The Human Soul As Form: The Relationship between Aristotle and Catholic Teaching

William Charlton FAITH Magazine May-June 2006

In 1312 the Council of Vienne declared: ‘Anyone who denies that the rational or intellectual soul is essentially and of itself the form of the human body is to be deemed a heretic.’[1] To modern ears, this is a surprising declaration. By “John Brown’s body” we normally mean either his torso, as distinct from his head, arms and legs, or his corpse; and the word “soul” is used only in old-fashioned idioms – “He’s a kindred soul,” “When I got there I found I didn’t know a soul.” The word in the New Testament we translate “soul” is used to mean life, mind, or a complete person. If we use “body” and “soul” in these senses we do not agonise over how they are related; and what would it mean to say that the soul is the form of the body?
Form and Matter

The word “form” (Latin forma or species) is taken here from Aristotle. Aristotle gives the Greek words we translate “form” and “matter” (eidos or morphe and hule) technical senses which he explains by means of examples drawn from human artifacts: a brazen statue or sphere, a house, a bed.[2] A brazen sphere is a sphere made from bronze. In the phrase “a sphere composed of bronze” “sphere” signifies the form the bronze has taken, “bronze” signifies the matter that has taken this form, and “Brazen sphere” signifies the two together. That “brazen sphere” signifies two things is obvious, because there are two words, but sometimes a single word signifies two things together. The word “house” signifies astructure of rigid materials like bricks, stones and logs, while “tent” signifies a structure of cloth or skins. These examples and others given elsewhere[3] show that the relationship of matter and form generally is that of constituents to thing constituted or of that out of which something is made to that which is made out of this. A lintel and a threshold consist of pieces of wood or stone in a certain arrangement; a toddy (melikraton) consists of wine, water and honey mixed in a certain ratio.

Although Aristotle uses the expressions “form”, “matter” and “composite” (sonolon) or “the two together” (to ek touton) he is careful to say that a composite whole does not consist of form and matter. “The syllable does not consist of letters and arrangement, or the house of bricks and arrangement”.[4] At most, form and matter both enter into the meaning of a word for the two together; phrases signifying form and matter are parts of the account of a house; but the only parts or constituents of the house itself are material constituents.
Soul: The Form of a Living Thing

Having introduced the notions of matter and form with examples from artifacts, Aristotle says that words for living organisms and their parts, words, like “man”, “ox”, “garlic”, “eye”, “flesh”, “root” all signify matter and form together, something definite composed or consisting of something definite.[5] He takes “soul”, psuche, to signify whatever it may be that distinguishes a living thing from something non-living or inanimate (our word “inanimate” in fact means “soul-less”) and enables it to see and hear, to move or stay motionless on purpose, even to perform such biological functions as digestion and reproduction.[6]And he says that the soul of a living thing is nothing other thanits form. He takes vegetables to have souls of a kind, though not of a kind that could exist without a body, and in this he is followed by medieval thinkers like Aquinas, but for the present we may ignore the vegetable soul.

Animals consist of limbs and tissues that are put together in a certain way, and the same goes for the limbs and tissues themselves; they – we should say their cells – have varying compositions. Human beings are structures of certain parts, head, eyes, legs but not fins or tails, and their parts are compositions of chemical substances. Furthermore, our vital functions depend on our being such structures; we cannot walk if our legs are broken or see if our retinas get detached, or continue to live at all if the balance of chemicals in our bodies is badly disturbed. So when Aristotle says that the human soul is the form of a human being, does he mean – not, indeed, that it is simply what a non-philosopher would call ‘the human form’, the shape that enables us to recognise a figure seen inthe distance as a human being, but – that it is the structure which the parts or components of  a human being make up?

He does not. The relationship of constituents to things constituted which the examples of the sphere and the statue illustrate gives us only part of the matter-form story. When Aristotle uses a house as an example, he does not say that the form of a house is the structure the materials make up; he says that a house is a shelter for people and their possessions, made up of bricks, beams and the rest put together in a certain way. If he was defining an axe[7] he would say not that it is an arrangement of handle and blade, but that it is a cutting instrument consisting of a blade fitted to a handle. In these definitions, the words which express the form express the function. When Aristotle turns to living organisms, the words he uses to expressthe form are words that signify vital functions: words like “perceive”, “reach for”, “think”. The Greek word anthropos which we must now translate “human being”, not “man”, signifies a conscious purposive agent, consisting of head, torso and limbs put together in a certain way; “conscious purposive agent” expresses the form of a human being, and “head, torso and limbs put together in a certain way” or “chemicals combined in a certain way” expresses the matter. If we are to think of the soul as the form of a human being and the body as the matter, chemical and physical structure belong to the body, not the soul. What philosophers (as distinct from dress-designers and undertakers) mean by “Joanna Brown’s body” is precisely the mixture of chemicals and arrangement of limbs thatconstitutes the purposive agent Joanna.
 Soul and Vital Capacities

All readers agree that Aristotle thinks the soul must be described or conceived in terms of vital functions like perception and purposive movement. But some think that he means that the soul is the capacity for these things, while other think he means that the soul is that which has these capacities.[8] The importance of this issue lies in this. If the soul is that which is capable of perceiving, acting on purpose and the rest, then it is open to us to say that the soul is not something constituted by the body, but rather an incorporeal agent dwelling in it. Shakespeare says in Sonnet 146:

Poor soul, the centre of this sinful earth,
Fooled by these rebel powers that thee array,
Why does thou pine within and suffer dearth
Painting thy outward walls so costly gay?
On the other hand if the soul is the capacities themselves, then it is open to us to say that it is the physico-chemical structure of the body after all, since that structure is precisely what enables human beings to act as they do. I shall argue that both these lines of thought are mistaken and take the second first.

It is hardly controversial that we cannot act, speak or perceive without a certain physical structure; the whole institution of medicine depends on that assumption. But to say that the soul simply is that structure is to claim that all human actions, words and even feelings are the inevitable effect of action upon something with this structure by things around it. Philosophers today who profess to be physicalists make this claim;[9]what it amounts to is explained neatly by Plato. A lyre can give out charming melodies, and what enables it to do this is the length and thickness of the strings and the way they are tuned – a Greek lyre could be tuned to different modes, suitable to different melodies. The tuning, however is a physicalstate which makes it inevitable that when the musician strikes them, a melody is produced. To say that the soul is the physical structure which enables us to speak and act intelligently is to say that our apparently intelligent purposive behaviour is the inevitable result of physical stimulation of our nervous system in the way the lyre’s music is the inevitable result of striking its well-tuned strings. Plato rejects this physicalist view of the soul, and so, quite explicitly, does Aristotle.[10]Aristotle’s objection to it reveals a further element in his conception of form.
Introducing Teleology

One of Aristotle's purposes in distinguishing between matter and form is to distinguish the two kinds of explanation which today we call ‘causal’ and ‘teleological’.  What differentiates a living thing from something inanimate is the fact that its form as well as its matter is a source of change, that is, some of its behaviour is teleologically and not just causally explainable.

The behaviour of non-living things is explained by their matter and, in some cases, also by physical action upon them. For something to be composed of earth, he believed, is for it to have a tendency to move downwards independently of being acted upon; this is like our belief that for objects to have gravitational mass is for them to tend to approach one another independently of any action upon them. And Aristotle thought, as we do, that action such as pushing, pulling and heating affects objects differently depending on the material they contain or arise out of. Explanation of this kind, in terms of forces like gravity and magnetism, and action like pushing and heating and causal action, we call causal; and Aristotle thinks that insofar as something’s behaviour can be explained in thisway, it is due to the thing’s matter. But some of the behaviour of living things – and this is what makes them alive – is explained quite differently. We say that people act or refrain from acting for reasons and purposes. Othello killed Desdemona for the reason that she was unfaithful; Macbeth killed Duncan for the purpose of becoming king. These explanations we call ‘teleological’. Aristotle holds that insofar as a living thing’s behaviour can be explained teleogically it is due to the thing’s form. An artifact like a lyre or an axe has a form; it has a shape and its parts stand in certain relations; but its form is not the source of any of its behaviour. A lyre does not sound, nor does an axe cut, for a reason or purpose; they sound or cut because they are acted upon by the musician orthe forester. The musician, in contrast, acts on the lyre intentionally, as does the forester with his axe on the tree; their action is skilful and due to what Aristotle understands by their form.

The first explanation of the doctrine that body and soul are related as matter and form was that a human being is something constituted by something, and our idea of the human soul is our idea of what is constituted, while our idea of the body is our idea of what constitutes this. We then saw that a description of an object in terms of its function describes its form, whereas a description of it in terms of its physical structure describes rather its matter. We can now add that a thing’s matter is that in it which is responsible for its causally explainable behaviour, while its form is that in it which is responsible for any of its behaviour that can be explained teleologically. If body and soul are the matter and form of a human being, when I think of John Brown as having a certaingravitational mass, and liable to be divided by a blade or blackened by heat, I am thinking of his body; when I think of him as marching in order to liberate slaves I am thinking of his soul.

Aristotle thought that the matter of an object accounts for some of its behaviour independently of action upon it – the behaviour we attribute to fundamental forces. When I move to avoid harm to myself or to prevent harm to a friend, I move for a reason, that is, because (as I know or think) some special circumstance makes the movement necessary or right. Is any of an organism’s behaviour teleologically explainable independently of reasons? Aristotle thought that the processes of growth and digestion are like this; they occur for the good of the organism, but not because of any special circumstance, real or supposed. It is always good for a human being to have hands. That was where the vegetable soul came in. If plants are alive, some of their behaviour must be teleologically explainable,and this will be assimilation of nourishment and growth. Scientists today are inclined to think that these biological processes are causally explainable: now that we have cracked the genetic code we can see see how it is inevitable that we should have the bodily parts and stature we need to act as we do. If this is true then we may have to jettison the vegetable soul; but I do not think that if our having eyes, brains and hands can be explained causally, it follows that none of the use we make of our bodily parts is rational or purposive.

I say we may have to discard the vegetable soul. But does it in fact follow, if something can be explained causally, that it cannot be explained teleologically? When I write a letter, say, impulses pass down my nerves from my brain and cause my muscles and tendons to move or change. Can my writing be truly purposive if these processes are the inevitable effect, given the structure of my brain, of action by sounds, light and heat on my sensory system? If not, then either purposive action is an illusion and in Aristotle’s terms, our soul is not the source of any of our words or deeds; or else it seems there must be a break between the causal chain of events leading to our having the structure we have and having our sensory system stimulated as it is, and the causal chain ofprocesses in the body leading to the effects we bring about by purposive action.
These are deep waters. Most non-philosophers think that causal determination is incompatible with acting of one’s own free will, but I have never seen a watertight argument to prove this incompatibility. And even if the bodily processes which take place as we act intentionally are not determined by a chain of causes stretching back indefinitely, I am not sure that there has to be a sharp break, a real discontinuity, in the causal chain. I discuss these matters elsewhere,[11] but all that needs to be said here is that considering the soul as the form of the body in Aristotle’s way does commit us to holding that some of our behaviour is teleologically explainable.

So much on whether Aristotle thought that our rational or intellectual capacities can be identified with our physical makeup. But given that he did not, did he nevertheless think that the rational soul just is these capacities, or that it is something that possesses them? Some scholars take the former view; and they infer that the soul cannot exist apart from the body, since capacities cannot exist apart from what has them. Aristotle, however, calls these capacities “capacities of soul”, and is unwilling to rule out the existence of the thinking soul without a body.[12] If the soul, however, is a thing with capacities, how can it stand to the body as form to matter, and if it can exist apart from the body, how can it and the bodyform a unity? Instead of being something constituted by bodily parts put together in a certain way it will at best be a non-material thing residing in these bodily parts.

Aristotle sometimes uses common nouns like “sphere” and “shelter” for forms, sometimes abstract expressions like “sphericality”, “shape”, “sight” and “being an axe”. The expressions he uses for the soul, or for what he calls “parts” of the soul, such as to aisthetikon, to orektikon,which scholars often translate “ability to perceive”, “ability to reach out for things” and so on, could equally be translated ‘that which perceives”, “things which reaches out”. If, however, the basic relation of matter to form is that of constituents to what they constitute, the concrete expressions are more natural. Bronze does not constitute sphericality but rather a sphere, or at best an instance of sphericality, since instances of a shape or colour are shaped or coloured objects. Ourbodily parts constitute a thing that sees, hears, thinks and the rest. The capacities to perceive, think and act purposively are capacities of the soul, for Aristotle, because they are capacities of a human being considered as a purposive agent, capacities precisely for behaviour that is teleologically explainable.

Soul as separable from the body?

Philosophers today mostly hold that if the soul is the form of the body it cannot possibly exist without a body.[13] Aquinas was fully aware of the difficulty, but approaches it from a different direction. Before discussing human beings he argues that there are a great many intelligent beings that are completely bodiless, the angels that were accepted by Jews and also some non-Christian Greeks in the first centuries of the Christian era. Hence while modern philosophers ask whether the form of a material object can exist without matter, Aquinas asks whether something that can exist without matter can be the form of a material thing. His argument that it can is rather elaborate,[14] but I thinkit is faithful to Aristotle’s conception of form and matter, and the main point  can be put quite simply. The question whether the concept of an intelligent thinker can serve as a form-concept for a human being is quite independent of the question whether a thinker can exist without a body. If we conceive a human being as something that thinks consisting of head, eyes, hands, feet and the rest, if this is at least part of a correct account of what a human being is, it follows at once that the concept of a thinker is a form-concept. Bernard Williams said if anything is at any time constituted by materials by flesh, bone and nervous tissue it must be essential for it to be so constituted, and it must therefore be impossible for it to exist without a body; but he did not claim to have acast-iron argument for this, only a strong intuition.[15]I see nothing to stop us from saying that a human being is primarily an intelligent agent constituted by bodily parts, but such an agent could cease to be constituted by anything material and exist without a body.

The Source of the Soul

The Catechism of the Catholic Church, s. 366, tells us that “The Catholic Church teaches that every spiritual soul [it means, I think, every human or intellectual as distinct from merely sentient or animal soul] is created directly by God – it is not ‘produced’ by the parents – and also that it is immortal.” Catholic writers today sometimes talk about “ensoulment”, meaning I think, the inserting of a freshly created soul into an embryo. Is this consistent with the view of the soul endorsed by the Council of Vienne?

What, if soul and body are related as form and matter, can “God creates the soul” mean? Aristotle says that a craftsman does not, strictly speaking, make a sphere; he makes a brazen sphere, or causes some bronze to become spherical.[16] Does God cause gametes at conception to become capable of perceiving, thinking and acting intentionally? Aristotle had in mind giving something a form or structure by causal action; only causal powers and properties like shape which belong to the body can be given in this way.

Aristotle tackles the question of how embryos acquire powers of soul in On the Generation of Animals, Book 2, Chapters 1-3. Unlike modern embryologists he takes the material out of which the embryo arises to be supplied solely by the female; the only job of sperm, in species where the male emits sperm, is to be an instrumental cause, it is that by acting with which upon this material the male makes it into a living embryo. Aristotle seems to think it gives it the structure necessary for developing the parts of an organism of the parents’ species; the embryo then develops those parts through its vegetable soul (735a13-14). But while Aristotle also mentions the powers to perceive and think, readers find his account of how these are acquired unclear, and the text has beendoubted especially at the point (736b15-29) where he says that the power to think is the only one which might come in “from outside” – outside the female, and also, apparently, outside the male sperm. There is no agreed interpretation of these lines which gives Aristotle a doctrine consistent with what he says elsewhere.[17] Aristotle thinks that if the exercise of a power requires a special physical structure it cannot exist without that. The power to perceive cannot be exercised by something which is not sensitive to light, sound or tactile properties like heat, and therefore the embryo does not have this power, and is not, by Aristotle’s criteria, an animal, until it has developed a sensory system (736a35-b1). The power to think, whichenables us to make intelligent use of whatever parts we have, does not require any particular physical structure (736b29). Consequently while the power to perceive could, up to a point, be given to the embryo either by its parents at conception or by itself when it takes in nourishment from the mother, the power to think calls for a different explanation. And elsewhere Aristotle can supply one. What enables us, not just to bring things about, but to do so on purpose? Skill. What disposes us to act for particular reasons and purposes? Our character. Aristotle says that we acquire skills, traits of character and also concepts of various sorts of thing gradually by our own efforts as we grow up; whether or not this is getting them “from outside” it is how we should expect him to say that asentient being becomes intelligent. Scientists today say that we cannot act intelligently without having neural structures or patterns of electrical activity in the brain which are not inherited but acquired as we develop perceptual and muscular skills. Implanting the power to think in an embryo independently of the development of its brain sounds like the Pythagorean practice Aristotle deplores of “fitting a soul into a body without specifying what kind of body.”[18]

The Immortality of the Soul

As for immortality, it is one thing to reject an argument that it is impossible to exist without a body, another to supply an argument that it is possible. Nobody makes use of the idea that the soul is the form of the body to argue that it can exist apart. In two lines of his treatise On the Soul Aristotle seems to imply that that in us which thinks is separable from the body, immortal and eternal (430a23-4) but again the text has been doubted and scholars do not agree on any interpretation which gives him a doctrine compatible with the soul’s being the form of the body. John Philoponus in the sixth century said that when he comes to thought, Aristotle simply drops the theory that the soul is related to body as form to matter, and substitutes the theory that it is related as apilot to a ship; a similar view is taken by some modern scholars.[19] As I said just now, there is no particular kind of body we need to use what parts we have intelligently; but it does not follow that we can use them intelligently without a body at all.

The Fourth Lateran Council declared in 1215 that God “at the beginning of time created simultaneously out of nothing spiritual and bodily creatures, angels, that is, and things of this world; and thence human creatures, as something common [sc. to both orders of creation], consisting of spirit and body.”[20] This fits current teaching on the soul’s creation and immortality, but as I said at the beginning, Aristotle denies that matter and form are constituents of a human being, and Council Fathers seem to be working with a theory of the soul more like Plato’s[21]. Plato suggests that the human soul stands to the human body somewhat as a weaver stands to his coat. As the weaver weaves a newcoat for himself or repairs an old one, so I feed my body and stitch up its wounds. The difference is that whereas a weaver is himself a material object, and destined like his coat to yield eventually to the action of physical forces, if we analyse what is involved in intellectual thinking – in measuring, comparing, evaluating, and so forth – we discover, says Plato, that whatever it is in us that thinks intellectually is completely non-material and therefore indestructible. A human being therefore consists of a spiritual soul and a material body somewhat as a fully clothed weaver consists of a living man and inanimate clothes. Plato’s souls are created by a divine Craftsman before the beginning of time,[22] are embodied at conception, andcontinue to exist after being disembodied at death. They are then judged; if they have lived holy lives they are sent to the Isles of the Blessed, if they are curably wicked they are punished in “the Prisonhouse” and if they are incurable they undergo “the greatest, most agonising and most terrifying sufferings for ever as a warning to others.”[23] If we replace disembodied existence before conception by creation at conception this gives the Church the teaching it wants.

Concluding thoughts

It is not surprising if the Fourth Lateran Council uses a Platonic conception of the soul, and the Council of Vienne an Aristotelian. Between the two, the works of Aristotle were translated into Latin and commented upon by such distinguished theologians as Aquinas; and both conceptions are appealing. But they are different, and have different strengths and weaknesses. Plato’s arguments for the immortality of the soul, based as they are on the nature of thinking, show (if successful) that anything which thinks must be immortal; life for human beings after death is as much part of the natural order as breathing before it. But it seems to make us imprisoned souls (or ghosts in machines, as Gilbert Ryle unkindly said) and no philosopher has yet explained how a spiritual soul and a physicalbody might interact. The Aristotelian conception gives a unified picture of human beings as sentient, intelligent agents, and excludes a purely mechanistic account of them; but no philosopher has yet explained how an Aristotelian soul could be “specially created” or exist without a body. Should theologians say they are in the same position as physicists, who use a particle theory for some purposes and a wave theory for others? Or, if that seems irresponsible (as it really is), should they base their theology of life after death not on arguments from the nature of thought but on sayings of Christ like Jn. 3:14-16; 6:53-8 and 17:21 which connect immortality with sharing his life and union with him, and on the Pauline idea (1 Cor. 15: 50-55 etc.,) that death has beenconquered by Christ and in him we can change our mortal nature for one that is immortal?

[1]Denzing-Schonmetzer, Enchiridion 902, cited in the Catechism of the Catholic Church, s. 365.

[2]Statue: Met Z 1029a3-5, cf. Phys 1 191a25-6, Phys 2 194b24-5; sphere: Met Z 1033a24-b16, cf. Met H  1045b25-8; De Gen An 1 729b18-19; house: Met  H 1043a8-16, 32-3; bed: Phys 1 191a9, cf. De Part An 1 640b23-5.
[3] Met H 1042b16-20.
[4] Met H 1043b5-6.
[5] Met E 1025b30-1026a3, cf. Phys 2 194a5-6.
[6] De Anima 2 413a20-b13; 414a4-21.
[7] Ibid., 414b123
[8] See Aristotle’s De Anima in Focus, ed. Michael Durrant, London, Routledge, 1993, especially Richard Sorabji’s contribution “Body and Soul in Aristotle”, 162-96.
[9] So, as I understand her, K.W. Wilkes in Physicalism, London, Routledge & Kegan Paul, 1978; and I think interpretations attributing physicalism to Aristotle go back to Alexander of Aphrodias’s De Anima ed. I Bruns, Berlin 1887 2.10-25.
[10] De Anima 1 407b27-408a18.
[11] In The Physical, the Natural and the Supernatural, London, Sheed and Ward, 1998, Ch. 5, and Being Reasonable about Religion, forthcoming from Ashgate, Ch. 13.
[12] He regularly speaks of“capacities of soul”, e.g. De Anima 2 414a29; 3 432a15. For existence apart from the body the chief texts are 2. 413a5-7; 3 430a22-5.
[13] So Bernard Williams, Problems of the Self, Cambridge, Cambridge University Press, 1973, 73: “If there are any merits to the quasi-Aristotelian model of consisting of for the relations of persons and bodies (and I am doubtful of them) it certainly [my emphasis] cannot be combined consistently with the possibility of disembodiment.” Similarly Charles Kahn in “Aristotle on Thinking”, in Essays on Aristotle’s De Anima, ed. Martha C. Nussbaum and Amelie Oksenberg Rorty, Oxford, Clarendon Press 1992, 359-79. For a slightly more nuanced view, see Jonathan Barnes, “Aristotle’s Concept of Mind,” in Proceedings of the Aristotelian Society, 72 (1971-2), 101-14.
[14] See Quaestio Disputata de Anima, art. 1; Summa Theologiae 1.76.1, and for the fullest argument, Summa Contra Gentiles 2.86. I offer a detailed commentrary on the SCG chapter in Whose Aristotle? Whose Aristotelianism? ed. R.W. Sharples, Alderstot, Ashgate 2001, 63-77.
[15] Problems of the Self, 71-2.
[16] Met Z 1033a24-b19
[17]Among attempts to wrestle with the difficulty are: P. Moraux, “A propos du nous thurathen chez Aristote,” in Autour d’Aristote, studies offered to  A. Mansion, Louvain, University of Louvain, 1955, 255-95; Charles Lefevre, Sur l’evolution d’Aristote en psychologie, Louvain 1972; David Balme, Aristotle’s De Partibus Animalium 1 and De Generatione Animalium1(with passages from 2. 1-3), Oxford, Clarendon Press, 1972; and I give my own views in “Aristotle on the Place of Mind in Nature”, in Philosophical Issues in Aristotle’s Biology, ed. Allan Gotthelf and James G. Lennox, Cambridge, Cambridge University Press, 1987, 408-23.
[18] De Anima 2 414a23-4. De Gen An 2 736b1-2 implies that an embryo becomes a human being only after becoming sentient.
[19] For instance Charles Kahn, “Aristotle on Thinking.”
[20]Denzinger-Schonmetzer 800, cited in the Catechism of the Catholic Church, 327.
[21]‘Isn’t this what it is to die: for the body to exist all on its own apart from the soul, and the soul to exist all on its own apart from the body?’ (Phaedo  64 c). The model of the weaver is developed at Phaedo 87.
[22] Timaeus 34-5, 37, 41. The Demiurge made them not out of nothing but out of the materials, essential for intellectual thought, Being, Same and Other.
[23] Gorgias 524-6.

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