of the Roman Catechism

           In an essay written in 1986, [22] Grisez summarized the teaching of this catechism as follows:

The commandment forbidding killing “was the first prohibition made by God to man” after the deluge; “among the precepts of the Old Law expounded by our Lord, this commandment was mentioned first by him,” and in explaining it, “the Lord points out its twofold obligation”—prohibitory and mandatory. The exposition of the prohibitory part begins by listing kinds of killing not forbidden by the commandment: killing of animals, execution of criminals, killing an enemy in a just war, killing by accident, killing in self-defense. Setting aside these kinds of killing, “all other killing is forbidden, whether we consider the person who kills, the person killed, or the means used to kill.” Moreover, it is important “to form a just conception of the wickedness of murder. The enormity of this sin is manifest from many and weighty passages of Holy Scripture.” [23]

           In a footnote Grisez declares that he does not cite from the Catechism “as if it were by itself decisive, but for its clear and brief formulation.” Continuing, he says, “Perhaps what is most nearly decisive is what is common to all the approved manuals of moral theology in use before Vatican Council II, for their consensus shows what every bishop in the world at that time wished his seminarians to learn and put into practice in the confessional.” [24]

           Later in his essay Grisez shows that “innocent” and “non-innocent” can be considered technical terms in Christian teaching on killing. They “can be defined by the three kinds of cases in which direct [intentional] killing has been considered justifiable…execution of duly convicted criminals, killing of enemy combatants in a just war, and unavoidable killings in self-defense; others killings are of innocents.” [25]

2. The Teaching of the Catechism of the Catholic Church

           The teaching of this catechism, issued in 1992 (definitive and corrected Latin text 1997) is very similar, as one would anticipate, to the teaching of the Catechism of the Council of Trent four centuries earlier. It recapitulates the witness of scripture in nos. 2259-2262, emphasizing that “Scripture specifies the prohibition contained in the fifth commandment: ‘Do not slay the innocent and the righteous’” (no. 2261, citing Ex 23.7) and then declaring: “The deliberate murder of an innocent person is gravely contrary to the dignity of the human being, to the golden rule, and to the holiness of the Creator. The law forbidding it is universally valid: it obliges each and everyone, always and everywhere” (no. 2261). It recognizes that “the legitimate defense of persons and societies is not an exception to the prohibition against the murder of the innocent that intentional killing constitutes” (2263). It thus holds that some kinds of killing can be justified--killing in self-defense, which, like St. Thomas, it considers an unintended effect of an act of preserving life (nos. 2263-64), killing in capital punishment, and killing of enemies in a just war (no. 2266).

3. The Teaching of John Paul II in Evangelium vitae

The following passage is most important:

…the absolute inviolability of innocent human life is a moral truth clearly taught by Sacred Scripture, constantly upheld in the Church’s Tradition and consistently proposed by her Magisterium. This consistent teaching is the evident result of that “supernatural sense of the faith” which, inspired and sustained by the Holy Spirit, safeguards the People of God from error when “it shows universal agreement in matters of faith and morals” [a citation from Lumen gentium,12]. Faced with the progressive weakening in individual consciences and in society of the sense of the absolute and grave moral illicitness of the direct taking of all innocent human life, especially at its beginning and at its end, the Church’s Magisterium has spoken out with increasing frequency in defense of the sacredness and inviolability of human life. The Papal Magisterium, particularly insistent in this regard, has always been seconded by that of the Bishops, with numerous and comprehensive doctrinal and pastoral documents issued either by Episcopal Conferences or by individual Bishops. The Second Vatican Council also addressed the matter forcefully, in a brief but incisive passage [a reference to Gaudium et spes, 27]. Therefore, by the authority which Christ conferred upon Peter and his Successors, and in communion with the Bishops of the Catholic Church, I confirm that the direct and voluntary killing of an innocent human being is always gravely immoral. This doctrine, based upon that unwritten law which man, in the light of reason, finds in his own heart (cf. Rom 2.14-15) is reaffirmed by Sacred Scripture, transmitted by the Tradition of the Church, and taught by the ordinary and universal Magisterium [with a reference to Lumen gentium, 25] (no. 57).

            Properly to interpret this passage, we need to examine the texts from Vatican Council II to which John Paul explicitly referred. There were three such texts: (i) from Lumen gentium, 12;  (ii) from Gaudium et spes, 27; and (iii) from Lumen gentium, 25.

(i) Lumen gentium, 12

           John Paul II cited a small section of this number; here I will put it into its broader context. This reads as follows: “The holy People of God shares also in Christ’s prophetic office….The whole body of the faithful who have an anointing that comes from the holy one (cf. 1 Jn 2.20 and 27) cannot err in matters of belief. This characteristic is shown in the supernatural appreciation of the faith (sensus fidei) of the whole people, when, ‘from the bishops to the last of the faithful’ [a citation from St. Augustine, De Praed. Sanct. 14, 27: PL 44, 980] they manifest a universal consent in matters of faith and morals….”

           By sensus fidei the Council Fathers did not mean the kind of consensus that can be shown by counting noses or taking popular opinion polls. Thus in the chapter of Lumen gentium concerned with the laity, after first speaking of the lay faithful as persons gathered together “in the People of God and established in the one Body of Christ under one head” (no. 33, emphasis added), the Council Fathers then say: “Christ…the great prophet…accordingly both establishes them [the laity] with the appreciation of the faith (sensus fidei) and the grace of the word (cf. Acts 2.17-18; Rev. 19.10)” (no. 35). From this it is evident that the sensus fidei is not manifested when any of the faithful, including the laity, dissent from the teaching of the “one head” (the pope) and the bishops.

(ii) Gaudium et spes, 27

           The relevant text here reads as follows: “the varieties of crimes [against human life] are numerous: all offenses against life itself, such as murder [Latin homocidium], genocide, abortion, euthanasia and willful suicide…” The expression “innocent human life” is not used here, but since this document later speaks of governments’ legitimate right of self defense while at the same time unconditionally condemning “every act of war directed to the indiscriminate destruction of whole cities or vast areas with their inhabitants” (see no. 80), it is clear that no. 27 is condemning the deliberate killing of the innocent.

(iii) Lumen gentium, 25

           Of the three references to Vatican Council II given by John Paul II in Evangelium vitae, no. 57, I think that this passage referred to in footnote number 51 at the end of the paragraph in which John Paul II said: I confirm that the direct and voluntary killing of an innocent human being is always gravely immoral” (italics in the original) is the most important for showing that this proposition has been infallibly proposed by the ordinary magisterium. For in paragraph 25 of Lumen gentium we read:

Although the bishops, taken individually, do not enjoy the privilege of infallibility, they do, however, proclaim infallibly the doctrine of Christ on the following conditions: namely, when, even though dispersed throughout the world but preserving for all that among themselves and with Peter’s successor the bond of communion, in their authoritative teaching concerning matters of faith and morals, they are in agreement that a particular teaching is to be held definitively [Latin text, autentice res fidei et morum docentes in unam sententiam tamquam definitive tenendam convenient]. This is still more clearly the case, when, assembled in an ecumenical council they are, for the universal Church, teachers of and judges in matters of faith and morals, whose definitions must be adhered to with the obedient assent of faith [Latin, quorum definitionibus fidei obsequio est adhaerendum].

           Note that the footnote in Evangelium vitae explicitly referring to this passage in Lumen gentium comes after John Paul II had said, first, that “the Church’s Magisterium has spoken out with increasing frequency in defense of the sacredness and inviolability of human life. The Papal Magisterium, particularly insistent in this regard, has always been seconded by that of the Bishops, with numerous and comprehensive doctrinal and pastoral documents issued either by Episcopal Conferences or by individual Bishops,” and then that “this doctrine, based upon that unwritten law which man, in the light of reason, finds in his own heart (cf. Rom 2.14-15) is reaffirmed by Sacred Scripture, transmitted by the Tradition of the Church, and taught by the ordinary and universal Magisterium” (emphasis added). It seems clear from this that John Paul II himself was affirming, in this passage, that the proposition in question has indeed been infallibly proposed by the ordinary and universal Magisterium of the Church. [26]


           In a pre-Vatican II work Karl Rahner affirmed that the precepts of the Decalogue, as understood by the Church, were infallibly proposed by the “ordinary” magisterium. In an exceptionally important passage he wrote:

The Church teaches these commandments with divine authority exactly as she teaches other “truths of the faith,” either through her “ordinary” magisterium or through an act of her “extraordinary” magisterium in ex cathedra definitions of the Pope or a general council, but also through her ordinary magisterium, that is, in the normal teaching of the faith to the faithful in schools, sermons, and all the other kinds of instruction. In the nature of the case this will be the normal way in which moral norms are taught….It is therefore quite untrue that only those moral norms for which there is a solemn definition…are binding in the faith on the Christian as revealed by God….When the whole Church in her everyday teaching does in fact teach a moral rule everywhere in the world as a commandment of God, she is preserved from error by the assistance of the Holy Ghost, and this rule is therefore really the will of God and is binding on the faithful in conscience. [27]

           This citation shows that it was common teaching by theologians that the core of Catholic moral teaching, which surely includes its teaching on the precepts of the Decalogue, had been infallibly taught by the ordinary magisterium of the Church, and surely nothing taught at Vatican II would call this consensus into question.

           From all this is seems quite clear that the proposition, the intentional killing of innocent human persons is always gravely immoral is infallibly proposed by the magisterium of the Church.

2. An Argument to Show the Truth of the Proposition That Killing Innocent Human Persons Is Always Gravely Immoral

           The basic ethical argument is rooted in the natural law. The first practical principle of natural law is that good is to be done and pursued and evil is to be avoided. [28] With Grisez and others, however, I do not think that this practical principle is a moral norm, if by moral norm we mean a truth that enables us, prior to choice, to distinguish between morally good and morally bad alternatives of choice. The principle good is to be done and pursued and evil is to be avoided does not enable us to do this and is, in fact, used by evil doers to rationalize their behavior.

           In the Christian tradition the first moral principle always has been expressed in religious language in terms of the twofold commandment to love God and neighbor. After all, did not Jesus say, in responding to the question “Teacher, which commandment of the law is the greatest?”: “‘You shall love the Lord your God with your whole heart, with your whole soul, and with all your mind’ [cf. Dt 6.5]. This is the greatest and first commandment. The second is like it, ‘You shall love your neighbor as yourself’ [cf. Lv 19.18]. On these two commandments the whole law is based…” (Matt 22.36-40; cf. Mk 12.28-34; Lk 10.25-28; Rom 13.8ff; Gal 5.14)?

           St. Thomas included the twofold command to love among the first and common principles of natural law, and explicitly said that “all the precepts of the Decalogue [among them, of course, the fifth commandment against killing] are to be referred to these two [love commandments] as conclusions are referred to their common principles,” [29] i.e., their truth is known in light of the truth of the love commandments.

           In his treatment of the Fifth Commandment, St. Thomas made it clear that this precept of the Decalogue unequivocally condemned the deliberate or intentional killing of the innocent; [30] he insisted that even God cannot dispense from this moral requirement. [31]

           St. Thomas also taught that we offend God only by acting contrary to our own good, [32] and it is important to note that in Veritatis splendor John Paul II emphasized the indissoluble bond between love for the fundamental goods of the human person and love for our neighbor. Commenting on the precepts of the second tablet of the Decalogue, i.e., those concerned with actions regarding our neighbor, he reminds us that these precepts are rooted in the commandment that we are to love our neighbor as ourselves, a commandment expressing the “singular dignity of the human person, ‘the only creature that God has wanted for its own sake’” (Veritatis splendor, no. 13, with an internal citation from Gaudium et spes, 22).  After saying this, John Paul II went on to emphasize that we can love our neighbor and respect his dignity as a person only by respecting the real goods meant to flourish in him. Appealing to the words of Jesus to the rich young man, he highlights the truth that “the different commandments of the Decalogue are really only so many reflections on the one commandment about the good of the person, at the level of the many different goods which characterize his identity as a spiritual and bodily being in relationship with God, with his neighbor, and with the material world….The commandments of which Jesus reminds the young man are meant to safeguard the good of the person, the image of God, by protecting his goods.” (ibid). The negative precepts of the Decalogue—“You shall not kill; You shall not commit adultery; You shall not steal; You shall not bear false witness”---all these precepts, the Pope concluded, “express with particular force the urgent need to protect human life, the communion of marriage,” and so on (ibid).

           From all this we can, I think, appreciate why Germain Grisez and his colleagues John Finnis and Joseph Boyle have proposed that the first moral principle, expressed in religious language as the twofold command to love, be formulated for purposes of ethical reflection by referring to the many goods perfective of human persons that are at stake when we make choices. They suggest that the first moral principle should articulate “the integral directiveness of the first principles of practical reasoning when they are working harmoniously in full concert.” [33] By this they mean that it ought to refer to all of the goods that contribute to the integral fulfillment of the human person, i.e., the goods toward which we are naturally inclined, goods such as life itself, marriage and the generation of human life, knowledge of the truth and appreciation of beauty, etc. For with St. Thomas they hold that “reason naturally apprehends as goods and consequently to be pursued in action all those things to which man has a natural inclination…” [34] They then propose that the first principle of morality be articulated, for purposes of ethical reflection as follows: “in voluntarily acting for human goods and avoiding what is opposed to them, one ought to choose and otherwise will those and only those possibilities whose willing is compatible with a will toward integral human fulfillment,” [35] i.e., with one’s will and heart open to all goods meant to flourish in human persons and protected by the precepts of the Decalogue.

           From this premise it follows that one ought never adopt by choice proposals to kill innocent human persons, i.e., intentionally to deprive them of the good of life. This is an ethical argument to defend the truth of our proposition. It expands somewhat on the reasoning St. Thomas used to defend the truth that intentionally killing an innocent person is always gravely immoral. Above it was noted that Aquinas unequivocally condemned such killing as always gravely immoral. But the proposition that the intentional killing of an innocent human person is always gravely immoral is not self-evidently true. Its truth—and the truth of the other precepts of the Decalogue—must therefore be shown or demonstrated, Aquinas insisted, in light of the first and common principles or precepts of natural law, [36] and as we have seen St. Thomas explicitly identified the twofold command of love as the first and common principle or precept of natural law on which the truth of the precepts of the Decalogue depends. [37]

           But Aquinas, who lived in an age of faith, thought that the natural reason of every man could immediately and with “a modicum of consideration” show the truth of these precepts, although he acknowledged that knowledge of these moral truths can become perverted in a few instances because of sin and bad habits, and that that is the reason why they have need of a further “edition,” in addition to their being contained in natural law, through the divine revelation of the Decalogue. [38]  Although he had said that we offend God only by acting contrary to our own good, St. Thomas did not explicitly refer to the goods meant to flourish in us when he wrote of the way we reason from first and common principles to show the truth of the Ten Commandments nor did he seek to identify how we move from knowledge of the first and common principles of natural law (e.g., the twofold commandment of love) to the “proximate conclusions” one can draw from that knowledge.

           Grisez and his associates seek to show how this movement is made, first by their way of reformulating the first principle of morality and second by articulating what they call “modes of responsibility” midway between the first moral principle and specific moral norms. Grisez notes that Aquinas, while not using the expression “modes of responsibility” did articulate some of them, for instance the Golden Rule. I see no need here of taking up the eight different modes of responsibility Grisez et al. articulate. They are all meant to exclude specific ways of acting that are not compatible with a “will toward integral human fulfillment.” [39] I think that the seventh and eighth “modes” they formulate can be expressed as follows: one ought not freely choose to damage, destroy, or impede what is really good, and innocent human life is a good of this kind. Thus intentionally killing innocent human life is always gravely immoral. Such a deliberate act violates a “mode of responsibility” specifying one way of choosing that is not compatible with a will to integral human fulfillment, with a heart open to all the goods intrinsic to the human persons we are to love by respecting those goods.

           Grisez et al. have here sought to develop St. Thomas’s natural law thinking and to identify more clearly the better known precepts of natural law that serve as premises to show the truth of specific moral norms such as the precepts of the Decalogue. Note too that, as we have seen already, John Paul II in Veritatis splendor explicitly related the negative precepts of the Decalogue to the good of the person, that is, to the different goods characterizing his existence, goods such as life itself. It thus seems to me that John Paul II’s way of showing the truth of the proposition, the intentional killing of an innocent human person is always gravely immoral is quite similar to the kind of reasoning employed by Grisez et al.

Conclusion to “Intentionally Killing an Innocent Human Person Is Always Gravely Immoral”

           I think it has now been shown that the truth of this proposition has been infallibly taught by the ordinary exercise of the Church’s magisterium and that this truth can also be demonstrated by ethical reasoning rooted in the natural law. This truth is immeasurably deepened by the new law of love, which in no way denies the natural law but rather fulfills it. Jesus immeasurably deepens the commandment that we are not to kill in his Sermon on the Mount, the magna carta of the Christian life, [40] for there Jesus, after reaffirming the precepts of the Old Law, goes on to condemn anger, the use of abusive language, holding people in contempt, and he admonishes his followers that if they bring their gift to the altar and there remember that their brother has anything against them they should first go and be reconciled with their brother and then come and offer their gift (Matt 5.22-24). Intentionally killing the innocent should be unthinkable for a Christian, one who is called to follow Christ and to be with him a co-redeemer of the world.

3. Conclusion: The Bond Between Anthropology and Morality

           The first part of this paper showed that the human body is a good intrinsic to the person and that a dualistic anthropology which regards the “person” as other than his/her body and the body only as instrumentally good is at the heart of the culture of death that justifies the intentional killing of millions of human beings. The second part gave reasons based on faith and reason to show that the intentional killing of innocent human persons is always gravely immoral. The major reason why such killing is always gravely immoral is that such killing  deprives human persons of the good of bodily life—after all, such killing does not destroy the soul, the “immortal remains” of the person—but it does kill the person who is a bodily being and whose body is integral to his/her being.  Thus there is a tight bond between anthropology and morality, as Grisez so forcefully expressed matters in a passage cited in the introduction to this paper.

           One might legitimately wonder how dualists can deny that the body is integral to the human person. After all, do not all of us have a natural inclination to preserve our bodily life and health, and is not our life as bodily beings a good toward which we are, as St. Thomas maintains, naturally inclined and that reason thus naturally apprehends as a good to be protected?

           This is surely true. In fact, dualists are really not consistent. If a dualist breaks his arm or leg he certainly does not think that he has damaged his instrument but recognizes that he has hurt himself. How then can they think that their bodies are not integral to their being? The answer lies in the choices they have made. An old scholastic adage is this: quidquid recipitur ad modum recipientis recipitur (“whatever is received is received according to the mode of the recipient”). And we make ourselves to be the kind of “receivers” we are in and through the choices that we make.  In Veritatis splendor John Paul II emphasized that human acts “do not produce a change merely in the state of affairs outside of man, but, to the extent that they are deliberate choices [emphasis added], they give moral definition to the very person who performs them, determining his profound spiritual traits [emphasis in original]” (no. 71). Continuing, he called attention to a remarkable passage from St. Gregory of Nyssa’s De Vita Moysis [II,2-3]: “All things subject to change and to becoming never remain constant but continually pass from one state to another, for better or worse….Now human life is always subject to change; it needs to be born ever anew….But here birth does not come about by a foreign intervention, as is the case with bodily beings…; it is the result of free choice. Thus we are in a certain way our own parents, creating ourselves as we will, by our decisions” (cited in Veritatis splendor, no. 71).

           In short, we make ourselves to be the kind of persons who we are in and through our free choices. And, as John Paul II again noted in Veritatis splendor, certain choices, which we can call “commitments,” “’shape’ a person’s entire moral life, and…serve as bounds within which other particular everyday choices can be situated and allowed to develop” (no. 65).

           Many people in our culture have chosen and regularly practice masturbation, contraception, or both. But such acts are rooted in a dualistic understanding of the human person, even if many people who practice them are not aware of this. But those who choose them make themselves to be the kind of persons for whom the intrinsic goodness of bodily life is difficult to see. It is even more difficult for those who have committed themselves to the justification of abortion and the subtle abortion involved in human embryonic stem cell research, etc. As a result, although good arguments have been and are made against masturbation, contraception, abortion, embryonic stem cell research, etc., those arguments fall on deaf ears if those hearing them are still committed to a way of life in which contraception, abortion, etc. are regarded as morally justifiable and indeed necessary. My conclusion then is that what is needed is a metanoia, a change of heart, a new free choice repenting one’s choice to do such things.

           Questions that are meaningful in themselves are not, unfortunately, meaningful for persons who have precluded them by their own free choices and especially by those choices that we can call commitments. I think it is possible to make those questions meaningful and in this way lead some people to question the commitments they have made and to make new choices that are morally good. But perhaps what is most needed is a new evangelization or re-evangelization.


1. I want to thank the following persons who kindly read earlier drafts of this paper, called my attention to errors, some of them serious, and made excellent suggestions for improving it: Germain Grisez, Mark Latkovic, and Kevin Flannery, S.J.

2. William E. May is Michael J. McGivney Professor of Moral Theology at the John Paul II Institute for Studies on Marriage and Family at The Catholic University of America, Washington, D.C.

3. Germain Grisez, “Dualism and the New Morality,” in Atti del Congresso Internazionale (Roma-Napoli, 12-17 aprile 1974): Tommaso d’Aquino nel suo Settimo Centenario, Vol. 5, L’Agire Morale (Napoli: Edizioni Domenicane Italiane, 1975), p. 328.

4. This is clearly the kind of dualism found in the following authors: Joseph Fletcher, Morals and Medicine (Boston: Beacon Press, 1952); Peter Singer, Rethinking Life and Death  (New York: St. Martin’s Press, 1995); Midhael Tooley, Abortion and Infanticide (New York: Oxford University Press, 1986).

5. Anthony Kosnik, et al., Human Sexuality: New Directions in American Catholic Thought (New York: Paulist, 1977), p. 83.

6. Grisez, “Dualism…,” p. 325.

7. Ibid, p. 330.

8. In view of this and similar citations from Grisez, it seems to me that critics like Ralph McInerny, John HIttinger, and Pamela Hall gravely misrepresent his understanding of natural law. Thus Hall, whose work was directed by Alasdair MacIntyre, claims that Grisez’s natural law theory is a “natural law without nature.” See her Narrative and Natural Law: An Interpretation of Thomistic Ethics (Notre Dame, IN: University of Notre Dame Press, 1994), p. 16. See my critique of Hall, McInerny,  Benedict Ashley and others my essay, “New Perspectives on Thomistic Natural Law,” in St. Thomas Aquinas and the Natural Law Tradition: Contemporary Perspectives, eds. John Goyette, Mark Latkovic, and Richard S. Myers (Washington, D.C.: The Catholic University of America Press, 2004), pp. 113-156.

9. I have sought to do this in several places; see, for example, Catholic Bioethics and the Gift of Human Life (Huntington, IN: Our Sunday Visitor, 2000), Chapter Four, “Contraception and Respect for Human Life,” pp. 119-150 see also Paul deLadurantaye, “‘Irreconcilable Concepts of the Human Person’ and the Moral Issue of Contraception: An Examination of the Personalism of Louis Janssens and Pope John Paul II,” Anthropotes: Rivista di Studi su Matrimonio e Famiglia 13.2 (1997) 433-456.

10. I had the great privilege of being present with my family for this Mass and the Holy Father’s great homily.

11. Emphasis added. I use the text of “‘Stand Up’ for Human Life” found in Enchiridion Familiae, eds. Augusto Sarmiento and Javier Escriva Ivars (Madrid: Ediciones Rialp, 1992) 3.2378-2387.Toward the conclusion of the homily John Paul II committed himself to the defense of human life and challenged all those present to “‘Stand Up’ for Human Life.” In an especially eloquent passage he declared: “…we will stand up every time that human life is threatened. When the sacredness of life before birth is attacked, we will stand up and proclaim that no one ever has the authority to destroy unborn life. When a child is described as a burden or is looked upon only as a means to satisfy an emotional need, we will stand up and insist that every child is a unique and unrepeatable gift of God, with the right to a loving and united family….When the sick, the aged, or the dying are abandoned on in loneliness, we will stand up and proclaim that they are worthy of love, care, and respect.”

12. It is worth noting that Leon Kass, the former chairman of President Bush’s Council on Bioethics, observed, in a passage echoing John Paul’s homily, that the kind of human “dignity” associated with the new biology 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.” Leon Kass, Life, Liberty, and the Defense of Dignity: The Challenge for Bioethics (San Francisco: Encounter Books, 2002), p. 17; emphasis added.

13. All these addresses have been gathered together in a one-volume definitive Italian edition, Giovanni Paolo II, Uomo e Donna lo creò (Città Nuova Editrice: Libreria Editrice Vaticana, 1987). The Daughters of St. Paul published cycle one under the title Original Unity of Man and Woman: Catechesis on the Book of Genesis in 1981; cycle two under the title Blessed Are the Pure in Heart: Catechesis on the Sermon on the Mount and the Teaching of St. Paul in 1983; cycles three, four, and five under the title The Theology of Marriage and Celibacy in 1986; and cycle six under the title Reflections on Humanae Vitae in 1985 (Boston: St. Paul Editions). In 1998 the Daughters published the entire series in one volume, Pope John Paul II, Theology of the Body: Human Love in the Divine Plan (Boston: Pauline Books and Media), with an introduction by John Grabowski. Both the Italian text and the four-volume English edition provide paragraph numbers for the different sections of each of the addresses, whereas the one-volume English edition fails to provide them. Their use facilitates finding the location of given texts within the addresses.  See the following General Audiences: October 31, 1979; November 14, 1979; January 9, 1980; May 28, 1980.

14. “Discourse of John Paul II to the Participants of the Working Group,” in Working Group on the Determination of Brain Death and Its Relationship to Human Death (10-14 December 1989) (Pontificiae Academiae Scientiarum Scripta Varia, 83), eds. R. J. White, H. Angstwurm, and I. Carrasco de Paula (Vatican City: Pontifical Academy of Sciences, 1992), no. 2, p. xxiv.

15. See Aristotle, De Anima, Book 1, chapter 2.

16. St. Thomas Aquinas, Summa theologiae, 1, q. 76, a. 1.

17. Patrick Lee, “Human Beings Are Animals,” in Natural Law & Moral Inquiry: Ethics, Metaphysics, and Politics in the Work of Germain Grisez (Washington, D.C.: Georgetown University Press, 1998), pp. 135-151. See also Germain Grisez, Living a Christian Life, Vol. 2 of his The Way of the Lord Jesus (Quincy, IL: Franciscan Press, 1993), pp. 464-467 491-492, 649-651; Germain Grisez and Joseph M. Boyle, Jr., Life and Death with Liberty and Justice: A Contribution to the Euthanasia Debate (Notre Dame, IN: University of Notre Dame Press, 1979), pp. 375-379; John Finnis, Joseph M. Boyle, Jr., and Germain Grisez, Nuclear Deterrence, Morality and Realism (Oxford and New York: Oxford University Press, 1987), pp. 307-309.

18. Grisez, Living a Christian Life, p. 650, emphasis added. Grisez points out, in footnote 190 on p. 650, that the human “good” harmed by masturbatory acts is the body’s capacity for the marital act as an act of self-giving, the capacity Pope John Paul II called the “nuptial meaning of the body.”

19. John Finnis, “Personal Integrity, Sexual Morality, and Responsible Parenthood,” Anthropos (now Anthropotes): Rivista di studi su matrimonio e famiglia 1.1 (1985) 46.

20. Leon Kass, “Man and Woman: An Old Story,” First Things: A Monthly Journal of Religion and Public Life, no. 17. (November 1991) 16.

21. St. Thomas Aquinas, Super primam epistolam ad corinthios, Lectura 1, 10: “anima mea non est ego.”

22. Germain Grisez, “The Definibility of the Proposition: The Intentional Killing of an Innocent Human Being Is Always Grave Matter,” in Persona: Verità e Morale: Atti del Congresso Internazionale di Teologia Morale (Rome, 7-12 aprile 1986) (Roma: Città Nuova Editrice, 1987), pp. 291-313.

23. Ibid, p. 294. Internal citations are Grisez’s translation of the Latin text of Catechismus ex decreto Ss. Concilii Tridentini ad Parochos, Pii V. Pont. Max., iussu editus (Rome: Propangandae Fidei, 1839): 2:125-131 (on the fifth commandment).

24. Ibid, p. 294, footnote 7.

25. Ibid, p. 301.

26. In my opinion the finest treatment of the conditions set forth in Lumen gentium, no. 25, necessary if a teaching is to be considered infallibly proposed by the ordinary and universal magisterium of the bishops united with the pope is given by John Ford, S..J. and Germain Grisez, “Contraception and the Infallibility of the Ordinary Magisterium,” Theological Studies 39.2 (1978) 258-312. See also Grisez, “Infallibility and Specific Moral Norms: A Review Discussion,” The Thomist 49 (1985) 255-271.

27. Karl Rahner, S.J., Nature and Grace: Dilemmas in the Modern Church (London: Sheed & Ward, 1963), pp.  51-52.

28. St. Thomas Aquinas, Summa theologiae, 1-2, q. 94, a. 2: “bonum est faciendum et prosequendum et malum vitandum.” Note that Aquinas formulates this first practical principle of natural reasoning as a proposition. This follows from his teaching that “law” is a “universal proposition of practical reason as ordered to action” (cf. ibid, q. 90, a. 1, ad 2). This is most important because propositions can be true or false. This is not the case with imperatives, which are neither true nor false. What this shows us is that the precepts of natural law are propositions, not imperatives. Hence it is not correct to say that the first precept of natural law is “do good, avoid evil.”

29. [30] Ibid, 1-2, q. 100, a. 3,  ad 1: “illa duo praecepta [Diliges Dominum tuum, et Diliges proximum tuum] sunt prima et communia praecepta legis naturae, quae sunt per se nota rationi humanae…. Et ideo omnia praecepta decalogi ad illa duo referuntur sicut conclusiones ad principia communia.”

30. St. Thomas Aquinas, Summa theologiae, 2-2, q. 64, a. 4: “nullo modo licet occidere innocentem.”

31. Ibid, 1-2, 100, a. 8, ad 3. On this see Patrick Lee, “Permanence of the Ten Commandments: St. Thomas and His Modern Commentators,” Theological Studies 42 (1981) 422-443.

32. St. Thomas Aquinas, Summa contra gentes, Book 3, chapter 122: “Non enim Deus a nobis offenditur nisi ex eo quod contra bonum nostrum agimus.”

33. Germain Grisez, John Finnis, and Joseph Boyle, “Practical Principles, Moral Truth, and Ultimate Ends,” American Journal of Jurisprudence 32 (1987) 128.

34. St. Thomas Aquinas, Summa theologiae, 1-2, q. 94, a. 2: “omnia illa ad quae homo habet naturalem inclinationem, ratio naturaliter apprehendit ut bona, et per consequens ut opere prosequenda…” In a. 2 Thomas lists 3 natural inclinations, but he does not offer a taxative but only an illustrative list, as is shown by the fact that in the next article, q. 94, a. 3, he speaks of a natural inclination to act in accord with reason. Grisez and associates seek to identify all of the goods to which we are naturally inclined; they list 8. On the eight see Grisez, Living a Christian Life, p. 568.

35. Grisez, Christian Moral Principles, p. 184.

36. On this see Summa theologiae, 1-2, q. 100, aa. 1 and 11.

37. St. Thomas also included among the “first and common” principles of natural law the Golden Rule (see Summa theologiae, 1-2, q. 94, 4, ad 1), the principle that “injury is to be done to no one” (“nulli esse malum faciendum”) (ibid, q. 94. a. 2); but in ibid, q. 100, a. 3, ad 1 he explicitly identified the twofold commandments of love as the common principles whose “proximate conclusions” are the precepts of the Decalogue.

38. See ibid.

39. On the “modes of responsibility,” their function and description see Grisez, Christian Moral Principles, p. 225 ff.

40. On this see St. Augustine, The Lord’s Sermon on the Mount, I,1, 5; in Ancient Christian Writers, No. 5 (Westminster, MD: The Newman Press, 1948), pp. 11, 18-21; St. Thomas Aquinas, Summa theologiae, 1-2, q. 69, aa. 1 and 3; John Paul II, Veritatis splendor, nos. 15-16; Grisez, Christian Moral Principles, pp.654-659,

Copyright ©; William E. May 2005

Version: 13th January 2005

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