Could the proposition
The human soul is created at the moment of conception.
be defined as dogma?
(question idea courtesy Peter Turner, who asked "What paths exist in the Catholic Church for a certain theological position to become recognized as dogma?")
For something to be declared a Dogma, two conditions are required:
1) the statement is within the scope of Dogma. This is, it refers to faith or morals.
2) the statement does not contradict other Dogmas (because the Magisterium cannot contradict itself, as it is infallible on matters of faith and morals).
Regarding 1), it seems clear that the creation of the soul is about faith. Footnote 19 of the Declaration on Procured Abortion (1974), by the Congregation of the Doctrine of the Faith, discussing the views of the timing of the infusion of the soul, states:
It is not within the competence of science to decide between these two views, because the existence of an immortal soul is not a question in its field. It is a philosophical problem from which our moral affirmation remains independent . . . supposing a later animation, there is still nothing less than a human life, preparing for and calling for a soul in which the nature received from parents is completed. One finds here two important points: the question of when the soul is infused is not one that can be decided by any empirical means, and even if the soul were to be infused at some later point in embryological development, the zygote that is present at fertilization is surely a human life. As such it deserves the same respect as is due to any other human being.
Thus, in the most crude terms, the issue of the creation of the soul is not within the real of science, and therefore it belongs to the real of faith.
Regarding 2), the Church has not infallibly pronounced on the issue and there is no other infallible teaching related to this, beyond that (i) the soul has no pre-existence (Origen's related heresy; Enchiridion symbolorum, 403, 456) and that (ii) the soul is immortal (doesn't die with the body).
A comprehensive list of official teachings pertaining the soul can be found in the New Catholic Encyclopedia (second edition, 2003). I quote in extenso:
Solemn Magisterium. Interpreting officially the witness of the Scriptures and tradition concerning the human soul, the teaching authority of the Church solemnly affirms that the Triune God is the creator of the human creature ‘‘constituted, as it were, alike of the spirit and the body’’ (Lateran Council IV in 1215: ibid. 800; cf. Vatican Council I: ibid. 3002); ‘‘that man has one rational and intellectual soul’’ (Council of Constantinople IV in 870: ibid. 657; there the doctrine of the two souls in man was condemned as heretical); ‘‘that the rational or intellective soul is the form of the human body in itself and essentially’’ (Council of Vienne in 1312 against Peter John Olivi: ibid. 902, cf. 900, 1440); and that the human soul is ‘‘immortal and multiple according to the multitude of bodies into which it is infused, multiplied, and to be multiplied . . .’’ (Lateran Council V in 1513 against some humanistic Aristotelians who renewed the Averroistic monopsychism: ibid. 1440).
Ordinary Magisterium. Man is so substantially one, according to the ordinary teaching authority of the Church, that his unity (which is not accidental) has ontological priority before the real and irreducible plurality of his being. He is one in origin, being, and final destiny (Enchiridion symbolorum 502, 2828, 3005, 3221–22, 3224). Therefore each consideration of a part or one aspect of man implies repercussions concerning all parts and aspects. Any division of man is always inadequate, because as a microcosm (ibid. 3771) he must be considered as a whole. However, since there is an essential difference between matter and SPIRIT (ibid. 3891; cf. 3022–24), there is a real plurality of realities in man which are irreducible to each other. Thus the spiritual soul is not an emanation or a part of man’s matter or body (ibid. 3022, 3220–21, 3896), and it is equally true that the matter cannot be deduced from or reduced to the finite human spiritual soul. Both need a special creative act of God in order to exist, because they are ontologically different (ibid. 360, 3896). Thus man possesses the vital (ibid. 2833) and constitutive principle of his being, i.e., one spiritual, simple, and substantial soul (ibid. 791, 801, 900, 1440), which despite the substantial unity of being in man, is in its being and meaning essentially different and independent of matter (ibid. 1007, 3002, 3022, 3220–24, 3896), and immortal (ibid. 1440). Since the soul is spiritual in itself, man is not composed of three different realities, i.e., body, soul, and spirit, but is a substantial unity in body and spiritual soul only (as opposed to all sorts of trichotomy: ibid. 301, 502, 657, 900, 902, 1440–41, 2828). The approval by the ordinary magisterium of the Thomistic theses concerning the human soul (ibid. 3613–22) must be understood as a favorable reception of them as one of the best illustrations of the mystery of man.
In conclusion, the proposition could be declared as dogma.
The simple answer is, there is a simple and direct path. The Pope as the Supreme Interpreter & Guarantor of Faith can proclaim it a Dogma ex.Cathedra any given day and it will be binding to the Universal Church.
Pope Francis INFALLIBILITY is a Dogma decreed in Vatican I in 1870.
The voice of Peter is the Voice of Christ. "He who hears you hears me" (Luke 10:16),
Peter was given the Keys to God's Kingdom and whatever he bind on earth is bound in Heaven. and "Whatever you bind on earth shall be bound in heaven" (Matt. 18:18).
The word that you extract from Humani Generis also comes from a Pope and that word is already applied to Mary's Immaculate Conception which is also a Dogma.
ENCYCLICAL HUMANI GENERIS OF THE HOLY FATHER PIUS XII http://w2.vatican.va/content/pius-xii/en/encyclicals/documents/hf_p-xii_enc_12081950_humani-generis.html
There's is no impediment for Pope Francis to proclaim it a Dogma using the words "the soul was immediately created at the moment of conception".CCC365 & CCC366 had a good explanation to support this. The only problem is, which is a very big problem is, it will exclude Jesus the Author of Life.
Council of Nicea decreed Jesus was not created but "begotten" co-substantial with the Father and the Holy Spirit.Light from Light and God from God.
For it to become acceptable as Dogma the wordings must include the humanity of Jesus that was offered to all mankind for the Salvation of souls.
My suggestion would be like this to include the human but divine soul of Jesus Christ;
"All souls was immediately INFUSED at the moment of conception or at the moment it was formed".
I used the word "formed" also, so as not to forget our First Parents who are "formed" by God.
Genesis 2:7 New King James Version (NKJV)
"And the Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living being.
If the Theologians can accept the word "formed" as similar to "conception"
as Jeremiah also used the word "formed" by God.
"Before I formed you in the womb..." (Jeremiah1:5)
Therefore, Adam & Jeremiah was both "formed" by the Creative Hand of God.
It is also noteworthy to ponder the words of Archangel Gabriel to Mary;
"Behold, you will conceive and give birth to a son, and you shall give Him the name Jesus. "(Luke1:31)
Archangel Gabriel belong to the Choir of Chrubim like Lucifer who knows the Secrets of God, but Lucifer when cast down loses the Light of Truth. So, there is a Great Wisdom why Archangel Gabriel uttered the words "conceive" as he can simply omit that part and said, "you will bear or give birth to a son". But mentioning the word "conceive"it becomes a point of reference and understanding where life would begin and it is a Divine Truth as it was not spoken by man but by an Angel that hold the position as God Messenger.
Although Pope Francis Infallibility and Canonical Power & Authority plus charisma that the Holy Spirit is guiding his Divine Office can proclaim it, I wholeheartedly believe that He will avoid declaring it a Dogma much more the Holy Spirit will inspire him to bind all the faithful into that decree in these Time of Mercy.
Proclaiming this as a Dogma would send a lot of people to Hell as Abortion was being practice by millions of people and since a Church decree is bound in Heaven, the Just Punishment of God to all guilty souls will definitely be terrible as God explicitly said what punishment awaits those who kill and murder a life that God gave to every human being.
Fortunately, the Holy Spirit inspiration to Vatican II New Evangelization Mission in the Third Millennium is centered on the Divine Mercy. So this powerful Dogma although will convict and tied the hands of all catholic involve in the practice or force to make a choice on abortion to face a clear ex-communication even automatic ex-communication.
St.John XXIII opening the Vatican II, St.Pope Paul VI issuing Humane Vitae and St.John Paul Evangelical Vitae and as the instrumental person to revive the Divine Mercy revelation to St.Faustina and Pope Emeritus BXVI following the path of Divine Mercy and most especially now that Pope Francis is magnifying the Divine Mercy transforming the Church into a field hospital will not proclaim it a Dogma to avoid ex-communicating millions of souls worldwide and invite the grave punishment that God decreed on all who violates the 5th Commandment.
In closing, Pope Francis gave us his powerful reflections in these end times with this phrase;
"The Divine Mercy is INFINITE but the Time of Mercy is NOT."
