Human Beginnings and Endings

This series of posts is nearing the “midterm” point of the course on Summa contra Gentiles, Books II–III. Here is a collection of posts thus far:

  1. The Polyvalent Hierarchy of Wisdoms (ScG, I.1–8, II.1–5, et al.)
  2. God’s Power and Creative Act (ScG, II.6–27)
  3. The Possibility of An Eternal World (ScG, II.28–38)
  4. The Cosmos as Total Object of Creation (ScG, II.39–45)
  5. The Unity of the Human Person (ScG, II.56–72)

In the next three posts, we will cover ScG, II.73–90, continuing our study of the human person in the created order of the universe. Previously, Aquinas had argued painstakingly concerning the unity of the human being while alive—material body and  subsistent soul—against dualistic and materialistic options. This “middle case” now over, there remain the two endpoints of human life: conception and death. He now explores these two termini, where his account pushed to its limits, both philosophically and scientifically in discussing our own limits. 

Apart from the intrinsic philosophical interest of these subjects, we have discussed previously the idea that getting the truth about human nature right is crucial for various truths of the faith. Another reason for such care in these chapters is to be able to know, in a theological modality, about the human nature of Christ; e.g., note Apollinaris (and Apollinarism) at the end of ScG, II.86. (“A Christological theory, according to which Christ had a human body and a human sensitive soul, but no human rational mind, the Divine Logos taking the place of this last.” See “Apollinarism” at New Advent, Catholic Encyclopedia.)

These chapters illustrate the ways in which adequate metaphysics, philosophy of nature and science, along with accurate scientific data, or lack thereof, can inform theological inquiry. Consider the bioethical implications: When does a human person come into existence? When is the moment of death? Lastly, there are the questions of the post-mortem state—what sort of being or activity does a “disembodied soul” have?—as well as about bodily resurrection. We continue with:

  1. a review of the text, and final notes about Arabic psychology;
  2. consideration of the end of the union of body and soul;
  3. review of the discussion of the beginning of the union of body and soul;
  4. concluding comments on this topic;
  5. some parameters and limits of the discussion about the beginning of human life;
  6. the central principles and why Aquinas holds them;
  7. Aquinas’s medieval embryology and its flaws (both the more and less obvious);
  8. a reintegration of good philosophy with good science;
  9. some conclusions concerning the beginning of human life;
  10. review St. Thomas’s arguments that the human intellectual soul survives death;
  11. elucidate how the post-mortem intellectual soul can act;
  12. survey the landscape of a contemporary Thomistic debate about the post-mortem soul;
  13. show that the post-mortem intellectual soul is not a person, but a person in virtute;
  14. discuss what can be established philosophically about bodily resurrection;
  15. and offer some conclusions.

This post covers §§1–4; the next post §§5–9; a final post §§10–15.

7.1. An Overview of ScG, II.73–90, and a Farewell to Arabic Philosophical Anthropology

The text might be outlined as follows.

Our points of interest arise after a final consideration of Averroes, Avicenna, and their readings of Aristotle. In ScG, II.73, St. Thomas produces an extended, ten-part dialogue with Averroes’s position that the possible intellect is a separate substance. Many arguments we have seen before, but these seem to be the final blows. Here’s a shortened version:

  • Averroes: There is only one possible intellect for all humans.
  • Thomas: But this means that the intellectual substance is not a form, and besides, there would then be only one human being (through this one intellectual substance). Rather, “the form of this individual man is his intellective soul.”
  • Averroes: Well, maybe there are many different human individuals because they have separate sensible souls, but there is still only one intellectual principle.
  • Thomas: “If this man has a distinct sensitive soul from that man’s, and yet not a distinct possible intellect, but one and the same, it will follow that they are two animals, but not two men.”
  • Averroes: No, because “the possible intellect comes into contact with us by its form” insofar as it is joined to our sense experience, our phantasms. Thus, we are more than animals, and so “the possible intellect is individualized in different subjects not by reason of its substance, but by reason of its form.”
  • Thomas: I’ve already answered this (II.59), but let’s grant that it works. Because these phantasms are only in the sense powers, only in potency, are activities and not forms, and, besides, are many in number and they “do not always remain the same in one man, but some come anew while other previous ones pass away,” we are not specifically human in this way. We would still be animals.
  • Averroes: What I meant was not the phantasms as such, but, rather, “that this man derives his species . . . from the powers in which the phantasms reside—namely, those of imagination, memory, and cogitation.”
  • Thomas: Well, “still the same impossibilities follow.” For instance, this seems to imply that, because these powers are not in continuous operation, we would be only intermittently human, since the operation of these powers insufficiently continuous to keep us being human. And even if you avoided this absurdity (and others), the habits of science are in the intellect, and so everyone would have the same knowledge. Which is not the case.
  • Averroes: But the habits of science could be in the cogitative power, which is a sense power. So, different people would have different intellectual habits based upon that individual power.
  • Thomas: But the cogitative power is a sense power, and it cannot hold universal knowledge.
  • Averroes: The cogitative can do this because it is responsible for the disposition or promptitude of cogitating broadly speaking. Universals are still in the one, separate intellect.
  • Thomas: But this disposition in the cogitative power is not an intellectual habit, but a sort of preparation for an intellectual habit. So, even if we prepare our sense powers for such knowledge, the actual intellectual knowledge is in the possible intellect for all time. It seems, then, that “we shall come back to Plato’s opinion that we do not acquire knowledge from the senses, but that we are awakened by them to the recollection of things we knew before.”
  • Averroes: Well, ideas are eternal in the intellect, but they are ever new in the phantasms in each person.
  • Thomas: That’s an interesting distinction, but does it work? This would mean that the eternal depends upon the temporal for its own perfection. And, since the intelligible species are already preserved in the intellect, it would be pointless for that intellect to think about them again in the phantasms, it would be a sort of redundancy. So, the possible intellect does not need us, but we still need it!
  • Averroes: But your own view seems to require this conclusion and share the same weakness as my view. Once the individual’s intellect learns, it does not need the body anymore for knowledge. 
  • Thomas: Not necessarily, because the intellect needs the phantasms in different ways before and after it acquires knowledge. “For before, it needs it in order to receive from it the intelligible species; hence it stands in relation to the possible intellect as the object moving it. But after the species has been received into it, it needs the phantasm as the instrument or foundation of its species: hence it is related to the phantasm as efficient cause.”—Besides, you haven’t answered the argument that we would know everything by being in contact with this separate intellect.
  • Averroes: “We do not understand by the possible intellect, except insofar as it is in contact with us through our phantasms. And since phantasms are not the same in all, nor arranged in the same way, neither is whatever one person understands [also] understood by another.”
  • Thomas: “This reply cannot wholly avoid the difficulty, . . . for we observe that when we have once received knowledge of a thing, it is in our power to consider it again at will. Nor are we hindered on account of phantasms, because it is in our power to form phantasms adapted to the consideration that we wish to make.” So, I would only have to will it to know anything. But this does not happen.

Similarly, Avicenna’s position undermines the human experience of knowledge, learning, and being changed and benefitting from having learned. (So, II.75 considers what teaching actually is.) Aquinas is consistently concerned with finding a complete account of the human being based upon the complete range of our experience. We have all that we need, naturally, to be human:

If, then, the active intellect is a substance outside man, all man’s operation depends on an outward principle: consequently, he will not move himself but will be moved by another. Hence he will not be the master of his own operations, nor will he be deserving of praise or blame, and there will be an end to all moral science and political life, which is absurd.

ScG, II.76, last ¶

7.2. The End of Human Life? (ScG, II.79–82)

We will focus on the first three of these chapters: Aquinas’s positive arguments for the incorruptibility of the soul, and then how he addresses the negative arguments against his own view. 

As to the first, we should consider in class the sixth argument: Whatever is received is received in the mode of the receiver, and we receive actually intelligible things, and so, because of this, the human soul is incorruptible. 

We should also consider the ninth argument: The intellectual soul cannot corrupt by any of the known means of corruption (by contrary agent, by corruption of subject, or by defect of its agent cause). So, it cannot corrupt.

However, it is II.80–81 that is particularly fascinating.

The dispute over whether or not the human soul corrupts when the body does
Arguments that it does (II.80)Arguments against these (II.81)
1st: Matter numerically individuates; so, without matter (the body), the souls are no longer numerically diverse. Either they are annihilated or they coalesce into one soul.1st: There is a proportion between form and matter; so, they have being and unity correlatively. However, this depends upon whether form depends upon matter for being or not, and the human soul needs matter at the beginning but not at the end.
2nd: Forms can differ only by formal differences, that is, difference in kind; so, after death, our souls would be different in kind—but this must also be true before death, and thus we would be different in kind even now (not all “human”).2nd: The formal differentiation in question need not be a specific difference (e.g., this form of fire here and that one there are forms other that each other); in this case, the soul has a commensuration to its body, which is not a species-making difference.
3rd: An impossible infinity of souls would follow, for those holding the eternity of the world …3rd: Here, it is the eternity of the world that is the problem …
4th: If the soul did not corrupt when the body corrupts, then it would be accidentally joined to the body, as an independent being (so, the dualist problems would return).4th: This argument equivocates, because this definition of accident applies only to composites, not to essential principles. “Therefore, though it survives the body, [the soul] is united to it essentially and not accidentally.”
5th: A substance cannot exist without its proper operation; but all human soul’s activities need organs—even the intellectual ones; thus, without the body, it cannot act, and so it cannot exist.5th: We deny that no operations remain; thinking and willing remain. After death, the soul is akin to a separate substance: “Accordingly, though our act of understanding as regards its mode in the present life ceases when the body perishes, another and higher mode of understanding will take its place.”

Some notes on the above arguments:

  • The fifth objection has as its background an important principle, namely, that the human soul is the form of a naturally organic body having life potentially. By implication, the lack of organs seems to argue for the lack of being fully human.
  • The reply to the second argument introduces the fascinating idea that there is a certain commensuration or relationship between this soul and its proper body.
  • This relationship is strengthened in the reply to the fourth argument: If the soul is united to the body due to what it is, then is not the post-mortem state a state of violent existence, because the soul is not joined to what naturally completes its essence as form of … 
    • Wouldn’t being a “disembodied soul” be unfitting? existing in vain?
  • Do such difficulties disappear with the reply to the fifth argument? We learn that “since the human soul, as shown above [II.68], is on the boundary line of corporeal and incorporeal substances—as though it were on the horizon of eternity and time—it approaches to the higher world by withdrawing from the lower. Therefore, when it shall be wholly separated from the body, it will be perfectly likened to separate substances as to the manner of understanding and will receive their influence abundantly.”
    • In the course of adding the idea of immortality to immateriality and incorruptibility, “Thomas seems here to forget the pertinent Aristotelian comparison of the intellect to the owl in the light of day. . . .  Thomas creates ‘a new difficulty in the process of answering an old one.’” (Hibbs, Dialectic and Narrative in Aquinas, 94.)

7.3. The Beginning of Human Life? (ScG, II.83–5, II.87)

St. Thomas first considers a view that has come up before II.83–84: that human souls pre-exist their bodies. However, he now treats the position in its much more general version, in a way which includes thinkers besides Origen. (He avoids arguing against Averroes, again, but this chapter does have very interesting arguments against Plato; e.g., the 18th.) After laying out the opposing views, Aquinas marshals twenty-six separate arguments to make his case. Again, we see a connection between the importance of a thesis and the theoretical firepower the Angelic Doctor deploys.

One particularly interesting sequence of arguments is the 7th–11th, which successively eliminate various possibilities for coordinating the union of a pre-existing human soul with the generation of its human body: nature, choice, and God are all eliminated as options.

The 16th and 17th arguments that are to be noted: Either the soul needs senses or not; it seems that it needs them (a teleological argument); so, the human soul would not have been made without senses and hence sense organs and a body. If the soul does not need senses, then the soul beforehand knows all (Platonism results), and thus being united to the body is an impediment and unnatural. Aquinas follows this 16th proof with a very Dominican 17th proof:

Now man by all his well ordered and right operations strives to attain the contemplation of truth: for the operations of the active powers are so many preparations and dispositions to the contemplative powers. Therefore, the end of man is to arrive at the contemplation of truth. For this purpose, then, was the soul united to the body: which is to be a man. Therefore, it is not through union with the body that the soul loses knowledge; on the contrary, it is united to the body that it may acquire knowledge.

As an aside, we might also wonder whether the reply to the third opposing argument (see II.84), about the human species in the universe, is compatible with the individual dignity of human persons.

While the topic of II.85 might seem a bit outlandish, Aquinas does note that some Catholic thinkers interpreted Genesis in such a way that we are made of the substance of God. But this idea of human beings made “after the image and likeness” of God, “indicates an imperfect image rather than consubstantiality.” Still, as we find out in II.87, the origin of human souls is directly from the causal power of God. The second argument might suffice for us, keeping in mind the notion of creation from earlier in Book II: The human soul has being per se (unlike other cases of composite substances, where the whole substance has being per se). Rather, in the human case, the composite substance has being by sharing in, as it were, the being of the soul. Thus, the human soul requires its own coming into being, and, since it is immaterial, this must be a production without prior matter: thus, by creation. Since only God can create, each human soul must be created by God. (Of course, the fifth argument is particularly poetic, especially for Aquinas.)

But what about the human body?

7.4. Remaining Questions about the Termini of Human Bodily Life

The last chapter in the reading, ScG, II.90, defends an idea that St. Thomas goes to much greater lengths elsewhere to explain. This is the idea that the human intellectual soul cannot be the form of just any matter or type of body. In II.90, the focus is particularly upon elemental matter or what we might think of as simpler compounds. That is, the work done here is more minimal.

In other texts, particularly in Disputed Questions on the Soul, q. 8, St. Thomas asks “Whether the rational soul should be united to a body such as man possesses.” He argues as follows:

Since matter exists for the sake of form and not vice versa, we must discover, on the side of the soul, the reason why the body should be united to it. . . . Therefore, if the human soul is capable of being united to a body, because it needs to receive intelligible species from things through the intermediary of the senses, then the body, to which the rational soul is united, must be one which can most adequately present to the intellect those sensible species from which are derived the intelligible species existing in the intellect. Hence the body to which the rational soul is united must be best disposed for sensory operation. . . . if anyone also wishes to examine the particular dispositions of the human body, he will find them ordered to this end, that man may have the best sense. Therefore man, in proportion to his size, has a larger brain than any other animal, because a good disposition of the brain is necessary for the good condition of the internal sentient powers, namely, the imagination, the memory, and the cogitative power.

This sort of reasoning goes a bit beyond the appeal to “soft flesh and a delicate touch,” and stands as a medieval precursor to evolutionary biology’s investigations into the origins of the human brain and how its specific structure and function are necessary conditions for human cognition and language. (See Francisco Aboitiz, A Brain for Speech: A View from Evolutionary Neuroanatomy (London: Palgrave Macmillan, 2017), and see also Nicanor Austriaco, O.P., “Defending Adam After Darwin: On the Origin of Sapiens as a Natural Kind,” American Catholic Philosophical Quarterly 92, no. 2 (2018): 337–52 (, and Marie I. George, “Aquinas’s Teachings on Concepts and Words in His Commentary on John Contra Nicanor Austriaco, OP,” American Catholic Philosophical Quarterly 94, no. 3 (2020): 357–78 (

Thus, II.90 is really illustrating that there is a proportion between matter and form, or, more specifically, between what human matter must be, given what the human form actually is. This idea is at the core of the more controversial chapters still to be discussed.

Aquinas’s Embryology and the Beginning of a Human Person

The really puzzling and perhaps shocking chapters are II.86 and II.88–89, and at two levels (at least): 

  • First, the scientific details of Aquinas’s account are lacking, and thereby seem to undermined his philosophical principles as applied to this case. 
  • Second, the philosophical result—we are not human beings at conception—seems incompatible with Church teaching against abortion.

The second is more readily dealt with: Aquinas himself thinks that abortion at any stage is a grave evil, while the precise nature or being of the embryo or fetus at a given point would modulate the moral species of this evil act. (For instance, ST, IIa-IIae, q. 68, a. 8, ad 2: “He that strikes a woman with child does something unlawful: wherefore if there results the death either of the woman or of the animated fetus [puerperii animati], he will not be excused from homicide, especially seeing that death is the natural result of such a blow.”) The first point of difficulty is where we must carefully sift through how philosophical ideas intermingle with scientific inquiry and discoveries. 

Aquinas’s explicit account of human embryogenesis has been generally rejected because of its dependence upon medieval biological information. A number of scholars, however, have attempted to combine Aquinas’s basic metaphysical account of human nature with current embryological data to develop a contemporary Thomistic account of a human being’s beginning. Some Thomistic scholars argue that an early-term embryo lacks the necessary intrinsic qualities to be rationally ensouled until it reaches a certain point in its biological development [delayed hominization]. Others contend that there is nothing about an embryo’s biological nature, from the moment the process of fertilization is complete, that disallows its being informed by a rational soul [immediate hominization].

Jason T. Eberl, The Nature of Human Persons: Metaphysics and Bioethics (Notre Dame, Indiana: University of Notre Dame Press, 2020), 147.

Again, the reason why this is Aquinas’s own conclusion has to do with how form and matter are principles of the human person, and how he has developed this understanding in opposition to both materialism and dualism:

The basic metaphysical principle Aquinas employs in this account is that a rational soul does not inform a physical body unless the body is properly disposed for that type of soul. The requisite disposition is the body’s having sense organs and a brain capable of processing sensory information so that the mind may abstract intelligible forms. A body disposed in such a way does not seem to exist immediately after fertilization but only after first a vegetative embryo and then a sentient fetus have existed. Aquinas thus concludes that a living, sentient, and rational human being does not begin to exist until some point well after conception.

Ibid., 148.

This is also not the only “basic metaphysical principle” involved in this controversy. We will examine the debates about “hominization,” which involve weaving fundamental principles with scientific data, and the attempt to provide an updated Thomistic philosophical embryology, in what follows.

Aquinas on Death and After Death

There are also (at least) three layers when it comes to the other terminus of a human life:

  • First, when does a human being die? When does the soul no longer inform the human body?
  • Second, what mode of being and operation does the human soul have post-mortem?
  • Third, how do we solve the problem of the unnatural existence of the post-mortem soul?

Due to time constraints, we will not address the first question, concerning the event of death (ontologically and clinically), albeit this is a very important question in contemporary bioethics, and does in fact depend upon the principles we are discussing in these chapters. (See Nicanor Austriaco, O.P., Biomedicine and Beatitude: An Introduction to Catholic Bioethics, 2nd ed. (Washington, DC: The Catholic University of America Press, 2021), 262–309, as well as Eberl, The Nature of Human Persons, 172–207.) Rather, we will discuss the second and third topics. 

As to the second question, concerning the state of being and activity of the post-mortem soul, it seems that the intellect’s activities would be hindered by the lack of bodily organs. Is Aquinas’s answer in ScG, II.81 sound? He did nuance his view at various times in his career. This will lead us to consider a contemporary debate among Thomists: the survivalists vs. the corruptionists. While both sides maintain that the human soul survives death, the question is whether or not the separated soul is a person or not. (Remember that, according to the classic definition of Boethius, a person is an individual substance of a rational nature.) The survivalists say “Yes! And yet …,” while the corruptionists say “No! However …”

The third question will lead us to focus on another theologically relevant issue: the knowability and reasonability of the bodily resurrection. Here is a relevant text from St. Thomas:

If the resurrection of the body is denied, it is not easy, rather, it is difficult, to sustain the immortality of the soul. For it is clear that the soul is naturally united to the body and is departed from it, contrary to its nature and per accidens. Hence the soul devoid of its body is imperfect, as long as it is without the body. But it is impossible that what is natural and per se be finite and, as it were, nothing; and that which is against nature and per accidens be infinite, if the soul endures without the body. And so, the Platonists positing immortality, posited re-incorporation, although this is heretical. Therefore, if the dead do not rise, we will be confident only in this life.

St. Thomas, Super I Cor., c. 15, lect. 2, n. 924:

Can we prove philosophically that the body will be resurrected? Or, must the philosopher—analogous to the question of the temporal origin of things—only wonder, awaiting a revealed resolution?

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