[4.9.7] St Thomas Aquinas on the Human Soul

St Thomas Aquinas (1225 – 1274 AD), in his works Summa TheologiaeSumma Contra Gentiles, and Disputed Questions on the Soul, elaborates on the faculties and processes working in the human soul:

  • The distinctively human vital activity (see [4.9.6]) is cognition, “and thus spiritual rather than corporeal since intellect neither is nor directly uses a corporeal organ.”
  • Cognition involves and depends on sense perception, which has corporeal organs as substrate. So, the proper objects of cognition come to the intellect only through bodily organs.
  • Some aspects of the external sensation are beyond reason’s control since reason itself has no control over the presence or absence of external things. Appetite, the natural inclination to certain external things (e.g., food, sex, etc.) depends on the presence of these external things.
  • However, internal senses are not directly dependent on external things, because with the help of the will “passions can be stirred up or calmed down by applying certain intellectively cognized universal considerations to the particular occasions or objects of the passions, and reason exercises just that sort of control.” The medium of control is phantasms, which manipulates the imaginative power.

The following UML Use Case diagram presents Aquinas’s model of the human soul:

Aquinas on human soul
FacultyRelated use caseRelations
COGNITIVESecond operation: acquire intellective COGNITION of the properties, accidents, and dispositions associated with the thing’s essence.
“the cognition of quiddities [essences] will partially depend on this second operation, and on reasoning as well: ‘the human intellect does not immediately, in its first apprehension, acquire a complete cognition of the thing. Instead, it first apprehends something about it – viz., its quiddity, which is a first and proper object of intellect; and then it acquires intellective cognition of the properties, accidents, and dispositions associated with the thing’s essence. In doing so it has to compound one apprehended aspect with, or divide one from, another and proceed from one composition or division to another, which is reasoning’. The resultant full-blown intellective cognition may be either theoretical or applied.”
includes First operation: acquire COGNITION of essences of things from phantasms through abstraction
COGNITIVEAcquire theoretical COGNITION of things.
“The resultant full-blown intellective cognition may be either theoretical or applied [practical].”
inherits from Second operation: acquire intellective COGNITION of the properties, accidents, and dispositions associated with the thing’s essence
COGNITIVEAcquire practical COGNITION of things.
“The resultant full-blown intellective cognition may be either theoretical or applied [practical].”
inherits from Second operation: acquire intellective COGNITION of the properties, accidents, and dispositions associated with the thing’s essence
COGNITIVEFirst operation: acquire COGNITION of essences of things from phantasms through abstraction.
“intellect’s ‘first operation’ consists in the formation (by agent intellect in possible intellect) of concepts of external objects […]. But since the proper objects of the first operation are identified as the quiddities, the essential natures [essences], of things […]
His account of intellect’s first operation depends on our recognizing that a child’s first acquisition of the concept of a star differs only in degree from the most recondite advance in astronomy’s understanding of the nature of a star. Quiddities, the proper objects of intellect’s first operation and, in just the same respect, the objects of the culminating cognition of nature may helpfully bethought of, then, as proper objects of both inchoate and culminating (alpha and omega) intellective cognition.” thought of, then, as proper objects of both inchoate and culminating (alpha and omega) intellective cognition.”
includes INTERNAL SENSES process sensory impressions; create and store phantasms
WILLWILL exercices control over appetite.
“We can see that will exercises some control of the relevant sort, because a human being, as long as he or she is not aberrantly behaving like a nonrational animal, ‘is not immediately moved in accordance with the irascible and concupiscible appetite but waits for the command of will, which is the higher appetite’.
[…] “intellectively cognized good moves will […] The kind of control exercised by a cognitive rational faculty (standardly identified in this role as practical reason, strictly speaking, rather than intellect).”
extends Acquire practical COGNITION of things
INTERNAL SENSESINTERNAL SENSES process sensory impressions; create and store phantasms. “Internalized sensory impressions, the ‘sensory species,’ are transmitted to ‘internal senses’ which store the sensory species and process them in various ways. Our principal concern with the internal senses now is with one of the roles of the one Aquinas calls ‘phantasia’: producing and preserving the sensory data that are indispensable for intellect’s use, the ‘phantasms’ […]
The likenesses that are identified as sensory species and phantasms may be literally “likenesses”: images – realizations of the material forms (colors, sounds, textures, etc.) of external objects in different matter, the matter of the external/internal sensory apparatus of the human body. And, in keeping with the formal-identity theory, the sensory species, at least, are likenesses that lose none of the detail present in the external senses themselves (which, of course, vary in sensitivity among individuals and from one time to another in the same individual […]
Phantasms are likenesses of particular material things re-realized in physical configurations of the organ of phantasia, which Aquinas located in the brain. Although the forms presented in the phantasms have been stripped of their original matter, the phantasm likeness is particularized by its details, the external object’s original individuating matter being ‘represented’ by features of the phantasm. Phantasms themselves, then, are not proper objects of intellective cognition, although they are indispensable to it.”
includes Corporeal things make physical impressions on the corporeal organs of ‘the EXTERNAL SENSES’
EXTERNAL SENSESCorporeal things make physical impressions on the corporeal organs of ‘the EXTERNAL SENSES’
which have both ‘proper objects’ (colors for sight, sounds for hearing, and so on) and ‘common objects’ (shapes for sight and touch, and so forth). […]
A sense organ is affected by a sense-perceptible thing, because to sense is to undergo something. For that reason the sense-perceptible thing, which is the agent [in sensation], makes the organ be actually as the sense-perceptible thing is, since the organ is in a state of potentiality to this [result]”
External senses are:  touch, sight, hearing, smell and taste.
APPETITESensory APPETITE provides inclination to things.
“The human soul of course involves natural appetites (for instance, for food of some sort), […] The appetitive power associated with sensory cognition is one we share with nonhuman animals – a cluster of inclinations (passions) to which we are subject (passive) by nature.”
extends Corporeal things make physical impressions on the corporeal organs of ‘the EXTERNAL SENSES

Sources

  • All citations from:  The Cambridge Companion to Aquinas, CAMBRIDGE UNIVERSITY PRESS, Edited by  Norman Kretzmann and Eleonore Stump, 2010
  • McInerny, Ralph and John O’Callaghan, “Saint Thomas Aquinas”The Stanford Encyclopedia of Philosophy (Summer 2018 Edition), Edward N. Zalta (ed.)

First published: 22/10/2020

[4.9.6] St Thomas Aquinas on the Composition of the Human Being

St Thomas Aquinas (1225 – 1274 AD), in his book Summa Theologiae, explains the structure of the human being and of the soul:

  • Humans (like other living beings) have vital activities, like nutrition, growth, sense perception. Intellection is a specific human vital activity. Principles of life are explanations of the vital activities, e.g., eyes are the principle of sight.
  • Human organs/body and soul are principles of life. The soul can not be reduced to the function of any organ/body.
  • The human is a composition of body and soul, following the Aristotelian hylomorphic structure (see [1.3.7]).
  • The human soul is the substantial form (see [4.9.1]) of the human.
  • The human soul is incorporeal, subsistent, and immortal.

The following OntoUML diagram presents Aquinas’s explanation of the structure of the human being:

Aquinas on the composition of the human being
ClassDescriptionRelations
HumanA human being, rational animal.has VitalActivity
HumanBodyA human body. is exclusive part of Human
BodilyOrgan“Of course, eyes must be included in a correct explanation of vision – and, he might have said, skin in the explanation of touch, roots or stomachs in explanations of growth, and so on. That is, vital activities typically do have bodies [BodilyOrgans] among their principles. And since a principle of a particular vital activity may indeed be considered a principle of life (although only in that particular respect and to an appropriately restricted extent), it may be granted that some bodies-such as a living animal’s normal eyes – are principles of life. It is in that special, limited sense that the ancient materialists were on the right track. But no one, Aquinas thinks, would call an eye (or a root, or a stomach) a soul. So, he says, some principles of life clearly are bodies, but those that are aren’t souls.”is PrincipleOfLife; is exclusive part of HumanBody
HumanSoul“In order to inquire into the nature of the soul, we have to presuppose that [human] ‘soul’ (anima) is what we call the first principle of life in things that live among us; for we call living things ‘animate’ [or ‘ensouled’], but things that are devoid of life ‘inanimate’ [or “not ensouled”] (Aquinas, Summa Theologiae)
“Therefore, the first principle of life in a living body, its soul, is no bodily part of that body, but rather its form, one of the two metaphysical parts of the composite of matter and form
that absolutely every body is. […]
Aquinas thinks of the human soul not as three nested, cooperating substantial forms, however, but as the single form that gives a human being its specifically human mode of existence, including potentialities and functions, from its genetic makeup on up to its most creative talents. […]
We have already seen Aquinas arguing that no soul considered as the ultimate (or first) intrinsic principle of a corporeal creature’s vital activities can be identified with anything corporeal. And since he here expressly identifies the soul of a human being with the principle of the distinctively human vital activity of intellection, we could have anticipated his claim that that principle must be incorporeal. Like the human hand, the human soul is in the human being not as heat is in a coal but as a part is in a whole, and so it is ‘capable of subsisting on its own’ […] the soul’s status is subtler and loftier than the hand’s. […] unlike the hand or any other bodily part of the rational animal, the human soul ‘as the [substantial] form of the body has the role of fulfilling or completing (perficiens) the human species’ – that is, the soul is not only the rationality but, indeed, the full rational animality of the human body, specifying that corporeal thing as a human being. Without the soul that body is a corpse, which can be called a human body only equivocally.”
is PrincipleOfLife; is part of Human
Subsistency“he reveals not only what distinguishes human beings from all other animals but also what makes the human soul peculiar: its status as ‘subsistent,’ a necessary condition for its existing apart from the body whose form it is. […]
According to Aquinas, the subsistence of the human soul follows from this strong thesis of its incorporeality. The vital activity of intellective cognition, which distinguishes the human soul from all other terrestrial souls, is one that it performs ‘oil its own (per se), in which the body does not share,’ not even to the extent of supplying an organ for the activity. But nothing can operate on its own in this strong sense except something ‘that subsists on its own.’ A glowing coal, which does subsist on its own, can warm something else; but heat, an accidental form whose real existence is utterly dependent on its occurring in some matter, is just for that reason incapable of warming anything on its own. The human soul, therefore, is ‘something incorporeal and subsistent’ (ST Ia.75.2c).”
characterizes HumanSoul
Immortality“Aquinas’s subsistence thesis, which clearly is incompatible with materialism of any sort, brings with it both an advantage and a difficulty for his theory of the soul. On the positive side, it establishes a necessary condition of immortality: if the distinctively human, personal aspect of the human animal is something incorporeal and subsistent, biological death need not be the death of the person. The human soul’s subsistence on its own is the philosophical basis for a reasoned account of personal immortality.”characterizes HumanSoul
PrincipleOfLifePrinciples of life (principia) are explanations of vital activities.relates Human with VitalActivity; (explains VitalActivity)
VitalActivity“the presence in living things of certain distinctive activities, which, because they naturally imply life (vita) at some level or other, are called “vital” [activities]– for example, growth or cognition.”

Sources

  • All citations from:  The Cambridge Companion to Aquinas, CAMBRIDGE UNIVERSITY PRESS, Edited by  Norman Kretzmann and Eleonore Stump, 2010
  • Kerr, Gaven : “Aquinas: Metaphysics”Internet Encyclopedia of Philosophy
  • McInerny, Ralph and John O’Callaghan, “Saint Thomas Aquinas”The Stanford Encyclopedia of Philosophy (Summer 2018 Edition), Edward N. Zalta (ed.)

First published: 15/10/2020