23 September 2021: The Nature of the Human Soul: the Arabic Tradition, Albert the Great, Thomas Aquinas and Latin Averroism.

The Nature of the Human Soul

Part One: Key Issues

NOTE: I generally try to distinguish Ibn Rushd who wrote in Arabic from Averroes whose writings are known were known by the Latin tradition in translation. I try to follow the account by Akasoy and Giglioni in Renaissance Averoism: Arabic Philosophy in Early Modern Europe (New York & London: Springer 2010), introduction pp.1-2:
Ibn Rushd, Muslim born in Cordoba, is “the renowned judge, physician and commentator of Aristotle” who died in 1198; Averroes is “the literary incarnation in translations and philosophical treatises of the Latin West;” “Averroan” and “Rushdian” refer to “any philosophical view that belongs directly to Ibn Rushd.”
NOTE: They also write this which is incorrectly phrased: “’Averroist’ refers to opinions held by any follower of Ibn Rushd in the Latin West during the late Middle Ages, the Renaissance and — though less and less frequently — during the seventeenth and eighteenth centuries.” Why is this incorrect? The Latin Averroists had no access to the Arabic writings of Ibn Rushd. Rather, they were followers of Averroes as available in Latin translation. This distinction must be made because of small but very significant mistakes of translation and of interpretation that led to bizarre Latin doctrines attributed to Averroes which were never part of the thought of Ibn Rushd.
Before proceeding, (i) I will succinctly review some key issues relevant to this discussion. (ii) After that I will provide an oral overview of what is commonly called Latin Averroism. There will be three parts to this: (a) A brief overview of the chief teachings of Latin Averroism, including an account of Albert the Great and its influence on Thomas Aquinas; (b) a brief account of Ibn Rushd on intellect and soul and how Averroes was generally understood by the Latins; and (c) a brief account of a multi-stage misunderstanding (1) of the Arabic text of Ibn Rushd’s Commentary on the Metaphysics of Aristotle by the translator Michael Scot and (2) of a phrase properly translated from Arabic by Michael Scot but improperly understood by Albert the Great who in that mistaken understanding was largely responsible for the attribution to Averroes of a complex array of doctrines about human knowing, the afterlife, the replacement of religion with philosophy, and even “Averroistic mysticism.” (See Kurt Flasch, Meister Eckhart. Die Geburt der « Deutschen Mystik» aus dem Geist der arabischen Philosophie, (Munich: C. H. Beck, 2006), draws on Parian lectures published in French in: D’AVERROES A MAITRE ECKHART. LA NAISSANCE DE LA «MYSTIQUE » ALLEMANDE ET L’ESPRIT DE LA PHILOSOPHIE ARABE (Paris: Vrin, 2008). The editors of this write: “Ce livre reprend le contenu des Conférences Pierre Abélard prononcees par Kurt Flasch en mai 2005 a la Sorbonne. Conformément aux principes de cette collection, nous leur avons laissé leur caractère oral. Les questions abordées dans ces leçons ont depuis été publiées en langue allemande dans Kurt Flasch, Meister Eckhart. Die Geburt der « Deutschen Mystik » aus dem Geist der arabischen Philosophie [Maitre Eckhart. La naissance de la « mystique allemande » de I ‘esprit de la philosophic arabe], Munich, C. H. Beck, 2006. Nous avons parfois choisi de compléter le texte des leçons à partir de cet ouvrage, mais nous n’en avons en aucun cas fait une traduction systématique. Par ailleurs, ces leçons offrent plus de citations textuelles, dont nous nous sommes efforces de donner la traduction. En appendice, nous avons traduit un texte dans lequel Kurt Flasch résume sa méthode de médiéviste.” P.7.)
Bianiak, M. 2010, THE SOUL-BODY PROBLEM AT PARIS, CA. 1200-1250. For the TOC of this book, use this Link.
Bazán, “On First Averroism and its Doctrinal Background,” OF SCHOLARS SAVANTS AND THEIR TEXTS Paris 1989
Bazan, The Human Soul- Form & Substance! Aquinas’ Critique of Eclectic Aristotelianism AHDLMA 1997
Bazán, “Was there ever a ‘First Averroism’?,” MISCELLANEA MEDIAEVALIA 27 2000
Bazán 2001, “Conceptions on the Agent Intellect & the Limits of Metaphysics,” in Nach der Verurteilung 2001
A. Gauthier, “Notes sur les débuts (1225-1240) du premier ‘averroîsme’.” RSPT 66 (1982) 327-74.
Salvador Gómez Nogales, “Saint Thomas, Averroès et l’Averroïsme.” In Aquinas and Problems of His Time, G. Verbeke and D. Verhelst (eds.), 161–177. Louvain: Leuven University Press, 1976.
Salvador Gómez Nogales, “En torno a la unidad del entendimiento en Averroes.” In Multiple Averroès. Actes du Colloque International organisé à l’occasion du 850e anniversaire de la naissance d’Averroès. Paris 20–23 septembre 1976, Jean Jolivet and Rachel Arié (eds.), 251–256. Paris: Les Belles Lettres, 1978.
Some valuable texts from last year’s course: https://marq-my.sharepoint.com/:f:/g/personal/richard_taylor_marquette_edu/ErCuBjo8-s9IiOwnN671tfYBt9-XMk-0OZDQNO8f-oDryg?e=EogTxG
The Problem of the Unity of Human Nature in Early 13th European Theology and Philosophical Theology.
The most influential of medieval Latin thinkers before 1225 on the nature of the human being as composite of soul and body was surely St Augustine. His conception was substantially Platonic or Neoplatonic largely influenced by the teachings of Plotinus. Augustine said that for knowledge we do not depend on the senses but rather the senses may prompt us to turn inward and through this movement to the interior we will find our true selves and also true knowledge. (This Platonic approach is also find in the Arabic tradition in al-Kindi who held we must turn to the transcendent for knowledge, not toward senses.) Something somewhat similar is found in Ibn Sina / Avicenna. For him we use sensation in this life to learn but the essences of things are found in the transcendent Agent Intellect. This is a doctrine derived in part from al-Farabi but ultimately from Plotinus who held for a hierarchy of One, Intellect (Nous), Soul and Nature. The true patria (homeland) of the human soul is found in Intellect and the rationality of our souls is linked to the lower parts of Intellect since our rationality contains intellectual powers. For Avicenna we must link to the transcendent intellect to have knowledge. For Avicenna, as we have seen, the human is a rational soul using the body as a tool. At death the body is discarded and the soul rises toward being with the Agent Intellect according to the level of understanding and personal intellect (possible or material intellect) it attained during bodily life. The souls then with the Agent Intellect know and worship God at the highest level for humans.
Before his death in ca. 1190 Dominicus Gunsissalinus with Ibn Daud (see https://pagines.uab.cat/gundisalvi/) translated the De Anima, Metaphysics and more by Avicenna from Latin into Arabic (see https://dominicusgundissalinus.wordpress.com/latin-translations/) Latin theologians were excited by the work of Avicenna and read it along with their knowledge of the teachings of Augustine. The idea that the human soul is per se rational and immaterial, living beyond the death of the body fit the teachings of Augustine and their Western Catholicism well. But the second or perhaps first most important event of Christianity is the promise of the resurrection of the dead. (Before that one would put the Incarnation of the Son of God, of course.) Resurrection is promised to all and is the proof of Jesus as the Christ. So, what about the body? Avicenna discarded it and made the rational soul the human self. But this issue stressed the theologians because Augustine’s own teaching did not handle it well, though, of course, he held the Christian doctrine of the resurrection of the body and the unity of the human being as body and soul in one. So Augustine’s reasoning about how the body is part of the whole human rather than it being the tool it was consider by Avicenna, made trouble for sound theological explanation. Magdelena Bieniak (PhD KULeuven) wrote a fine book on this: Bianiak, M., THE SOUL-BODY PROBLEM AT PARIS, CA. 1200-1250. Leuven University Press, 2010. Here is her table of contents:
[Pages from Bianiak, M 2010, THE SOUL-BODY PROBLEM AT PARIS, CA. 1200-1250-page1.pdf][Pages from Bianiak, M 2010, THE SOUL-BODY PROBLEM AT PARIS, CA. 1200-1250-page2.pdf][Pages from Bianiak, M 2010, THE SOUL-BODY PROBLEM AT PARIS, CA. 1200-1250-page3.pdf][Pages from Bianiak, M 2010, THE SOUL-BODY PROBLEM AT PARIS, CA. 1200-1250-page4.pdf]
As you can see, many theologians struggled with this. The question is this: Is the soul a substance in its own right and is the person a dual substance, body and soul? What is the relationship between the two?
Carlos Bazán has shown the Christian theologians had constructed the new conception of the human rational nature as that of a soul having two distinct powers, one of abstracting essences (the agent intellect) and another of receiving the abstracted essences. This doctrine, as Bazán has shown, was theorized before the texts of Ibn Rushd / Averroes were translated and available in Latin. The novelty of the doctrine is that it makes agent intellect a power of the individual human soul. Before this the history of intellectual understanding in the Aristotelian tradition, it seems that all thinkers held that this Agent Intellect is a transcendent source that in some way helps humans carry out intellectual abstraction by providing a power from outside. (On De Anima 3.5, see Shields Link. At Generation of Animals, 2.3, 736b27-28, Aristotle says that nous or intellect comes from outside.) This seems to be derived from Alexander of Aphrodisias, the most fully Aristotelian of the Commentators, though it is not fully clear that Aristotle himself held this.
As we have seen, Albert provided an account of the human soul as having two immaterial powers, agent intellect and receptive possible (‘material’) intellect. This view Albert attributed to Averroes in his 1242 De Homine, part of his Summa de creaturis, as we have discussed. Albert also mentions the other interpretation of Averroes, namely that the intellects are separate substances when he says that these are “in the soul” and adds, et non substantia separata, “and not separate substance.” Albert’s doctrine (incorrectly) attributed to Averroes and came to be known among 20th century scholars are “First Averroism.” And here Albert refuses to attribute to Averroes the (correct) doctrine that humans have intellectual understanding through a connection to two separately existing Intellectual Substances that are shared by all human kind. But that was in 1242.
Albert arrived in 1243-44 at the Dominican House of Study at Couvent St. Jacques in Paris. Thomas was there with Albert 1245-1248, then studied with Albert in Cologne 1248-1252. In about 1252-53 Thomas wrote In 1 Sent d. 8, q. 5, a. 2: Whether the soul is simple and also In 2 Sent. d. 17, q. 2, a. 1: Whether there is one soul or intellect for all human beings.
In 1250-52 Albert wrote the first Latin commentary on the Nicomachean Ethics of Aristotle with Thomas present with him in class and working with him in the preparation of this work while still in Cologne. In this work Albert makes it clear that he now understands the true doctrine of Averroes, that there are two separate intellectual substances (Super Ethica, pp.72A; 451B ff.) and speaks of there being one essence of soul for all human beings.
Thomas in In 2 Sent. d. 17, q. 2, a. 1: Whether there is one soul or intellect for all human beings provides a long account of the Arabic tradition mostly using the Long Commentary on the De Anima of Averroes (see my 2013 article). After attacking the view of Averroes, Thomas goes on to spell out his own teaching. That teaching is based on his own rereading of the Arabic tradition in Latin translation. But his teaching is fundamentally the same as what Albert wrote in the De Homine in 1242 with the correction that Albert made in his 1250-52 Super Ethica when Thomas was his assistant in Cologne.

Latin Averroism in Albert the Great: Oral remarks at class on monopsychism. Texts of Albert are those recommended 27 October 2020 by my colleague Henryk Anzulewicz, research professor at the Albertus Magnus Institut in Bonn: Super Ethics, pp.451-453.

Part Two: Let’s start over again.

An orderly analytical overview

The establishment of the Necessary Being in the metaphysics of Ibn Sina / Avicenna and the dependence of possible beings on the Necessary Being was a key argument for Aquinas to show that there is one God from Whom being or existence is received by all creatures.
The reasoning establishing the essence as quiddity expressed in a definition includes form and matter or form and supposit yields a conception of essence such that essence does not include existence. This is the essence-existence distinction in all beings other than the Necessary Being. This was taken from Avicenna by Aquinas.
3.1. In his De Anima Avicenna reasons that the human rational soul cannot know more than one intelligible essence at the same time. There is no intellectual memory to retain abstracted or received intelligibles. Abstracted intelligibles are recalled and used by humans through an ongoing connection to the Agent Intellect. Human knowing requires the collaboration of a transcendent Agent Intellect (where all the intelligible essences primarily exist) for attaining knowledge of essences and for retaining access to those intelligibles which a human being has come to know. This Agent Intellect provided the essences found in transitory things of the sublunary world which humans by the power of their rational souls can some to know. The Agent Intellect, then, is source of the natures of things of the world and scientific knowledge of essences requires the collaboration of the Agent Intellect. This collaboration is variously described as a uniting or joining (ittiṣāl) with the Agent Intellect or an emanation (fayd) from the Agent Intellect. The receptive intellect in the human rational soul is called the material intellect or sometimes in Latin the possible intellect.
3.2. In his Long Commentary on the De Anima, Ibn Rushd /Averroes reasons, as Aristotle seems to do in De Anima 3.5, that humans as intellectual beings must have a certain receptivity since they go from not knowing to knowing. In his context, reasoning established the necessity that the separate Material (scil. Receptive) Intellect had to exist to receive abstracted intelligibles brought about by the Agent Intellect and impressed on the Material Intellect, for these reasons: (i) all knowledge comes through the senses; (ii) knowledge of intelligibles is immaterial, not bodily; (iii) they could not be received into individual human bodily powers without being being particularized; and (iv) hence, they must have an intellectual subject into which they are received and retain. These intelligible essences are the basis for universals of scientific predication.
Aquinas followed Albert in agreeing with Averroes about immaterial receptivity. However, that receptivity could take place only in an intellect. So Ibn Rushd /Averroes asserted that there must be two separate intellects we access: the Agent Intellect helps us do abstraction to convert images in the cogitative and memory powers of the brain into immaterial intelligibles or intellectual concepts which can be used in predications and science, e.g. All human beings have intellectual understanding. But these intelligibles cannot be in the body and still retain their universality, as I said just above. So there must be an immaterial subject into which they are received. This subject for Ibn Rushd is the immaterial receptive Material Intellect. (This term is taken from Alexander of Aphrodias to denote receptivity, not materiality. No intellect can literally be immaterial.) So for Ibn Rushd all human beings share in one separate immaterial intellect called, ‘the Material Intellect.’ But the individual human beings have individual connections, so if you learn something, I do not learn it automatically without effort. But this does allow for a common unity of thought such that when I refer to horse and you refer to horse we are referring to the same intelligible concept and definition. Without this there would be no commonly known science.
Part Three: The Arabic Tradition
An introductory video on Avicenna is available at https://streaming.mu.edu/Watch/Yr2m5H4L
        We have studied the theories of knowledge set out by al-Farabi, Avicenna and Averroes. The foundational starting point for these thinkers is found in their conceptions of the nature of intelligibles in act. Insofar as human beings have knowledge of universals or intelligibles in act as necessarily an immaterial activity, this activity must have an immaterial subject in which it adheres. That is, following Aristotle, the existence of the activity or function is experientially prior and indicates the necessity of an immaterial soul as the source of the activity. Hence, our study of the soul is posterior to our study of human knowing.
         The most influential of the philosophers of the Arabic tradition for the thought of Aquinas on the nature of the soul are Avicenna and Averroes. But some words on al-Farabi are appropriate before we proceed to those other thinkers.
Some Remarks on al-Farabi, a review
In the account of his Risalah fi-l-‘aql and in some other works, al-Farabi followed Alexander’s account abstraction in a distinctive way by stressing that abstraction takes place thanks to something (a power of receptivity) provided to the human soul by the Agent Intellect. (Note he departed from Alexander regarding the identification of the Agent Intellect with God, perhaps an indication of influence of Themistius, a topic for further investigation.) For al-Farabi a human being realizes true substantiality when, after many abstractions, the human soul no longer needs the body and can think intelligibles without having to go through the process of abstraction. Precisely how this works he does not fully explain. But he does say that this is human fulfillment and happiness and also the meaning of the afterlife. At this stage the human immaterial rational soul, he tells us, rises to the level of the Agent Intellect. On this account human fulfillment is found in a transformation or realization or becoming of the human being as an immaterial human soul is now an eternal substance.
          The nature of the human soul and its relation to the body was a significant concern for all thinkers of the Abrahamic traditions because of intimations of an afterlife in the Old Testament and explicit promises of reward and punishment in a definite afterlife promised in the New Testament and the Qur’an. Discussions by philosophers drew on the Platonic tradition of dualism in which the human being was considered primarily as the soul and on the Aristotelian tradition in which the soul was understood to be form of the body and perishable with it, entailing that particular human intellect also perishes. The second position is implied by Aristotle and is found in the De Intellectu by the second century commentator Alexander of Aphrodisias (Alexander 1887 90.6.11, 1979 119; Cerami 2016, 173 ff.). The first position is found in the Paraphrase of the De Anima by the fourth century commentator Themistius (Themistius 1899 105 ff., 1973 191 ff., 1996 130 ff.) and in Neoplatonic thinkers. Both positions were presented in Arabic translations of Greek works. Aristotle himself had indicated that the intellect may be a distinct kind of soul different from those powers intrinsic to the body (De Anima 2.2, 413b26 ff.). This is a very important assertion that must be kept in mind.
The issue of the nature of the human soul for Avicenna, a review
          The most brilliant of the philosophers of the classical rationalist tradition of philosophy in the lands of Islam was Ibn Sīnā or Avicenna (d. 1037) who chose to follow late Alexandrian thought on the relation of soul and body. (Wisnovsky 2003, 2005) According to this tradition the soul was understood to be the perfection and end of the body per Aristotelem (De Anima 2.1-2) but not form of the body as something perishable with the body. The Alexandrian tradition provided reasoning affirming this and leading to the assertion that the human rational soul is the perfection and end of the body but not present in it as a perishable material form. In the opening chapters of the first book of his De Anima of the Shifa’ Avicenna uses the reasoning and language of Aristotle’s De anima 2.1 stating in chapter 6 that “the soul is the first perfection and, because perfection is a perfection of something, the soul is the perfection of something. This thing is the body.” (Avicenna 2007, p. 178) However, for Avicenna the rational soul is separate and not essentially bodily. In the immediately following chapter provides a pointer and reminder about the nature of the soul itself for his readers with the famous flying man image. Imagine a man floating in air or void with no physical contact with anything else and no sensory input of any sort. Such a person, says Avicenna, would undoubtedly hold that he himself exists.
Thus, the self whose existence he asserted is his unique characteristic, in the sense that it is he himself, not his body and its parts, which he did not so assert. Thus, what [the reader] has been alerted to is a way to be made alert to the existence of the soul as something that is not the body-nor in fact any body-to recognize it and be aware of it, if it is in fact the case that he has been disregarding it and needed to be hit over the head with it. (Avicenna 2007, p. 179)
Using the body as a tool or instrument, the human rational soul accrues knowledge through the senses by a process of intellectual abstraction wherein the separate Agent Intellect assists in the reasoning efforts of the individual human being based on sensory experiences. In this way the individual comes to grasp the intelligible in act, that is, the essence or essential (real) definition necessary for scientific knowledge. Precisely how this takes place is a matter of controversy among present-day scholars of Avicenna. Some reason that the Agent Intellect assists in the abstraction by an empowering presence in the rational soul, while others reason that, when the rational soul is suitably prepared, the Agent Intellect emanates from itself an intelligible which is received by the human rational soul. (See Gutas 2001; Hasse 2013; Black 2014; Taylor forthcoming) Regardless of what Avicenna himself held, the Latin tradition generally held the latter view and found for Avicenna that the emanation of forms from the Agent Intellect provides human beings with scientific knowledge and certainty. The knower here is the immaterial human rational soul which lives beyond the death of the body without any literally understood resurrection and reunification with the body. (Marmura 2012)
          Further, Avicenna’s interpretation of Aristotle on the definition of the essence plays a central role here. Does the definition of a thing as an expression of the essence of a thing include only the form or does it include the form and matter of a composite thing? Aristotle took both positions but Avicenna chose to follow the second, that the essence includes both form and matter. In this Aquinas followed Avicenna and was able to use this reasoning to construct his conception of the soul such that the soul is a hoc aliquid (that is, determinate particular entity in its own right, a substance in its own right) which shares its being with the body. This is closely connected to the notion that for Avicenna the essence does not include existence as part of itself but must receive it from something else. Aquinas uses this notion to overcome the problem of the soul as an independent entity — a hoc aliquid — in its own right, and at the same time something that shares its being with the body during the time of mortal material existence in composition with the body.
          What is more, in his Metaphysics, Book 1, chapters 4-7, Avicenna argues that there is only one Necessary Being and that all other things or essences are in themselves only possible beings and so must receive existence from the Necessary Being in order to be made to be necessary in existence. Only one being — the Necessary Being — is such that its quiddity includes its existence, while all other quiddities as possible beings must receive existence from outside themselves. We will see this reasoning used explicitly by Aquinas at the end of his response in article Whether the soul is simple, In 3 Sent. d.5, q.3, a.2, resp.
Readings:
          Selections from Avicenna’s De Anima of the Shifa: Book 1 on the nature of the soul and Book 5 on the practical and theoretical faculties of the soul. These texts are available at at https://marq-my.sharepoint.com/:f:/g/personal/richard_taylor_marquette_edu/ErCuBjo8-s9IiOwnN671tfYBt9-XMk-0OZDQNO8f-oDryg?e=EogTxG
           Avicenna provided Aquinas with important reasoning regarding the nature of the human soul as a immaterial entity that is possible in itself and receptive of being from another. The notion that the essence of the soul does not include existence meant that the rational soul had to be created and given existence from something else. But for Avicenna the human being created in the body is a rational immaterial soul using the body as a tool and after death only this rational immaterial soul lives on.
         It was Ibn Rushd /Averroes who insisted that the human soul is form of the body (following Aristotle) and that at the same time intellect (mind, nous, ‘aql) is another kind of soul (again following Aristotle). For Ibn Rushd /Averroes all human knowledge comes from experience of the content of the world. This means that human senses and individual experience are essential in the formation of knowledge. In a very real sense the naturally existing perishable human being does not have a personal intellect (though it does have a personal cogitative power and a personal memory in the brain). The formation of knowledge which is quite evident in human beings then requires assistance from above in two ways. First, it requires the intellectualizing power of the Agent Intellect to extract or abstract content from images in the cogitative power or memory and to transfer them to a higher level of existence so that they are now intelligibles in act. These immaterial intelligibles in act cannot exist as such in the individual human bodily powers. Hence, there must be a separate receptive intellect into which these abstracted intelligibles now immaterially in act can be stored. This receptive intellect — requires by the reasoning about the nature of intelligibles in act and human knowing — is the separate Material Intellect which is unique in being receptive and also intellect and unique again as the one thesaursus of intelligibles shared by all human beings. Following Themistius Averroes holds that intersubjective discourse and scientific knowledge require common referents, so there must be just one set of abstracted intelligibles in act housed in the Material Intellect.
         In is important to know in this account that for Ibn Rushd /Averroes the content of knowledge does not come from above but from below and this explains the teleological need for the senses. Hence, of there to be knowledge on the part of human beings, the human soul must be embodied. Without embodiment and bodily sensory experiences formed by imagination and cogitation to yield the content of memory, the abstraction, intelligizing and transferring of intelligibles in potency of the sensory world would never bring about immaterial intellectual knowledge.
         As we shall see, the human being has a separate immaterial rational soul of which intellectual understanding gives evidence. This and more is a contribution from Avicenna as well as Augustine and thinkers of the Latin tradition for Aquinas. But it is Avicenna who reasoned philosophically in persuasive ways carefully studied by Aquinas. For Avicenna the relation of soul to body was not a unitary one. For the sake of the unity of human nature and the individual human soul, Aquinas needed to draw on Averroes. Though Aquinas rejected the idea of a separate Material Intellect, Aquinas needed a contribution on the nature of the power that receives abstracted intelligibles from the thought of Averroes in forming his conception the unity of the human person. But I am getting ahead of my story which reveals a key mediating thinker between the Arabic tradition and Aquinas,
Part Four. Let’s start again, now focused on: Aquinas on the nature of the soul
B. Carlos Bazán, “The human soul. form and substance? Thomas Aquinas’ Critique of eclectic Aristotelianism,” AHDLMA 64 1997.
The Problem of the Soul and Body
          In the early 13th century theologians of Latin Christendom struggled to give a coherent account of human nature as composite of body and soul. On the one hand, it was clear that human beings are body and soul. But the soul does not die with the death of the body but rather lives on. But Christian teachings held that the body would be resurrected and united with the soul in the afterlife. Yet if the soul could continue to live after the death of the body but before the general resurrection, it would seem that the soul must be a substance in its own right (a hoc aliquid, a determinate particular entity, a tode ti) and the body another substance. The account of Avicenna was attractive but it allowed no reasoning for supporting the view that the soul and body are an essential unity. One way theologians argued (certainly begging the question their very forming of the principle) was to say that the human soul has unibilitas or ‘unite-ability’ in relation to the body. This period is described by B. Carlos Bazán as a period of eclectic Aristotelianism in his article, “The human soul. form and substance? Thomas Aquinas’ Critique of eclectic Aristotelianism,” AHDLMA 64 1997.) And, according to Bazán the teaching of Aquinas that “The soul is a subsistent substantial form, a form of matter but not a material form, and it must be acknowledged that there is no such form in the ontological scale of entities established by Aristotle” (p. 121) is developed by Aquinas in a novel analysis of his own making. This view has recently been contested by Nathan Blackerby in a 2017 doctoral dissertation entitled, “Contextualizing Aquinas’s Ontology of Soul: An Analysis of his Arabic and Neoplatonic Sources,” Marquette University, Milwaukee, Wisconsin. (See http://epublications.marquette.edu/do/search/?q=Blackerby&start=0&context=1093699&facet=.) Rather, Blackerby argues that the primary source for the principles used by Aquinas are found in Avicenna’s writings on essence.
          What emerges from the reasoning of Aquinas is the notion that the human soul is indeed a hoc aliquid or entity that can subsist on its own but only as forma partis (form of the part) and not as a natural whole. The natural whole of the human person is the unity of body and soul. The soul, however, has powers of intellect that are immaterial and not affected by the death of the body. After death the soul finds itself in a stage of incompleteness as an immaterial subject possessing intellectual powers. Without the body, however, the human soul is not able to exercise bodily powers. Since its nature is such that it is both body and intellect, a human being stands as the highest of bodily creatures and the lowest of intellectual creatures. It uses the body and its senses to come to have intellectual understanding through intellectual abstraction of the forms or species of material beings. In this way, through the abstraction and making of intelligible species a human being develops intellectual understanding and knowledge from bodily sensory experience and discursive reasoning. This happens through the senses and the senses need sensory organs which can exist only in body. The soul, as Aristotle says, is the first actuality of an natural body with organs that function in distinctively different ways.
A video on Aquinas and his sources in Avicenna and Averroes
on the nature of the soul is available at: https://streaming.mu.edu/Watch/Zb2w9C7K
In the following text Aquinas describes the problem.
Aquinas In 3 Sent. d. 5, q.3, a.2, resp.
© Richard C. Taylor 7 October 2017
Aquinas, In 3 Sent. d.5, q.3, a.2, resp. in
Scriptum Super Sententiis,v.3, ed. Moos (Paris 1933), pp. 206-7:
(After death the separated soul is not the human person but a part of the human being existing by itself in separation from the body.)
I respond that it should be said regarding the union of the soul to the body that there was a twofold opinion among the ancients. There was one which holds that the soul is united to the body as a complete being to a complete being (ens completum enti completo), so that it would be in the body as the sailor is in the ship. Hence, as Gregory of Nyssa says, Plato held that the human being is not something constituted from soul and body, but rather the soul is clothed with the body (corpore induta). According to this the whole personality of a human being would consist in the soul, to the extent that the separated soul could truly be called the human being, as Hugo of St. Victor says. According to this opinion what the Master [scil. Lombard] says would be true, that the soul is a person when it is separate .
But this opinion cannot stand, because in this way the body would come to the soul in the way of an accident. Hence, this name human being — the meaning of which is soul and body — would not signify one per se; and so it would not be in the genus of substance.
Aristotle has a different opinion which all the moderns follow, that the soul is united to the body as a form of matter (anima unitur corpori sicut forma materiae). Hence, the soul is part of the human nature, and not some nature in its own right (non natura quaedam per se). And because the notion of a part is contrary to the notion of a person, as was said, for this reason the separated soul cannot be called a person, because, although the separated is not a part in act, nevertheless it has a nature such that it is a part.
In this text Aquinas draws on reasoning from Avicenna to craft his own new approach to solving the issue.
For a video lecture on Aquinas on the soul in the Commentary on the Sentences, see https://streaming.mu.edu/Watch/Zb2w9C7K
© Richard C. Taylor 7 October 2017
Thomas Aquinas, In 1 Sent D. 8, Q. 5, A. 2
Whether the soul is simple
         To the second we proceed as follows.
         1. It seems that the soul is simple. For as the Philosopher says (De anima 2, text 2), the soul is the form of the body. But in the same place he says that form is neither the matter nor the composite. Therefore the soul is not composed.
         2. Furthermore, everything that is composed has being from its its components. If, therefore, the soul is composed, then it has some being in itself and that being is ever removed from it. But from the conjunction of the soul to the body it follows that a certain being which is the being of a human being. Therefore, there is a twofold being in the human being, namely the being of the soul and the being of what is conjoined. [However,] that cannot be the case since the being of one thing has a unique being.
         3. Furthermore, every [sort of] composition that comes to a thing after its complete being is accidental to it. If, therefore, the soul is composed of its principles, having complete being in itself, its composition to the body will be accidental for it. But accidental composition is limited to one thing accidentally. Therefore, only something one accidentally is brought about from soul and body; and so a human being is not a being in its own right (per se), but only accidentally (per accidens).
         4. To the contrary is what is found in Boethius [De Trinitate 1, ch. 2, col. 1250, t. II): No simple form can be a subject. But the soul is a subject for powers, dispositions, and intelligible species (potentiarum et habituum et specierum intelligibilium). Therefore it is not a simple form.
         5. Furthermore, a simple form does not have being per se, as was said. But that which does not have being except insofar as it is in something else cannot remain [in existence] after that [in which it is contained], nor too can it be a mover although it can be a principle of motion, because it is a being complete in itself. Hence, [for example] the form of fire is not a mover, as it is said in Physics 8 [text. 40]. The soul, however, remains after the body and is the mover of the body. Therefore it is not a simple form.
         6. Furthermore, no simple form has in itself what individuates it, since every form is in its own right common. If, therefore, the soul is a simple form, it will not have in itself what individuates it, but it will be individuated only through the body. However, when what is the cause of individuation has been removed, individuation is destroyed. Therefore, when the body has been removed, diverse souls will not remain as individuals. Thus, there will remain only one soul which will be itself the nature of soul.
         Solution.
         I respond that it should be said that here there is a twofold opinion. (1) For some say that the soul is composed of matter and form, and there are some of these who say that the same matter of the soul belongs also to other corporeal and spiritual things. But this does not seem to be true because no form is made intelligible except insofar as it is separated from matter and the concomitants of matter. However, this is not insofar as it is corporeal matter perfected by corporeity, since the form of corporeity is intelligible through separation from matter. Hence, those substances which are intelligible naturally do not seem to be material, otherwise the species of things in themselves would not exist according to intelligible being. Hence, Avicenna [Metaphysics, book 3, ch. 8, Van Riet ed., pp. 158-9.] says that something is said to be intellective because it is free of matter. And furthermore, prime matter, to the extent that it is considered stripped of all form, does not have some diversity, nor [reading nec with Parma, not Mandonnet’s sed] is it made diverse through some accidents before the advent of the substantial form since accidental being does not precede substantial [being]. One perfection [alone] belongs to one perfectible thing. Therefore, it is necessary that the first substantial form perfect the whole matter. But the first form which is received in matter is corporeity, of which the thing is never divested, as the Commentator [Averroes] says [in his Comm. on Physics 1, text & comm. 63]. Therefore the form of corporeity is in the whole matter and so matter will exist only in bodies. For if you were to say that the quiddity of a substance were the first form received in matter, still the same issue will arise. [This is] because matter does not have division from the quiddity of the substance but from corporeity, which the divisions of quantity in act follow. Later diverse forms are acquired in it through the division of matter insofar as it is disposed in diverse places. For the order of the nobility in bodies seems to be according to the order of their place, as fire is above air. For this reason it seems that the soul does not have matter unless matter is taken in an equivocal way.
         (2) Others say that soul is composed of “that by which it is (quo est)” and “what is (quod est)”. However, “what is” differs from matter, because “what is” indicates the supposit itself having being. But matter does not have being but rather the composite of matter and form [has being]; hence, matter is not “what is” but rather the composite [is “what is”]. Hence, in all things in which there is a composition of matter and form there is also a composition of “that by which it is” and “what is.” However, in things composed of matter and form this can be said in three ways. (i) For “that by which it is” can be called the form of the part itself, which gives being to matter. (ii) “That by which it is” can also be calls the very act of existing (ipse actus essendi), namely, being (esse), as that way which one runs is the act of running. (iii) “That by which it is” can also be called the very nature which results from the conjunction of form with matter, such as humanity. This is chiefly for those who assert that the form which is the whole — which is also called the quiddity — is not the form of the part, concerning which Avicenna [writes in Metaphysics 5, ch. 3]. However, since it is of the very notion of the quiddity or essence that it is not what is composed or a composite, what results can be found and understood as some simple quiddity, not something following the composition of form and matter. If, however, we would find some quiddity which is not composed of matter and form, that quiddity or its being either is its very being or not. If that quiddity is its very being, in this way it will be the very essence of God Himself which is his very being and it will be altogether simple. But if it is not being itself, it is necessary that it have being acquired from another, as is the case for each created quiddity. And because this quiddity has been asserted not to subsist in matter, being in something else has not been acquired for it, as is the case for composite quiddities, but rather being in itself has been acquired for itself. And in this way the quiddity will be this “that which is” and its very being will be “that by which it is.” Because everything which does not have something of itself is possible with respect to that, a quiddity of this sort — since it has being from another — will be possible with respect to that being and with respect to this from which it has being, in which there is no potency. It this way potency and act will be found in such a quiddity insofar as the quiddity itself is possible and its being is its act. In this way I understand the composition of potency and act in angels to be of “that by which it is” and “that which is” and likewise in the soul. Hence, the angel or soul can be said to be a quiddity or nature or simple form, insofar as the quiddity of these is not composed of diverse things. But, nevertheless, there a composition of these two, namely, of quiddity and being, comes about.
[Responses to objections]
         1. To the first therefore it should be said that the soul is not composed of things which are parts of its quiddity, as is also the case for any other form. But because the soul is a simple form not dependent on matter — something which belongs to it on account of its likeness and nearness to God — it has being in its own right (per se) which other corporeal forms do not have. Hence, in the soul there is found a composition of “being (esse)” and “what is (quod est)” and not in other forms. [This is] because being itself absolutely does not belong to corporeal forms, as [it belongs] to these things which exist but [are] composite.
         2. To the second it should be said that the soul undoubtedly has complete being in itself, although this being does not result from the parts composing its quiddity, nor is some other being brought about through the conjunction of body. Rather, this being itself which belongs to the soul per se comes to be the being of what is conjoined. For the being of the conjunct is nothing but the being of the form itself. But it is true that some material forms do not subsist through that being on account of their imperfections, but they are only principles of being.
         3. In virtue of this also the solution to the third objection is also evident. [This is] because the composition which comes to the soul after complete being, according to the mode of understanding, does not make another being because undoubtedly that being would be accidental and for this reason it does not follow that the human being is a being accidentally (per accidens).
         4. To the fourth it should be said that, if Boethius speaks concerning subject in relation to any of its accidents, his statement is true concerning the form which simple such that it is also its being, as is God. Such simplicity is neither in the soul nor in an angel. However, if he speaks of the subject in relation to accidents which have being grounded in nature (firmum in natura) and which are accidents of an individual, then his statement is true also concerning a simple form the quiddity of which is not composed of parts. For there are some accidents which do not have being truly but only intentions of natural things. Of this sort are the species of things which are in the soul. Again, among accidents having the being of nature, some follow upon the nature of the individual, namely, matter, through which the nature is divided, as white and black in human beings. Hence, they also do not follow for the whole species, and the soul cannot be the subject for such accidents. However, some have the being of nature but they follow from the principles of the species, as [those that] are properties consequent upon the species. A simple form can be the subject for such accidents. Nevertheless, this [form] is not its own being by reason of the possibility which is in its quiddity, as was said, and such accidents are powers of the soul, for in this fashion both the point and unity have their properties.
         5. To the fifth it should be said that every form is some likeness of the First Principle which is pure act. Hence, to the extent that [a form] approaches more closely to Its likeness, [that form] participates more of Its perfections. However, among forms of bodies (Inter formas autem corporum) the rational soul approaches more closely to the likeness of God. For this reason it participates some of the nobilities of God, namely that it understands (quod intelligit), that it is able to move, that it has being in its own right (quod habet esse per se), the sensible soul less, the vegetable soul still less, and so forth. Therefore I say that neither does to move belong to the soul nor to have absolute being (esse absolutum: simple being) insofar as it is form, but rather insofar as it is a likeness of God.
         6. To the sixth it should be said that, according to the things said earlier, there is not something in the soul by virtue of which it is individuated. They who denied it to be a determinate particular (hoc aliquid) understood this and not that it does not have absolute being (absolutum esse: simple being). I say that it is not individuated except from the body. Hence, the error of those asserting that souls are created beforehand and later placed in bodies (incorporatas: incorporated) is something impossible, because they are not made many except insofar as they are impressed in a plurality of bodies. But, although the individuation of souls depends on body with respect to its beginning, nevertheless [it does] not [depend on the body] with respect to its end, namely, in such a way that when bodies cease to exist, the individuation of souls ceases (reading cessat with Parma). The reason for this is that, since every perfection is impressed on matter according to its capacity, the nature of the soul will be impressed on diverse bodies in this way, not according to the same nobility and purity. Hence, in any given body the being will have a determination according to the measure of the body. However, the determined being, although it is acquired by the soul in the body, nevertheless [it is] not from body nor through dependence on body. Hence, when bodies are removed, there still will remain for each soul its own determinate being, according to the affections or dispositions which followed for it, to the extent that it was the perfection of such a body. This is the solution of Avicenna [De anima 1, ch.3] and can be made evident by a sensible example. For if some one thing does not retain a shape distinguished though diverse vases, as is the case for water, when the vases will be removed, the proper distinctive shapes will not remain, but there will remain just one water. Such is the case concerning material forms which do not retain being in their own right (esse per se). However, if there is something retaining shape which is distinguished according to diverse shapes through diverse instruments, when those have also been removed, the distinction of shapes will remain, as is clear in [the case of] wax. And such is the case concerning the soul which retains its own being after the destruction of the body, because individuated and distinct being also remains in it.
Disputed Question on the Soul. An extract from https://isidore.co/aquinas/QDdeAnima.htm#1
Question 1
WHETHER THE SOUL CAN BE A FORM AND A PARTICULAR THING
In the first article we examine this question: Whether the human soul can be a form and a particular thing.
Objections
It seems that the human soul cannot be a form and a particular thing. For if the human soul is a particular thing, it is a subsisting thing having a complete act of existing (esse) in virtue of its own nature. Now whatever accrues to a thing over and above, its complete [substantial] existence, is an accident of that thing as whiteness and clothing are accidents of man. Therefore, when the body is united to the soul, it is united to it accidentally. Consequently, if the soul is a particular thing, it is not the substantial form of the body.
Further, if the soul is a particular thing, it must be an individuated thing, for a universal is not a particular thing. Now the soul is individuated either by something other than itself, or by itself. If the soul is individuated by something other than itself, and is the form of the body, it must be individuated by the body (for forms are individuated by their proper matter). And thus it follows that when the body is separated from the soul, the latter loses its individuation. In that case the soul could not subsist of itself nor be a particular thing. On the other hand, if the soul is individuated by itself, it is either a form in its entirety (simplex) or is something composed of matter and form. If it is a form in its entirety, it follows that one individuated soul could differ from another only according to form. But difference in form causes difference in species. Hence it would follow that the souls of different men are specifically diverse; and if the soul is the form of the body, men differ specifically among themselves, because each and every thing derives its species from its proper form. On the other hand, if the soul is composed of matter and form, it would be impossible for the soul as a whole to be the form of the body, for the matter of a thing never has the nature of a form. It follows, then, that the soul cannot be at once both a particular thing and a form.
Further, if the soul is a particular thing, it follows that it is an individual. Now every individual belongs to a species and a genus. Consequently the soul will have a proper species and a proper genus. But a thing possessing its own species cannot have anything else super-added to it in order to give it its species, because, as the Philosopher, points out [Metaph., VIII, 3 (1043b 36)], the forms or species of things are like numbers whose species change if a unit is added or subtracted. Matter and form, however, are united in order to constitute a species. Therefore, if the soul is a particular thing, it is not united to the body as a form to matter.
Further, since God made things because of His goodness, which is manifested in the different grades of things, He instituted as many grades of beings as nature could admit. Hence, if the human soul can subsist in itself (which must be maintained if it is a particular thing), it would then constitute a distinct grade of being. But forms without matter do not themselves constitute a distinct grade of being. Thus, if the soul is a particular thing, it will not be the form of any matter.
Further, if the soul is a particular thing, subsisting in itself, it must be incorruptible, for neither has it a contrary, nor is it composed of contraries . But if the soul is incorruptible, it cannot be proportioned to a corruptible body such as the human body is. Now every form is proportioned to its matter. So if the soul is a particular thing, it will not be the form of the human body.
Further, the only subsisting being that is Pure Act, is God. Therefore, if the soul is a particular self-subsisting thing, it will be composed of act and potentiality, and thus will not be a form, because no potentiality is an act. Consequently, if the soul is a particular thing, it will not be a form.
Further, if the soul is a particular thing capable of subsisting in itself, it would need to be united to a body only for a good accruing to the soul, either for an essential good or an accidental one. Not for an essential good, however, because it can subsist without the body. Nor even for an accidental good; for the knowledge of truth which the human soul can acquire through the senses (themselves incapable of existing without bodily organs) is evidently a pre-eminent good of this sort; but some hold that the souls of still-born infants have a perfect knowledge of things, and these certainly never acquired that knowledge through their senses. Consequently, if the soul is a particular thing, there is no reason why it should be united as a form to the body.
Further, a form and a particular thing are distinguished from each other as opposites; for the Philosopher says in the De anima [III, 2 (414a 15)], that substance has a threefold division: the first is form, the second, matter, and the third, this particular thing. But opposites are not predicated of one and the same thing. Therefore the human soul cannot be a form and a particular thing.
Further, it belongs to the very essence of a particular thing to subsist of itself. But it is proper to a form to exist in something else. These seem to be contradictory. Consequently, if the soul is a particular thing, it is apparently not a form.
But it might be said that when the body corrupts, the soul still remains a particular self-subsisting thing, but then loses the nature of a form. On the other hand, whatever can exist apart from a thing and retain the nature of a substance, exists in that thing accidentally. Therefore, if the soul continues to exist after the body corrupts, the soul ceases to have the character of a form; and thus the nature of a form belongs to it only accidentally. But it is only as a form that the soul is united to the body in order to constitute a man. Hence the soul is united to the body accidentally, and thus man will be a being per accidens. This is incongruous.
Further, if the human soul is a particular self-subsisting thing, it must have an operation of its own, because a thing that exists of itself has its own proper operation. But the human soul does not have its own proper operation, because the act of intellection itself, which seems to be proper above all to the soul, is not an activity of the soul, but that of a man through his soul, as is stated in the De anima [I, 4 (408a 14)]. Therefore the human soul is not a particular thing.
Further, if the human soul is the form of the body, it must depend in some way on the body, for form and matter depend on each other. But whatever depends on something else [in this way] is not a particular thing. Therefore, if the soul is the form of the body, it will not be a particular thing.
Further, if the soul is the form of the body, there must be one act of existing (esse) common to the soul and the body; because from the union of matter and form there results a thing having one act of existing. But there cannot be one act of existing common to the soul and the body, since they are generically diverse; for the soul belongs to the genus of incorporeal substance, and the body to that of corporeal substance. Hence the soul cannot be the form of the body.
Further, the body’s act of existing is a corruptible one resulting from quantitative parts. The soul’s act of existing, on the other hand, is incorruptible and simple. Therefore there is not one act of existing possessed in common by the body and the soul.
But it might be said that the human body itself has the act of existing of a body through the soul. On the contrary, the Philosopher says [Ibid., II, 1 (412b 5)] that the soul is the act of a physical organic body. Therefore that entity which is related to the soul as matter to act, is now a physical organic body; and this body can exist only through a form whereby it is placed in the genus of body. Consequently the human body possesses its own act of existing distinct from that of the soul.
Further, the essential principles of matter and form are ordered to the act of existing (esse). But whatever can be brought about in nature by one principle, does not require two. Therefore, if the soul has in itself its own act of existing because it is a particular thing, then the body by nature is united to the soul only as a matter to a form.
Further, the act of existing is related to the substance of the soul as its act. Hence the act of existing must be supreme in the soul. But an inferior being is not related to a superior one with respect to that which is supreme in the superior, but rather with respect to that which is lowest in it. For Dionysius says [De divinis nominibus, VII, 2] that divine wisdom joins that which is highest (fines) in primary things [i.e., those having less perfection] to that which is lowest (principiis) in secondary ones [i.e., those having greater perfection]. Therefore the body, which is inferior to the soul, does not attain to that act of existing which is supreme in the soul.
Further, things having one and the same act of existing, have one and the same operation. Therefore, if the act of existing of the human soul, when joined to the body, belongs also to the body, the act of understanding, which is the operation of the soul, will belong both to the soul and the body. This is impossible, as is proved in the De anima [, 4 (429a 18)]. Consequently there is not one act of existing for both the human soul and the body. Hence it follows that the soul is not the form of the body and a particular thing.
On the contrary, a thing receives its species through its proper form. But man is man because he is rational. Hence the rational soul is the proper form of man. Moreover the soul is a particular self-subsisting thing because it operates of itself; for its act of understanding is not performed through a bodily organ, as is proved in the De anima [III, 4 (429a 24)]. Consequently the human soul is a particular thing and a form.
Further, the highest perfection of the human soul consists in knowledge of truth which is acquired through the intellect. Moreover the soul must be united to the body in order to be ‘perfected in knowledge of truth, because it understands through phantasms which are non-existent without the body. Consequently the soul must be united as a form to the body and must be a particular thing as well.
I answer: “A particular thing (hoc aliquid),” properly speaking, designates an individual in the genus of substance. For the Philosopher says, in the Categories [V, 2a 10], that first substances undoubtedly signify particular things; second substances, indeed, although they seem to signify particular things, rather signify the specific essence (quale quid). Furthermore, an individual in the genus of substance is capable not only of subsisting of itself, but is also a complete entity belonging to a definite species and genus of substance. Wherefore the Philosopher, in the Categories [V, 3a 28], also calls a hand and a foot, and things of this sort, parts of substances rather than first or second substances. For although they do not exist in another as a subject (which is characteristic of a substance), they still do not possess completely the nature of a species. Hence they belong to a species or to a genus only by reduction.
Now some men have denied that the human soul possesses these two real characteristics belonging to a particular thing by its very nature, because they said that the soul is a harmony, as Empedocles did, or a combination [of the elements], as Galen did, or something of this kind. For then the soul will neither be able to subsist of itself, nor will it be a complete thing belonging to a species or genus of substance, but will be a form similar only to other material forms.
But this position is untenable as regards the vegetal soul, whose operations necessarily require some principle surpassing the active and passive qualities [of the elements] which play only an instrumental role in nutrition and growth, as is proved in the De anima [II, 4. 415b 28]. Moreover, a combination and a harmony do not transcend the elemental qualities. This position is likewise untenable as regards the sentient soul, whose operations consist in receiving species separated from matter, as is shown in the De anima [II, 12, 424a 16]. For inasmuch as active and passive qualities are dispositions of matter, they do not transcend matter. Again, this position is even less tenable as regards the rational soul, whose operation consists in understanding, and in abstracting species not only from matter, but from all individuating conditions, this being required for the understanding of universals. However, in the case of the rational soul something of special importance must still be considered, because not only does it receive intelligible species without matter and material conditions, but it is also quite impossible for it, in performing its proper operation, to have anything in common with a bodily organ, as though something corporeal might be an organ of understanding, just as the eye is the organ of sight, as is proved in the De anima [III, 4, 429a 24]. Thus the intellective soul, inasmuch as it performs its proper operation without communicating in any way with the body, must act of itself. And because a thing acts so far as it is actual, the intellective soul must have a complete act of existing in itself, depending in no way on the body. For forms whose act of existing depends on matter or on a subject do not operate of themselves. Heat, for instance, does not act, but something hot.
For this reason the later Greek philosophers came to the conclusion that the intellective part of the soul is a self-subsisting thing. For the Philosopher says, in the De anima [III, 5, 430a 24], that the intellect is a substance, and is not corrupted. The teaching of Plato [Phaedrus, 24] who maintains that the soul is incorruptible and subsists of itself in view of the fact that it moves itself, amounts to the same thing. For he took “motion” in a broad sense to signify every operation; hence he understands that the soul moves itself because it moves itself by itself.
But elsewhere [Alcibiades, 25-26] Plato maintained that the human soul not only subsisted of itself, but also had the complete nature of a species. For he held that the complete nature of the [human] species is found in the soul, saying that a man is not a composite of soul and body, but a soul joined to a body in such a way that it is related to the body as a pilot is to a ship, or as one clothed to his clothing. However, this position is untenable, because it is obvious that the soul is the reality which gives life to the body. Moreover, vital activity (vivere) is the act of existing (esse) of living things. Consequently the soul is that, which gives the human body its act of existing. Now a form is of this nature. Therefore the human soul is the form of the body. But if the soul were, in the body as a pilot is in, a ship, it would give neither the body nor its parts their specific nature. The contrary of this is seen to be true, because, when the soul leaves the body, the body’s individual parts retain their original names only in an equivocal sense. For the eye of a dead man, like the eye of a portrait or that of a statue, is called an eye equivocally; and similarly for the other parts of the body. Furthermore, if the soul were in the body as a pilot in a ship, it would follow that the union of soul and body would be an accidental one. Then death, which brings about their separation, would not be a substantial corruption; which is clearly false. So it follows that the soul is a particular thing and that it can subsist of itself, not as a thing having a complete species of its own, but as completing the human species by being the form of the body. Hence it likewise follows that it is both a form and a particular thing.
Indeed, this can be shown from the order of natural forms. For we find among the forms of lower bodies that the higher a form is, the more it resembles and approaches higher principles. This can be seen from the proper operation of forms. For the forms of the elements, being lowest [in the order of forms] and nearest to matter, possess no operation surpassing their active and passive qualities, such as rarefaction and condensation, and the like, which appear to be material dispositions. Over and above these forms are those of the mixed bodies and these forms have (in addition to the above mentioned operations) a certain activity, consequent upon their species, which they receive from the celestial bodies. The magnet, for instance, attracts iron not because of its heat or its cold or anything of this sort, but because it shares in the powers of the heavens. Again, surpassing these forms are the souls of plants, which resemble not only the forms of earthly bodies but also the movers of the celestial bodies inasmuch as they are principles of a certain motion, themselves being moved. Still higher are brute beasts’ forms, which now resemble a substance moving a celestial body not only because of the operation whereby they move bodies but also because they are capable of knowledge, although their knowledge is concerned merely with material things and belongs to the material order (for which reason they require bodily organs). Again, over and above these forms, and in the highest place, are human souls, which certainly resemble superior substances with respect to the kind of knowledge they possess, because they are capable of knowing immaterial things by their act of intellection. However, human souls differ from superior substances inasmuch as the human soul’s intellective power, by its very nature, must acquire its immaterial knowledge from the knowledge of material things attained through the senses.
Consequently the human soul’s mode of existing can be known from its operation. For, inasmuch as the human soul has an operation transcending the material order, its act of existing transcends the body and does not depend on the body. Indeed, inasmuch as the soul is naturally capable of acquiring immaterial knowledge from material things, evidently its species can be complete only when it is united to a body. For a thing’s species is complete only if it has the things necessary for the proper operation of its species. Consequently, if the human soul, inasmuch as it is united as a form to the body, has an act of existing which transcends the body and does not depend on it, obviously the soul itself is established on the boundary line dividing corporeal from separate substances.
Answers to objections
Although the soul has a complete act of existing of its own, it does not follow that the body is united to it accidentally: first, because the same act of existing that belongs to the soul is conferred on the body by the soul so that there is one act of existing for the whole composite; secondly, because, while the soul can subsist of itself, it does not have a complete species, for the soul needs the body in order to complete its species.
The act of existing (esse) and individuation (individuatio) of a thing are always found together. For universals do not exist in reality inasmuch as they are universals, but only inasmuch as they are individuated. Therefore, although the soul receives its act of existing from God as from an active principle, and exists in the body as in matter, nevertheless the soul’s act, of existing does not cease when the body corrupts, nor does the soul’s individuation cease when the body corrupts, even though it has a relationship to the body.
The human soul is not a particular thing as though it were a substance having a complete species in itself, but inasmuch as it is part of a thing having a complete species, as is clear from what has been said. Therefore the conclusion in the objection is false.
Although the human soul subsists of itself, it does not have a complete species in virtue of its very nature. Consequently souls existing apart from bodies cannot constitute a distinct grade of being.
The human body is the matter proportioned to the human soul, for the body is related to the soul as potentiality is to act. However, as regards its capacity for existing the soul need not be on a par with the body, because the human soul is not a form totally embraced by matter. This is evident from the fact that one of the soul’s operations transcends matter. However, another explanation can be given in accordance with the position of faith, namely, that in the beginning the human body was in some way created incorruptible and incurred the necessity of dying through sin, from which necessity it will be freed once again at the resurrection. Hence it is accidental that the body does not share in the incorruptibility of the soul.
Since the human soul is a subsisting being, it is composed of potentiality and act. For the substance itself of the soul is not its own act of existing, but is related to its act of existing as potentiality is to act. However, it does not follow that the soul cannot be the form of the body, because, even in the case of other forms, whatever is like form and act in relation to one thing is like potentiality in relation to something else; just as transparency is formally present to the atmosphere, which is in potency in relation to light.
The soul is united to the body both for a good which is a substantial perfection, namely, the completion of the human species; and for a good which is an accidental perfection, namely, the perfecting of the soul in intellectual knowledge which it acquires from the senses; for this mode of understanding is natural to man. Nor is this position rendered untenable if the separated souls of infants and those of other men employ a different mode of understanding, for these souls are capable of such intellection rather by reason of being separated from the body than by reason of their human species.
It is not of the very nature of a particular thing to be composed of matter and form, but only to be capable of subsisting in itself. Consequently, although a composite [of matter and form] is a particular thing, this does not prevent other beings [i.e., those not composed of matter and form] from being particular things.
For a thing to exist in another as an accident in a subject, prevents that thing from having the nature of a particular thing. However, for a thing to exist in another as part of it (and the soul exists in man in this way) does not altogether prevent a thing having such an existence from being called a particular thing.
When the body is corrupted the soul does not lose the nature which belongs to it as a form, despite the fact that it does not actually perfect matter as a form.
Intellection is the operation proper to the soul, if the soul is considered to be the principle from which the operation flows, for this operation is not exercised by the soul through some bodily organ as sight is exercised through the eye. Nevertheless the body shares in this operation on the side of the object, for phantasms, which are the objects of the intellect, cannot exist without bodily organs.
Although the soul has some dependence on the body inasmuch as the soul’s species is not complete without the body, the soul does not depend on the body in such a way that it cannot exist without the body.
If the soul is the form of the body, the soul and the body must have one common act of existing which is the act of existing of the composite. Nor is this prevented by the fact that the soul and the body belong to two different genera, for the soul and the body belong to the same species or genus only by reduction, just as the parts of a whole are reduced, to the species or genus of the whole.
The thing that is properly corrupted is neither the form nor the matter nor the act of existing itself but the composite. Moreover, the body’s act of existing is said to be corruptible inasmuch as the body by corrupting is deprived of the act of existing which it possessed in common with the soul; which act of existing remains in the subsisting soul. The same thing is to be said also for the parts composing the body, because the body is constituted of its parts in such a way that it can receive its act of existing from the soul.
Sometimes in the definitions of forms a subject is considered independently of its form (informe), as when it is said that motion is the act of a being in potentiality. Sometimes, however, the subject is regarded as informed (formatum) as when it is said that motion is the act of a mobile thing, just as light is the act of that which is transparent. Now it is in this way that the soul is said to be the act of a physical organic body, because the soul causes it to be a physical organic body just as light makes something to be lucid.
The essential principles of a species are not related merely to an act of existing, but to the act of existing of this [particular] species. Consequently, although the soul can exist of itself, it cannot be complete in its species without the body.
While the act of existing is the most formal of all principles, it is also the most communicable, although it is not shared in the same measure both by inferior beings and by superior ones. Hence the body shares in the soul’s act of existing, but not as perfectly as the soul does.
Although the soul’s act of existing belongs in a certain measure to the body, the body does not succeed in sharing in the souls’s act of existing to the full extent of its perfection and actuality; and therefore the soul has an operation in which the body does not share.
For his mature teaching on this, see Summa theologiae, prima pars, Q.75, a.4; Q.76, a.1.
Text: https://isidore.co/aquinas/summa/FP/FP075.html#FPQ75OUTP1.
Video lecture: https://streaming.mu.edu/Watch/Fc8g2ESk
Supplementary Translations:
Aquinas In 2 Sent. d. 3, q.1, a.6, resp.
Whether the angel and the [human] soul differ in species.
See http://academic.mu.edu/taylorr/Aquinas_Fall_2012_MU_KUL_UP/Supplementary_Translations__Aquinas_In_2_Sent._D._3,_q.1._A.6.html.