The human embryo is the human being at its very first stage: from the instant of fertilisation until about the eighth week, before becoming a foetus and then the child a mother will bring into the world. The question of its dignity is one of the most decisive in contemporary ethics, because it arises where the human being is smallest, most fragile and most silent — unable to speak, to defend itself or to claim its rights. It is precisely there, the Church teaches, that the moral quality of a civilisation is measured.
For the Catholic faith the embryo is not a thing, nor a promise of a person, nor a clump of cells that would gradually become one: it is a human being at its beginning, bearing from conception the same dignity as every human person. The Catechism puts it without ambiguity: "Since it must be treated from conception as a person, the embryo must be defended in its integrity, cared for and healed, as far as possible, like any other human being"[1]. This conviction does not rest first on a religious dogma, but on a fact established by embryology and interpreted by reason: from fertilisation there exists a new, distinct, living individual that develops on its own behalf.
This article does not cover the general foundation of human dignity — treated in the dignity of the human person — nor the overall method of medical ethics, which belongs to bioethics. It focuses on a single, but decisive, point: who is the embryo, and what do we owe him? It examines in turn what science says about the beginning of life, the philosophical debate on personhood, the witness of Scripture and Tradition, the teaching of the Magisterium, and the contemporary violations of this dignity — from abortion to artificial fertilisation, from preimplantation diagnosis to research on the embryo.
What Is the Dignity of the Embryo?
The embryo, a human being at its beginning
The word embryo comes from the Greek embruon, "the fruit still in the womb". In biological language it denotes the human organism from fertilisation until the end of the eighth week of development; beyond that, we speak of a foetus. But these boundaries are descriptive markers, not changes of nature: embryo, foetus, newborn, child, adult and elderly person are the successive ages of one and the same being, which never ceases to develop in a single continuous movement.
The Catholic thesis can be stated in one sentence: the embryo is not a potential human being, but a human being in development. The nuance is decisive. A human being "in potential" would be something not yet human that would become so by addition from outside. But — apart from accidental somatic mutations and epigenetic regulation, which modulates gene expression without rewriting its text — no new genetic information is added between conception and birth: it is the same individual who, possessing its entire programme from the beginning, unfolds from within what it already is, nourished and sheltered by its mother. One does not become a human being; one is one, and one grows.
A dignity that is neither earned nor measured
The dignity at stake is not a quality acquired with age, consciousness, autonomy or social usefulness. It is ontological: it lies in what the being is, not in what it does or what it appears to be. This is the deep meaning of the doctrine developed in the dignity of the human person: every human being is infinitely precious, by the very fact of being human, regardless of age, health or capacities.
Applied to the embryo, this principle forbids any hierarchy among the ages of life. If dignity depended on size, maturity or performance, then the newborn would be worth less than the adult, the sleeping less than the waking, the sick less than the healthy — which no one dares to maintain consistently. The embryo is in exactly the same situation: it does not yet possess in act all its faculties, but it possesses them in root, as the infant possesses the reason it does not yet exercise.
"Human life is sacred because from its beginning it involves the creative action of God and it remains forever in a special relationship with the Creator, who is its sole end." — Catechism of the Catholic Church, § 2258[2]
Why the embryo is the decisive test of all bioethics
The status of the embryo is not a specialist question: it is the point at which the entire coherence of an ethic of life is at stake. For if we concede that this human being, because it is tiny and voiceless, may be produced, sorted, frozen, experimented upon or eliminated according to our interests, then the very principle of the inviolability of innocent life is abandoned — and it becomes impossible to defend with consistency the sick, the disabled or the dying. "It is not possible to achieve the common good without recognising and protecting the right to life, on which are founded and develop all the other inalienable rights of the human being"[3].
That is why the embryo has become the emblematic locus of the confrontation between two visions of the human person: one that recognises in every human being a received worth, prior to any decision; the other that makes that worth dependent on a threshold, a quality or a consent. "But what is technically possible is not for that reason morally admissible"[4]: the whole debate on the embryo lies in this tension between power and respect.
When Does the Life of a Human Being Begin?
The testimony of embryology: a new individual from fertilisation
The question of the beginning of human life is not, in the first place, philosophical or religious: it is first of all biological, and biology answers it with remarkable clarity. Fertilisation — the encounter of ovum and spermatozoon — is not the mere activation of pre-existing material: it is the constitution of a new organism, endowed with an original genetic heritage, different from that of the father as well as that of the mother, and which will never be reproduced identically.
From the first hours, this zygote pilots its own development: it divides, organises itself, manufactures its own proteins according to an internal programme. It is not an organ of the mother, but a distinct being sheltered by her. This is what the French geneticist Jérôme Lejeune, discoverer of the cause of Down syndrome, summarised in his famous testimony before the United States Senate in 1981:
"To accept the fact that after fertilization has taken place a new human being has come into being is no longer a matter of taste or opinion. The human nature of the human being, from conception to old age, is not a metaphysical contention, it is plain experimental evidence." — Jérôme Lejeune, hearing before the Subcommittee of the United States Senate, 23 April 1981[5]
The Church here does nothing but receive and interpret a scientific fact. As Donum Vitae observes, "as soon as the ovum is fertilized, a life is begun which is neither that of the father nor of the mother; it is rather the life of a new human being with his own growth"[6]. The Magisterium does not claim to settle by decree a point of science; it merely notes that genetic data "provide a valuable indication for discerning by the use of reason a personal presence at the moment of this first appearance of a human life"[7].
Continuity, identity, autonomy: the three marks of the new being
Why affirm that this embryo is already someone, and not merely something on the way to becoming someone? Three features, recognised by embryology, ground this conviction.
First, continuity: from zygote to adult, there is no rupture, no leap, no moment at which one being would replace another. Development is an uninterrupted process; to seek in this continuous line a point where "the human" would suddenly begin is an arbitrary decision, not an observation.
Second, identity: the individual remains the same throughout this development. The embryo is not a draft that nature would correct: it is the same organism which, preserved in its identity, unfolds its potentialities. Proof of this is that decades later, the genetic marks inscribed in the very first cell can still be found in the adult.
Third, autonomy of development: the embryo is not directed from outside; it builds itself. The mother provides shelter and nourishment, but it is the embryo itself that orchestrates its own growth, according to a law it carries within. Now "to develop oneself" is precisely the property of an individual living being, not of a fragment of another organism.
The proposed thresholds and their arbitrariness
Faced with this continuity, proponents of a gradual status for the embryo have proposed various thresholds from which life would deserve protection. Each runs into the same difficulty: it artificially divides a continuous process. The table below summarises the main thresholds invoked and their limits.
| Proposed threshold | When | Argument put forward | Why it does not hold |
|---|---|---|---|
| Implantation | Day 6–7 | "As long as it is not implanted, the embryo is not viable" | Implantation changes place, not the nature of the being: it is already the same individual before and after |
| Day 14 | End of twinning possibility | "Before, individuality is not fixed" | The rare possibility of a twin does not prove the absence of an individual, but of an individual that can give rise to another |
| Brain activity | Around week 6–8 | "No brain, no person" | The criterion would also apply to profound coma; it confuses the person with the current exercise of a function |
| Viability | Around week 22–24 | "Capable of surviving outside the womb" | Viability depends on the medical technology of the moment, therefore on the outside: it measures our means, not the child's worth |
| Birth | Term | "Before, it is not yet a child in its own right" | The newborn is no more autonomous than the foetus at term: only the place has changed |
None of these thresholds is inscribed in the reality of the embryo: all are decisions made from outside, on the basis of an interest or a convention. The only non-arbitrary frontier, because it corresponds to a true beginning, is that of fertilisation.
John Paul II's precautionary principle: mere probability suffices
It is sometimes objected that the exact status of the embryo would remain philosophically uncertain — that one could not prove with absolute certainty that it is already a person. John Paul II grants the hypothesis only to turn it around: even in doubt, one may not dispose of the embryo, just as a hunter has no right to shoot at a shape he suspects of being a human being.
"The issue is so grave that, from the standpoint of moral obligation, the mere probability that a human person is involved would suffice to justify an absolutely clear prohibition of any intervention aimed at killing a human embryo." — Saint John Paul II, Evangelium Vitae, no. 60[8]
The argument is powerful because it does not even presuppose faith: it suffices to admit that there could be a person there for its destruction to become morally unjustifiable. Doubt, far from authorising, obliges prudence.
Is the Embryo a Person? The Philosophical Debate
The argument from continuity and potentiality
The heart of the philosophical debate lies in the definition of the person. For the tradition stemming from Boethius, the person is "an individual substance of a rational nature": not a being that exercises reason at this instant, but a being whose nature is rational. The human embryo, because it is an individual of the human species, possesses this nature from the beginning — even if it does not yet exercise its faculties, any more than the sleeper or the newborn.
This is what is called the argument from active potentiality: the embryo does not merely have the possibility of becoming rational as a block of marble has the possibility of becoming a statue; it bears within itself the internal principle of its development towards the exercise of reason. Stone does not sculpt itself; the embryo, for its part, develops itself towards its fulfilment.
Gradualist theories of "personhood" and their impasse
On the opposite side, certain contemporary philosophers — Peter Singer, Michael Tooley — argue that the quality of "person" is acquired gradually, with self-consciousness, the capacity to desire or to feel. On this logic, neither the embryo nor the newborn would yet be persons, and their elimination would not be murder.
This position has the merit of consistency — but it leads to conclusions that the common moral sense judges monstrous: if personhood is defined by actual consciousness, then infanticide of the infant, the fate of the profoundly demented or the comatose become morally defensible. By refusing the embryo's dignity in the name of consciousness, one no longer stops at the embryo. This is the admission, by these authors themselves, that tying dignity to an exercised capacity destroys the protection of all the weak, and not of the embryo alone. The argument proves too much, and therefore proves nothing.
"How could a human individual not be a human person?"
The Church, for its part, does not claim to demonstrate philosophically the exact moment at which the spiritual soul is created — a point it leaves open (see below). But it refuses to separate the biologically constituted human individual from the human person who deserves respect. Donum Vitae formulates this requirement as a decisive question:
"The presence of a spiritual soul cannot be ascertained by any experimental means. Yet the conclusions of science regarding the human embryo provide a valuable indication for discerning by the use of reason a personal presence at the moment of this first appearance of a human life: how could a human individual not be a human person?" — Congregation for the Doctrine of the Faith, Donum Vitae, I, 1[9]
In other words: since a living individual of the human species is recognised, the burden of proof lies with whoever would deny it the status of person, not with whoever grants it. Even in doubt, the embryo must be held to be a person.
Immediate or delayed animation: what the Church does and does not hold
A distinction many ignore is needed here. The question of at what precise instant God creates and infuses the spiritual soul — at conception (immediate animation) or a little later (delayed animation, a hypothesis once defended by Saint Thomas Aquinas on the basis of an Aristotelian biology now superseded) — has never been definitively settled by the Church as dogma.
But this metaphysical uncertainty changes nothing about the moral requirement. Donum Vitae states it expressly: "The Magisterium has not expressly committed itself to an affirmation of a philosophical nature" about immediate animation, but "it constantly reaffirms that the human being must be respected and treated as a person from the moment of conception"[10]. Respect owed to the embryo therefore does not depend on a thesis about the moment of animation: it is required from fertilisation, because a human being is already there.
What Scripture and Tradition Say
"You knit me together in my mother's womb"
Long before embryology, the Bible regards the unborn child not as a sketch, but as a being already known and loved by God. Psalm 139 contemplates this mystery of beginning:
"For it was you who created my being, knit me together in my mother's womb. [...] My bones were not hidden from you, when I was being made in secret and woven in the depths of the earth. Your eyes saw me yet unformed." — Psalm 139 (138), 13–16[11]
The vocation of the prophet Jeremiah likewise goes back to before his birth, to God's eternal design:
"Before I formed you in the womb I knew you, before you were born I dedicated you, a prophet to the nations I appointed you." — Jeremiah 1:5[12]
The Gospel goes further still: at the Visitation, it is an unborn child — John the Baptist, still in Elizabeth's womb — who recognises the presence of Christ himself still embryonic in Mary's womb. "Now when Elizabeth heard Mary's greeting, the infant leaped in her womb"[13]. Two unborn children are here the first actors in the encounter of the Saviour and his forerunner: Scripture treats the embryo as a subject, already capable of joy and mission.
The Christian rejection of abortion from the very beginning
Respect for the unborn child is not a recent invention: it belongs to the earliest core of Christian morality. The Didache, the manual of the Christian community written at the end of the 1st century or the beginning of the 2nd, ranks abortion among the acts incompatible with the "way of life":
"You shall not kill the child by procuring abortion, nor shall you kill the newborn." — Didache, II, 2[14]
At the turn of the 3rd century, Tertullian already states the continuity argument with striking concision: to prevent birth is to kill, for the human being is already present in what must become him.
"He is already a human being who is going to be one; just as every fruit is already present in the seed." — Tertullian, Apologeticus, IX, 8[15]
This teaching has never varied. The Catechism underscores: "Since the first century the Church has affirmed the moral evil of every procured abortion. This teaching has not changed and remains unchangeable"[16]. The Second Vatican Council solemnly reaffirms it in the modern age:
"Life must be protected with the utmost care from the moment of conception: abortion and infanticide are abominable crimes." — Second Vatican Council, Gaudium et Spes, no. 51[17]
The Magisterium on the Embryo: From Donum Vitae to Dignitas Infinita
Since the last quarter of the 20th century, as medicine acquired unprecedented powers over the beginning of life, the Church has clarified, document after document, the doctrine of respect owed to the embryo. This line is remarkably consistent.
- 18 November 1974Quaestio de abortu
The first major modern clarification: the Declaration on Procured Abortion of the CDF affirms that human life must be respected from fertilisation, "from the first instant of its existence".
- 22 February 1987Donum Vitae
Instruction of the CDF (Card. Ratzinger) "on respect for human life in its origin": establishes the status of the embryo ("how could a human individual not be a human person?") and judges in vitro fertilisation and destructive research on the embryo.
- 25 March 1995Evangelium Vitae
Encyclical of Saint John Paul II: "Gospel of Life" — a culture of life against a culture of death, solemn condemnation of direct abortion and the precautionary principle ("the mere probability…").
- 8 September 2008Dignitas Personae
Instruction of the CDF (Card. Levada): updates Donum Vitae in the face of new techniques — freezing and surplus embryos, preimplantation diagnosis, embryonic stem cells, cloning.
- 8 April 2024Dignitas Infinita
Declaration of the Dicastery for the Doctrine of the Faith: ranks abortion among grave violations of human dignity and reaffirms the protection of "the human being in the initial phase of his existence".
Donum Vitae (1987): respect owed to the embryo
The Instruction Donum Vitae is the founding text of modern doctrine on the embryo. It posits a principle of universal scope:
"From the moment of conception, the life of every human being is to be respected in an absolute way, because man is the only creature on earth that God has willed 'for its own sake' and the spiritual soul of every man is 'immediately created' by God." — Congregation for the Doctrine of the Faith, Donum Vitae, I, 1[18]
From this principle follows an immediate practical consequence: the embryo, from fertilisation, "must be respected and treated as a person", and therefore "from that same moment his rights as a person must be recognized, among which in the first place is the inviolable right of every innocent human being to life"[19].
Evangelium Vitae (1995): the Gospel of Life
With Evangelium Vitae, John Paul II raises the question to the rank of a civilisational issue: he contrasts the "culture of death", which treats weak life as a burden or a commodity, with the "culture of life", which receives every existence as a gift. The encyclical culminates in a declaration of exceptionally solemn character:
"Therefore, by the authority which Christ conferred upon Peter and his Successors, in communion with the Bishops [...], I declare that direct abortion, that is, abortion willed as an end or as a means, always constitutes a grave moral disorder, since it is the deliberate killing of an innocent human being." — Saint John Paul II, Evangelium Vitae, no. 62[20]
The same encyclical explicitly condemns the instrumentalisation of the embryo through research: "the use of human embryos or foetuses as an object of experimentation constitutes a crime against their dignity as human beings"[21].
Dignitas Personae (2008): the person from conception
The Instruction Dignitas Personae applies this doctrine to new techniques. It opens with a formula that sums everything up:
"The dignity of a person must be recognized in every human being from conception to natural death." — Congregation for the Doctrine of the Faith, Dignitas Personae, no. 1[22]
The text then judges preimplantation diagnosis, freezing, cloning and the use of embryonic stem cells — points taken up in detail below.
Dignitas Infinita (2024): the recent confirmation
The Declaration Dignitas Infinita of the Dicastery for the Doctrine of the Faith, published on 8 April 2024 and approved by Pope Francis, ranks abortion among "grave violations of human dignity", alongside war, human trafficking and euthanasia. It recalls, quoting Evangelium Vitae, the nature of the act:
"Procured abortion is the deliberate and direct killing, by whatever means it is carried out, of a human being in the initial phase of his or her existence, extending from conception to birth." — Dicastery for the Doctrine of the Faith, Dignitas Infinita, no. 47[23]
Violations of the Dignity of the Embryo Today
Recognising the embryo as possessing the dignity of a person has concrete consequences that directly challenge several practices now widespread. The Church does not condemn the medicine of fertility or research: it condemns what treats the embryo as an object — produced, sorted, stored, manipulated or destroyed according to the interests of others. The following table gives an overview.
| Practice | What it does to the embryo | Judgment of the Church | Magisterial source |
|---|---|---|---|
| Procured abortion | Eliminates the embryo or foetus | "Grave moral disorder", murder of an innocent | Evangelium Vitae 62; CCC 2271 |
| In vitro fertilisation | Produces the embryo outside the conjugal union; in surplus | Illicit; dissociates procreation from the conjugal act | Donum Vitae II; Dignitas Personae 14–16 |
| Cryopreservation | Suspends and exposes the embryo, reifies it | Offence to its dignity, reduces it to material | Dignitas Personae 18–19 |
| Preimplantation diagnosis | Selects embryos, destroys the others | Eugenic selection, early abortive practice | Dignitas Personae 22 |
| Destructive research | Uses the embryo as material, kills it | "Crime against the dignity of human beings" | Evangelium Vitae 63; Dignitas Personae 31–32 |
| Cloning | Produces the human being as a copy for use | Gravely illicit, instrumentalisation | Dignitas Personae 28–30 |
Abortion: the elimination of the embryo and foetus
Procured abortion is the most direct violation: it deliberately ends the life of the embryo or foetus. The Church's doctrine, as we have seen, has been constant since the 1st century and was solemnly reaffirmed by Evangelium Vitae 62. The Catechism specifies that the canonical penalty of excommunication attached to abortion "is intended to make clear the gravity of the crime committed, the irreparable harm done to the innocent who is put to death, as well as to the parents and the whole of society"[24], without ever narrowing the mercy offered to those who repent.
It must be stressed that this gravity of the act must not be confused with a judgment on persons. The Church knows that many women are led to abortion by distress, loneliness or pressure from others; its firmness on the principle goes hand in hand with boundless compassion for the wounded, and it is also to defend mothers, often abandoned, that it raises its voice.
In vitro fertilisation and surplus embryos
In vitro fertilisation (IVF) raises a twofold problem. On one hand, it dissociates procreation from the union of the spouses, treating the coming of the child as a technical production rather than as the fruit of a mutual gift — the proper subject of bioethical reflection on procreation. On the other hand, and this is what directly concerns the embryo, it habitually produces more embryos than are implanted, creating "surplus embryos" destined for freezing, destruction or research.
Dignitas Personae brings to light the resulting moral impasse: these embryos, true human beings, find themselves "in a situation of injustice which is, in fact, irreparable"[25]. They can neither be destroyed, nor used, nor — without grave difficulties — have their fate decided; their very existence as "surplus" shows that the procedure treated them from the outset as available material.
Cryopreservation of embryos
Cryopreservation prolongs this reification. To freeze an embryo is to suspend a human existence for years, to expose it to a high rate of mortality at the moment of thawing, and to keep it in a state of waiting that depends on the good will of others.
"Cryopreservation is incompatible with respect owed to human embryos: it presupposes their production in vitro, and exposes them to grave risks of death or to alterations of their physical integrity [...]. It deprives them, at least temporarily, of maternal reception and development within gestation and places them in a situation that exposes them to further violations and manipulations." — Congregation for the Doctrine of the Faith, Dignitas Personae, no. 18[26]
Preimplantation diagnosis and eugenic selection
Preimplantation diagnosis (PGD) consists in genetically examining embryos conceived in vitro in order to reimplant only those judged "healthy", and to discard the others. Presented as a medical advance, it is in reality, according to the Church, the purest expression of the eugenic mentality: it makes the embryo's life a matter of quality, and condemns to disposal those who do not meet the criteria.
"Preimplantation diagnosis [...] is in fact directed to a qualitative selection and, consequently, to the destruction of embryos, which constitutes an act of abortion. [...] It is an expression of the eugenic mentality that accepts selective abortion in order to prevent the birth of children affected by various types of anomalies." — Congregation for the Doctrine of the Faith, Dignitas Personae, no. 22[27]
It is here that the dignity of the embryo meets the question of welcoming fragility: to sort embryos according to conformity is to decree that certain human lives are not worth living — exactly the judgment against which the whole doctrine of dignity was constructed.
Research on the embryo and stem cells
The use of human embryos as research material, notably to harvest stem cells, most often presupposes their destruction. The Church judges it gravely illicit, not because it opposes science, but because one may not kill a human being, even to relieve other patients: "it is never licit to carry out an intrinsically illicit action, even with a view to a good end: the end does not justify the means"[28]. It on the contrary strongly encourages research on adult stem cells or those from the umbilical cord, which requires no destruction of embryos and tends to yield more positive clinical results.
Cloning and the production of embryos
Cloning — whether "reproductive", aiming to bring to birth a copied human being, or "therapeutic", aiming to produce embryos in order to extract tissues from them — pushes the logic of instrumentalisation to the extreme: it manufactures the human being as a product intended for use. Dignitas Personae judges so-called therapeutic cloning "wholly incompatible with human dignity": "to create embryos with the intention of destroying them [...] makes the existence of a human being, even at the embryonic stage, into nothing more than a means to be used and destroyed"; "it is gravely immoral to sacrifice a human life for therapeutic ends"[29].
Abortifacient contraceptives
A more discreet, but real, violation comes from certain methods presented as contraceptives which act in part after fertilisation. Evangelium Vitae draws attention to this point: chemical preparations, intrauterine devices and vaccines, "distributed with the same ease as contraceptive means, act in reality as abortifacient means in the very first stages of development of the life of the new individual"[30]. The distinction here is decisive: what prevents conception belongs to another moral debate; what eliminates an embryo already conceived directly touches its dignity.
The Catholic Response: To Welcome, to Care, to Defend
The embryo, a subject of care and not an object of use
The positive reverse of all these prohibitions is luminous: if the embryo is a person, it is also the recipient of care, and not merely protected from destruction. The Catechism affirms: "Since it must be treated from conception as a person, the embryo must be defended in its integrity, cared for and healed, as far as possible, like any other human being"[31]. Foetal medicine, surgery in utero, prenatal diagnosis directed towards care (and not towards selection) are on the contrary eminent expressions of respect for the embryo.
Jérôme Lejeune, defender of the littlest ones
The geneticist Jérôme Lejeune (1926–1994), discoverer of the cause of Down syndrome, embodies this alliance of science and respect. He had hoped that his discovery would make it possible to heal children with trisomy; he saw with pain that it served above all to detect them in order to eliminate them. All his life he defended the dignity of the embryo with the authority of a scientist, refusing to set medicine against life.
"The quality of a civilization can be measured by the respect given to its weakest members." — Saying attributed to Jérôme Lejeune[32]
Declared venerable by the Church in 2021, first president of the Pontifical Academy for Life, Lejeune remains the leading figure of a bioethics that sacrifices neither scientific rigour nor the defence of the "littlest ones".
To welcome, to accompany, to convert our gaze
The Catholic response is not reducible to prohibitions: it is first of all a call to welcome. To welcome the unwanted child, to support mothers in distress, to accompany couples wounded by infertility towards paths that respect the embryo, to propose adoption rather than elimination, to care for the unborn child who is ill instead of eliminating him: all this translates into deeds the conviction that every human beginning is sacred.
This hope rejoins the heart of Christian spirituality: God himself willed to begin his human life as an embryo, in the womb of the Virgin Mary. By assuming even this fragile first instant of existence, the Word sanctified all human beginnings. Respect for the embryo is therefore not only a moral cause: it is a way of recognising, in the smallest of human beings, the trace of the Creator who "knit us together in our mother's womb" — and the face of the One who willed, to save us, to become that tiny child.
To Go Further
- The dignity of the human person — the foundation of the whole doctrine, of which the embryo is the application to the origins of life.
- Bioethics — the personalist method and the panorama of questions at the beginning and end of life.
- The common good, Solidarity, Subsidiarity — neighbouring principles of social doctrine.
- The death penalty — the other frontier of the right to life.
Notes and References
Catechism of the Catholic Church, § 2274 (vatican.va): "Since it must be treated from conception as a person, the embryo must be defended in its integrity, cared for and healed, as far as possible, like any other human being."
1 31Catechism of the Catholic Church, § 2258 (vatican.va), opening of the treatment of the fifth commandment "You shall not kill".
2Saint John Paul II, Evangelium Vitae, 25 March 1995, no. 101 (vatican.va): "It is not possible to achieve the common good without recognising and protecting the right to life, on which are founded and develop all the other inalienable rights of the human being."
3Congregation for the Doctrine of the Faith, Instruction Donum Vitae, 22 February 1987 (Card. Joseph Ratzinger), Introduction, § 4 (vatican.va): "But what is technically possible is not for that reason morally admissible."
4Prof. Jérôme Lejeune, testimony before the Subcommittee of the United States Senate on Separation of Powers (Subcommittee on Separation of Powers), on bill S. 158 ("Human Life Bill"), 23–24 April 1981. Original English: "To accept the fact that after fertilization has taken place a new human being has come into being is no longer a matter of taste or opinion [...] it is plain experimental evidence."
5Congregation for the Doctrine of the Faith, Donum Vitae, I, 1 (vatican.va): "As soon as the ovum is fertilized, a life is begun which is neither that of the father nor the mother; it is rather the life of a new human being with his own growth." The passage takes up the Declaration on Procured Abortion (Quaestio de abortu), CDF, 18 November 1974, nos. 12–13.
6Congregation for the Doctrine of the Faith, Donum Vitae, I, 1 (vatican.va): "The presence of a spiritual soul cannot be ascertained by any experimental means. Yet the conclusions of science regarding the human embryo provide a valuable indication for discerning by the use of reason a personal presence at the moment of this first appearance of a human life: how could a human individual not be a human person?"
7 9Saint John Paul II, Evangelium Vitae, no. 60 (vatican.va): "The issue is so grave that, from the standpoint of moral obligation, the mere probability that a human person is involved would suffice to justify an absolutely clear prohibition of any intervention aimed at killing a human embryo."
8Congregation for the Doctrine of the Faith, Donum Vitae, I, 1 (vatican.va): the Church "has not expressly committed itself to an affirmation of a philosophical nature" as to the moment of infusion of the spiritual soul, but "constantly reaffirms" the moral obligation to respect the human embryo as a person from the moment of conception.
10Psalm 139 (138), 13–16, liturgical translation (adapted from AELF / RSV).
11Jeremiah 1:5, liturgical translation (adapted from AELF / RSV); the Jerusalem Bible has "before I formed you" instead of "before I fashioned you".
12Luke 1:41, liturgical translation (AELF / RSV), narrative of the Visitation: the child (John the Baptist) leaps in Elizabeth's womb at Mary's approach bearing Christ.
13Didache (Teaching of the Twelve Apostles), II, 2, late 1st century or early 2nd; critical edition W. Rordorf and A. Tuilier, The Teaching of the Twelve Apostles, Sources Chrétiennes no. 248bis, Cerf. French translations vary; Greek: "οὐ φονεύσεις τέκνον ἐν φθορᾷ".
14Tertullian, Apologeticus (Apologeticum), IX, 8, ca. 197. Latin text: "Homo est et qui est futurus; etiam fructus omnis iam in semine est." English translation after standard critical editions.
15Catechism of the Catholic Church, § 2271 (vatican.va): "Since the first century the Church has affirmed the moral evil of every procured abortion. This teaching has not changed and remains unchangeable." The paragraph cites the Didache II, 2.
16Second Vatican Council, Pastoral Constitution Gaudium et Spes, 7 December 1965, no. 51 (vatican.va): "Life must be protected with the utmost care from the moment of conception: abortion and infanticide are abominable crimes."
17Congregation for the Doctrine of the Faith, Donum Vitae, I, 1 (vatican.va): "From the moment of conception, the life of every human being is to be respected in an absolute way, because man is the only creature on earth that God has willed for its own sake and the spiritual soul of each man is immediately created by God."
18Congregation for the Doctrine of the Faith, Donum Vitae, I, 1 (vatican.va): the human being "must be respected and treated as a person from the moment of conception, and therefore from that same moment his rights as a person must be recognized, among which in the first place is the inviolable right of every innocent human being to life".
19Saint John Paul II, Evangelium Vitae, no. 62 (vatican.va): "With the authority which Christ conferred upon Peter and his Successors, in communion with the Bishops of the Catholic Church, I declare that direct abortion, that is, abortion willed as an end or as a means, always constitutes a grave moral disorder, since it is the deliberate killing of an innocent human being."
20Saint John Paul II, Evangelium Vitae, no. 63 (vatican.va): "The use of human embryos or foetuses as an object of experimentation constitutes a crime against their dignity as human beings, who are entitled to respect equal to that due to the child already born and to every person."
21Congregation for the Doctrine of the Faith, Instruction Dignitas Personae, 8 September 2008 (Card. William Levada), no. 1 (vatican.va): "The dignity of a person must be recognized in every human being from conception to natural death."
22Dicastery for the Doctrine of the Faith, Declaration Dignitas Infinita, 8 April 2024 (Card. Víctor Manuel Fernández; approved by Pope Francis on 25 March 2024), no. 47 (vatican.va), citing Evangelium Vitae no. 58: "Procured abortion is the deliberate and direct killing, by whatever means it is carried out, of a human being in the initial phase of his existence, extending from conception to birth."
23Catechism of the Catholic Church, § 2272 (vatican.va), on the canonical penalty of excommunication latae sententiae attached to abortion (cf. Code of Canon Law, can. 1398 in the numbering cited by the Catechism; since the reform of Book VI by the apostolic constitution Pascite gregem Dei of 23 May 2021, in force since 8 December 2021: can. 1397 §2).
24Congregation for the Doctrine of the Faith, Dignitas Personae, no. 19 (vatican.va): the thousands of abandoned embryos "reflect a situation of injustice which is, in fact, irreparable"; John Paul II is quoted there: "no morally licit solution is in sight for the human destiny of the thousands upon thousands of 'frozen' embryos".
25Congregation for the Doctrine of the Faith, Dignitas Personae, no. 18 (vatican.va): "Cryopreservation is incompatible with respect owed to human embryos: it presupposes their production in vitro, and exposes them to grave risks of death or to alterations of their physical integrity. [...] It deprives them, at least temporarily, of maternal reception and development within gestation and places them in a situation that exposes them to further violations and manipulations."
26Congregation for the Doctrine of the Faith, Dignitas Personae, no. 22 (vatican.va): preimplantation diagnosis "is in fact directed to a qualitative selection and, consequently, to the destruction of embryos, which constitutes an act of abortion. [...] It is an expression of the eugenic mentality that accepts selective abortion."
27Congregation for the Doctrine of the Faith, Dignitas Personae, no. 21 (vatican.va): "it is never licit to carry out an intrinsically illicit action, even with a view to a good end: the end does not justify the means". On stem cells, nos. 31–32: removal from a living embryo "inevitably causes its destruction and is therefore gravely illicit", whereas methods without destruction (adult tissues, cord blood, foetuses dead by natural death) are licit.
28Congregation for the Doctrine of the Faith, Dignitas Personae, nos. 28–30 (vatican.va): no. 28 defines cloning (asexual reproduction producing "copies"); no. 30: "To create embryos with the intention of destroying them, is completely incompatible with human dignity, even if the intention is to help the sick, because it makes the existence of a human being, even at the embryonic stage, nothing more than a means to be used and destroyed. It is gravely immoral to sacrifice a human life for therapeutic ends."
29Saint John Paul II, Evangelium Vitae, no. 13 (vatican.va): "chemical preparations, intrauterine devices and vaccines" which, "distributed with the same ease as contraceptive means, act in reality as abortifacient means in the very first stages of development of the life of the new individual".
30Prof. Jérôme Lejeune (1926–1994), geneticist, discoverer of the cause of Down syndrome, first president of the Pontifical Academy for Life, declared venerable on 21 January 2021. Saying widely attributed to Professor Lejeune and taken up notably by the Fondation Jérôme Lejeune (in English: "The quality of a civilization is measured by the respect it shows to the weakest of its members"); the exact primary source not having been established, it is given here as a reported saying.
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