Rather, the complexity of the embryo together with its specifically human character not only argues against the existence of a non-spiritual soul, but argues for the existence of a spiritual soul. For, by the principle of sufficient reason, the complexity and the specifically human character of the body must be governed by a form and derive from a principle which correspond to them. Now the form and the principle of a living thing is the soul, and the soul which corresponds to the said complexity and character is the human soul, a spiritual soul. There are no scientific grounds for holding that this principle resides in the molecular structure itself.
It may be objected here that the form of complexity necessary for the existence of a spiritual soul is an organic and not merely a molecular complexity. As an expert in this philosophical field Professor Horst Seidl remarks in the book Der Mensch als Gottes Ebenbild: ‘Nach einer breiten Tradition gehört es zum Wesen des Geistes, nicht organgebunden zu sein. Sein ‚Organ’ oder ‚Träger’ ist das sensitive Prinzip mit seinen Funktionen. Dieses Prinzip kann aber erst an einem Mindestorganismus seine sinnlichen Funktionen ausüben: According to a wide tradition, the spiritual soul is essentially independent of organic structures. Its organ, or subject, is the sensible principle together with the latter’s functions. This principle however requires a minimum organic structure for the exercise of its sensitive functions.
In reply, the complexity of the embryo is sufficient to prove the complexity of the respective soul; the fact that the complexity of the embryo is not organic excludes not the presence of this soul (which is anyway able to exist altogether independently of matter, e.g. after death) but only its organic functioning.
There is a second reason for positing the existence of a spiritual soul from conception, which is namely the organic development of the living being in question from conception until death. This organic development which accounts for ‘every detail of human development’ (see above), this unity and identity over time, requires a principle which itself possesses unity and identity over time. In later stages this principle is the spiritual soul; since it possesses unity and identity over time, it follows that it is a principle of the living being in question also in the earliest stages of its existence.
In the case of identical twins, a fertilized ovum in the early stages of pregnancy splits into two identical ova. This phenomenon is sometimes taken as the basis of such an argument as the following: the spiritual soul is simple and cannot split; the non-spiritual soul by contrast can split. It is thus reasonable to assume that the soul which animates the splitting ovum is a non-spiritual soul.
In reply to this argument it must be admitted that the spiritual soul cannot split, but that this does not exclude the possibility that the original fertilized ovum is animated by a spiritual soul. Let us now consider in brief certain theses that allow for this possibility:
When the division takes place, the original spiritual soul passes to one of the twins, whilst a new spiritual soul is infused into the other. One difficulty about this thesis is the lack of symmetry with regard to the twins on the spiritual level. While on the physical level there is a symmetry: one object splits into two objects, on the spiritual level there is an asymmetry: the spiritual soul survives in one identical twin, but a new spiritual soul is infused into the other.
A second thesis, which allows for symmetry on the spiritual level, holds that when the division takes place, the original fertilized ovum perishes and its spiritual soul leaves it, whilst a new spiritual soul is infused into each of the resulting twins.
Yet both this latter thesis and the former thesis are prey to a difficulty which may be described as follows: the spiritual soul is a principle of unity for the body it animates. In order for division to take place in a body animated by a spiritual soul, there must be a principle of division that overrides the principle of unity. But in order for the principle of division to override the principle of unity, it must be a higher principle, but there is no principle (at least on the human level) which is higher than that of the spiritual soul.
A third thesis holds that the division is caused by the (‘cloning’) action of a second spiritual soul taking a part of the first living being and forming it into a new living being. This thesis is not prey to either of the objections above, for there is symmetry neither on the physical nor on the spiritual level, and the first living being is divided not by a principle intrinsic to itself, but by a principle extrinsic to itself, namely the operation of a second spiritual soul.
This third thesis explains the division of the fertilized embryo into identical twins at least as well as the thesis which posits the existence of the non-spiritual soul. In conclusion then, the phenomenon of identical twins does not provide grounds either for doubting the existence of the spiritual soul from conception or for believing it.
To draw to a close this discussion of twins, let us briefly consider the phenomenon of ‘recombination’. Here two twins fuse together or ‘recombine’. If the twins are informed by non-spiritual souls, the explanation is both simple and symmetrical, since the (embodied) non-spiritual soul, being merely a function of the matter it informs108, can both split and combine with another non-spiritual soul. If by contrast the twins are informed by spiritual souls, there is no simple nor symmetrical explanation. For since the spiritual soul (whether embodied or disembodied) is itself simple, it can by definition neither split into two souls, nor can two such souls combine into one.
It is however possible to explain recombination in the case of the spiritual soul, by positing that one twin absorbs the other into itself. Such a phenomenon would be comparable to the phenomenon of splitting expounded above, on the basis that a person at the early stage of his development is such that:
1) a second spiritual soul may take part of his matter for creating a new person, thus causing a split from one person to two; and that:
2) a second spiritual soul (this time embodied) may take the whole of him (thereby destroying him as a person) as matter for enlarging its own dimensions, thus causing a brought into existence by certain corporeal agents.’
Summa Theologica I 118 a 1. ‘The sensitive soul …[is] naturally fusion of two persons into one.
This theory is no more than a hypothesis but is sufficient to show that the phenomenon of recombination does not necessarily require the existence of a non-spiritual soul.
To summarize this section we conclude that the complexity and the human character of the embryo from conception argues for the presence of a spiritual soul and therefore of the person as well, and while this cannot be ascertained by empirical ‘data’ (cf. the passage quoted above) the best available scientific evidence points in this direction.
In support of this thesis Dr. Ott remarks: ‘The newer Christian philosophy almost generally expounds the viewpoint that the creation and infusion of the spiritual soul coincides with the moment of conception.’ As evidence of this viewpoint, Dr Ott and others refer to the declaration of Innocent XI in 1679 in which he condemns the error (35) that: ‘It seems probable that every foetus (as long as it is in the womb) lacks a rational soul and begins to have the same at the time that it is born; and consequently it will have to be said that no homicide is committed in any abortion.’
Let us proceed briefly to expound the difficulties inherent in the theory of the later infusion of the spiritual soul.
Those that hold that the body is informed at conception by a non-spiritual soul are obliged to posit the existence of a being which consists of a human body (as science shows) and a non-human soul (because the human soul is of a spiritual nature). But this thesis has two flaws, for in positing such a hybrid entity:
1) It offends against the first principle of any sound anthropology: that man is a psychophysical unity: in the perennial philosophy this means that he is the unity of (human) body and (human) soul: corpore et anima unus. (The Aristotelian-scholastics do not offend against this principle because they maintain that both the body and the soul of the embryo are non-human.)
2) It offends against the principle of sufficient reason, for since the soul is the principle of the body, it must correspond to it in its nature: in other words, it must be of the human type, therefore spiritual.
Moreover to call this putative being a ‘potential person’ as does Professor Seidl for instance, on the basis that he possesses the physical attributes of human personhood and is ordained to receive the spiritual soul and thereby to become an actual person (p. 44ff op. cit.), is inaccurate, for this putative being is not a potential person in the full sense since he lacks an element essential to personhood, namely the human soul.
An adherent of this thesis has additional difficulties in resisting the theological arguments above, e.g. that which pertains to the Immaculate Conception (which is the argument most analogous to the issue of human personhood in general). He is forced into one of the three following positions: the first is that the conception in question was that of a potential person. And yet when Bl. Pius IX declared that the Blessed Virgin Mary was ‘preserved Immaculate from all stain of Original Sin’, he was clearly speaking of the person in the usual sense, in the full sense, of the term: he is speaking of the person as the composite of body and soul.
The second position is that the moment of the infusion of the spiritual soul or ‘animation’ is the moment of conception in the proper sense; the earlier event commonly called ‘conception’ is in fact merely an initial fertilization. This is however contrary to the common understanding of conception: clearly Bl. Pius IX shares this understanding rather than the view of conception prevalent among scientists of the Middle Ages.
The third position is to claim that the Blessed Virgin Mary enjoyed as one of her unique privileges the infusion of the spiritual soul at conception. But there is nothing in the Dogma of the Immaculate Conception (or in any other Marian Dogma) that entails that this conception took place earlier than any other.
The original author of this blog passed away in July of 2016. RIP Father Carota.