29 March 2014

A look at the body-soul relationship and the notion of "corpus purus"

This article was originally written in June 2013.

In this article I will look at some issues regarding the nature and creation of man itself, a creation that is both evolutionary as it refers to the body and by way of direct divine intervention as it refers to the spiritual soul.  This last statement clearly reflects a specific notion of the nature of human soul, a notion which is in accordance with the Magisterium of the Catholic Church.  A good review of historic and current positions on this subject is in [1].  For this article, I will only consider two positions:

For animals, including hominins right up to the moment of man's creation, Mario Bunge's emergentist materialism, which is monistic with respect to substance.  While this use of Bunge's position was not what he had in mind, since he focused on the human mind, he would probably agree that it also applies to the far more primitive animal psyche. And on the Catholic side, even the most traditional neo-scholastic thomist would concede that emergentist materialism correctly describes the nature of a chimpanzee or of any other animal (as in fact it agrees with the 14th of the famous 24 thomistic theses).

For humans, hylomorphic dualism, which posits that the human body is animated by a spiritual soul, so that spirit and matter, in man, are not two natures united, but rather their union forms a single nature.  Additionally, every spiritual soul is created immediately by God - it is not "produced" by the parents - and also is immortal: it does not perish when it separates from the body at death.  It is easily seen that this position reflects the orthodox doctrine of the Catholic Church, as the text has been directly copied from CCC # 364-366, (and it also agrees with the 15th of the famous 24 thomistic theses).

I directly discard the so-called "strong emergentism" of Ruiz de la Peña, which holds that the spiritual substance (not just faculties or properties) proceeds from matter by way of self-transcendence of the latter (el alma, "materia que se autotrasciende"), or, in words of Martínez Sierra, that the spiritual principle appears as a "blooming" ("efloración") of matter.  Because, while at first sight it is arguable whether spiritual properties such as intellect and free will can arise out of matter, it is plainly evident that a spiritual substance - much less one able to subsist after the dissolution of the body - cannot appear as a result of a process of self-transcendence of the material, nor can it "emanate" from other limited spirits, but can only be breathed from Above, i.e. created immediately by God.

Given the subject under study, it is mandatory to take into account this dogmatic definition of the Ecumenical Council of Vienne, decree 1:

"Moreover, with the approval of the said council, we reject as erroneous and contrary to the truth of the catholic faith every doctrine or proposition rashly asserting that the substance of the rational or intellectual soul is not of itself and essentially the form of the human body, or casting doubt on this matter. In order that all may know the truth of the faith in its purity and all error may be excluded, we define that anyone who presumes henceforth to assert defend or hold stubbornly that the rational or intellectual soul is not the form of the human body of itself and essentially, is to be considered a heretic."

Therefore I solemnly profess that the rational or intellectual soul is, of itself and essentially, the form of the human body.

Now I will perform a simple thought experiment that will show, among other things, the importance of emphasizing "human" as adjective of "body" in the above statement.

Focusing now on an the case of an animal, as I said before it is clear that its nature is correctly described by Bunge's emergentist materialism, so that we can combine the concepts from this theory with those from thomism and state that the sensitive soul which is the substantial form of the animal is an emergent property of the matter of its body, just as the vegetative soul which is the substantial form of a plant is an emergent property of the matter of the plant's body.  It is important to note that an animal has only one soul, the sensitive, which includes the powers of the nutritive or vegetative soul of a plant.  In Aquinas' terms, the sensitive soul, being a higher form, contains virtually the nutritive soul, so that itself alone does whatever the lower form does in plants (ST Ia.76.4 & 76.6.ad 1).  From the perspective of emergentist materialism this view is clearly correct: as a living being's substantial form is an emergent property of the matter of its body, each living being has only one substantial form which reflects the nature of its body, the higher the being the more functional the form.

Let's now go backward in time to the moment of the creation of human beings, when God infused a spiritual soul in two individuals, and from that time on, in their descendants.  But first a small digression: the specific time of the creation event, and the consequent particular species in the evolutionary line leading to Homo Sapiens on which that event occurred, is a debatable issue, so that one could in principle pick for biblical Adam any of those species that are unanimously considered by scholars to belong to the genus Homo [2], which I list below together with their estimated time of appearance and cranial capacity:

- Homo Ergaster (1.75 Ma, 850 cm^3). Colateral offspring: H. Erectus.

- Homo Antecessor (1 Ma, 1000 cm^3). Colateral offspring: H. Heidelbergensis and from that H. Neanderthalensis.

- Homo Rhodesiensis (0.6 Ma, 1300 cm^3).

- Homo Sapiens (0.2 Ma, 1450 cm^3).

Of these, Homo Sapiens is clearly the best choice for two reasons:

- It allows matching biblical Adam to Y-chromosomal Adam, who according to a current plausible estimation could have been contemporaneous with Mitochondrial Eve at precisely 0.2 Ma. [3]

- It allows matching the time of its appearance with the origin of language according to two recent studies [4] [5].

Back to the creation of human beings, at this point I need to use some notation and concepts that I introduce in the article "Creation of man. Concordance between science and Genesis account" in this blog. The notation is:

t-humans = true humans = theological humans = metaphysical humans = with an infused spiritual soul

q-humans = quasi humans = biologically identical to t-humans but without an infused spiritual soul

immediate-previous-hominins = individuals of the immediate ancestral species to q-humans/t-humans

Using that notation, there are two possible cases for the creation of the first two t-humans, Biblical Adam & Eve:

1U: Spiritual-only Upgrade

In this case q-humans were brought into existence by way of biological evolution. When there were at least several thousand q-humans around, God created Biblical Adam & Eve by infusing in two q-humans a spiritual soul, so that they were biologically identical to the surrounding q-humans, differing only by having been infused a spiritual soul.

2U: Physical & Spiritual Upgrade

In this case there were no q-humans, and God created Biblical Adam & Eve by producing in two individuals engendered by immediate-previous-hominin parents both a physical and a spiritual "upgrade": at the biological level, at least a brain-enhancing macro-mutation, plus the infusion of a spiritual soul.

In either case, Biblical Adam & Eve are the only t-humans for which infusion of a spiritual soul could have occurred at any time after birth (and in my personal opinion, it probably occurred after they had become independent of their respective q- or immediate-previous-hominin parents). In the case of all their descendants, infusion of the soul took place at conception.

As described in the mentioned previous article "Creation of man:...", before the end of 2012, when then-current scientific data pointed to mitochondrial Eve having lived 30 ka earlier than Y-chromosomal Adam, creation case 1U and its associated assumption that q-humans were viable as animals was required for a conceptual framework consistent with both that timing discrepancy and the "historical Adam" position.  At the end of 2012 a new study was published that pushed back the estimated time of Y-chromosomal Adam, so that according to a plausible estimation he and mitochondrial Eve could have been contemporaneous. [3]  As a result, it is now possible to match current scientific data with the "historical Adam" position using either creation case.  Thus, there is no constraint from that side for favoring one position over the other.

Now, each case raises interesting issues related to both thomistic anthropology itself and the nature-grace controversy.  Let`s start with creation case 1U.  It is easily seen that it is based on two implicit assumptions:

Assumption 1: q-humans, i.e. beings organically identical to humans but without an infused spiritual soul, are viable as animals.  Of course they would not be able to do abstract thinking, have elaborate language, do art, practice agriculture, build cities, etc., but the point is that their having a highly complex central nervous system (CNS) did not cause them to just collapse, collectively or even individually, because of their lack of a spiritual soul.  I call this assumption the "corpus purus" hypothesis, as it is analogous to the "natura pura" hypothesis.

The denial of this assumption has a major implication: that an animal with a complex enough CNS rigorously requires being infused a spiritual soul to be viable even at the animal level, or, paraphrasing Pius X's Pascendi Dominici Gregis 37, "that there is in a sufficiently neurologically developed animal nature a true and rigorous necessity with regard to a spiritual soul – and not merely a capacity and a suitability for a spiritual soul".  We can see that this position is an exact analog of Lubacian intrinsicism, replacing:

sufficiently neurologically developed animal nature -> human nature

spiritual soul -> supernatural order.

Thus, if the opposite to the "corpus purus" hypothesis was the actual case, it could be viewed as a hint that God proceeded in the same way regarding human nature and the supernatural order, i.e. as described by Lubacian intrinsicism.

Assumption 2: it is perfectly compatible with God's infinite goodness not to infuse a spiritual soul to an animal that has a capacity and a suitability for it.

The denial of this assumption is indirectly related to the nature-grace controversy, in the sense that, if it is unbecoming to God not to infuse a spiritual soul to an animal that has a capacity and a suitability for it, it is also unbecoming to God not to elevate to participation in the divine nature a rational being that has a capacity and a suitability for it.

Regarding thomistic anthropology, it is important to note that, in creation case 1U, the existing q-humans before creation, being animals and not true humans, had as the substantial form of their bodies a sensitive soul that was an emergent property of the matter of their bodies.  In the case of biblical Adam and Eve, after they were created humans they had as the substantial form of their bodies their spiritual soul, as defined by the Council of Vienne.  But St Thomas Aquinas goes further by stating consistently that the infusion of the spiritual soul causes the previous sensitive soul to "perish", "be removed", "be corrupted", "fade away". (SCG II.89.11; ST Ia.76.3.ad 3; ST Ia.118.2.ad 2; QD de potentia III.9.ad 9; QD de spiritualibus creaturis III.ad 13; QD de anima XI.ad 1; CT 92)

Now, given that in case 1U the creation of Adam and Eve consisted just in infusing them a spiritual soul without making any physical modification in their bodies, how could it be that, according to thomistic anthropology, their bodies were no longer producing a sensitive soul? There are two possible solutions to this problem:

One possibility (b) is that creation case 1U is not viable, so that we have to turn to creation case 2U, which does not depend on either of those assumptions for its viability, although it is compatible with them.  In this case, a macro-mutation simultaneous to the infusion of the spiritual soul changed the working mode of the brain so that it was prepared to work under the spiritual soul.

Another possibility (a) comes from a more refined understanding of the position of St Thomas in relation to emergent materialism: the "sensitive soul" is not intrinsically identical with "the sensitive layer of emergent properties of matter" but a possible role of it, so that:

- when there is no spiritual soul, "the sensitive layer of emergent properties of matter" acts as an "end point" and therefore a "sensitive soul".

- when there is a spiritual soul, "the sensitive layer of emergent properties of matter" acts as an "intermediate layer" which is no longer a "sensitive soul".

Thus the infusion of the spiritual soul does not cause the removal or corruption of the emergent properties of the brain, but a change of their role, so that they now become part of the aristotelian "matter" for which the spiritual soul is the "substantial form". I.e. the "human body" in the definition of Vienne is not just its constituent matter (in the modern sense, i.e. molecules) but organized matter plus its emergent properties. 

This is most easily visualized using the conceptual model of a layered system, such as those used in communications (like the OSI model) and computer systems.  In this model, the spiritual soul is a new higher layer that does not replace the sensitive layer but "plugs onto it from above".  A simple analogy would be the spiritual soul being the operating system and the sensitive layer the firmware, (or the BIOS when the operating system was old MS-DOS, because modern operating systems do not use the BIOS so that their case would be analogous to the thomistic position).  To note, the lower interface of the human spiritual soul, its capability to bind to the upper interface of the sensitive layer of a complex body, its "unitability" in Bonaventura's term, differentiates it from a pure spirit.

Now, in this analogy it is clear that the mode of operation of the sensitive layer is essentially different before and after the infusion of the spiritual soul.  Before the infusion it is an "end point" which receives "input" (sense data, etc.) from the body, performs some elementary processing of the data and generates "output" to the body (movements, etc.).  After the infusion, in contrast, it passes most sense input "upstream" through its upper interface to the spiritual soul (some sense input is probably still processed by the sensitive layer, like reflexes), and it is now the spiritual soul that processes the data in a much more advanced fashion and generates the "output" that is passed "downstream" to the sensitive layer. 

Thus there are two possible options:

a. The infusion of the spiritual soul is enough to make the brain switch its working mode so that its emergent properties are no longer an end-point ("a sensitive soul") but an intermediate layer.  In this option, creation case 1U was possible and "corpus purus" is a hypothetical possibility and it was actually the case before creation.

b. The brain itself must be created in such a way that it is ready to work as an intermediate layer beneath the spiritual soul, with the result that its emergent sensitive layer can no longer work in a stand-alone "end point" mode.  In this option, creation case 1U was not possible and "corpus purus" is not a hypothetical possibility.  Also, this option is conceptually analogous to de Lubac's intrinsicist position.


[1] Amo Usanos 2007. "El principio vital del ser humano en Ireneo, Orígenes, Agustín, Tomás de Aquino y la antropología teológica española reciente". Tesi Gregoriana, Serie Teologia, 148. Editrice Pontificia Università Gregoriana. Roma, Italia.

[2] Wood & Collard 2001. "The meaning of Homo".

[3] Wilson Sayres 2013. "Timing of ancient human Y lineage depends on the mutation rate: A comment on Mendez et al".

[4] Nichols 1998. "The origin and dispersal of languages: Linguistic evidence". In Jablonski, N.G. and Aiello, L.E., eds. 1998. "The Origin and Diversification of Language", pp. 127-70. (Memoirs of the California Academy of Sciences, 24.) San Francisco: California Academy of Sciences.

[5] Perreault & Mathew 2012. "Dating the Origin of Language Using Phonemic Diversity".

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