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Compiled by Anthony Harrison-Barbet


THOMAS AQUINAS

(1225 — 1274)

 

CHRISTIAN ARISTOTELIANISM/ THOMISM

Thomas (the 'Doctor Angelicus') was born near Naples in the castle of Rocasecca (owned by his father, the Count of Aquino). He was educated first in the Monastery of Monte Cassino and then studied Liberal Arts at the University of Naples. Influenced there by the Dominicans he joined the Order of Preachers in 1244, despite family opposition. He studied philosophy and theology at Dominican schools in Paris and Cologne (where his teacher was Albertus Magnus) and then returned to Paris, gaining his bachelor's degree in theology in 1252. While continuing advanced studies he lectured there and in Cologne. However, he did not receive his Master of Theology (teaching) degree until 1257 because of the hostility of the Paris University authorities to the mendicant orders. He was highly regarded by several popes, who sought his advice, but he refused the offer of the Archbishopric of Naples in favour of the religious life. He spent ten years from 1259 preparing commentaries on Aristotle's works, teaching again at Paris and becoming embroiled in several academic and administrative controversies. He lectured at Naples in 1272 and became a member of the papal court. He died while on the way to attend the Council of Lyons where he would have defended the use of Aristotle in theology.

 

Sources: A variety of texts are referred to in this Profile (see the Reading list), but the primary sources are Aquinas's major texts, the Summa Theologiae and the Summa Contra Gentiles. The standard reference notation has been employed: I, II, etc. are the numbers of the books within a work; 1, 2, 3, etc. are the chapters; 'q' refers to the 'questions', and 'a' to the 'articles'.

 

METAPHYSICS/ RELIGIOUS PHILOSOPHY

[1] [See especially Summary against the Gentiles, I, 4.] Philosophy for Aquinas enjoys a degree of autonomy relative to theology. He distinguishes between divinely revealed truths, for example, the doctrine of the Trinity, which are the proper concern of the dogmatic theologian, and non-revealed truths, which the philosopher examines by means of the "natural light of the reason". He also accepts that some truths, for example, that God is the creator, are both given in revelation and determinable by reason and thus falls within the purview of philosophy — as 'natural' or 'philosophical' theology. However, for Aquinas human reason has its limits: while it gives us knowledge [see sec. 6], there is much that it cannot grasp unaided about the nature of God and man's supernatural purpose. Any rationally constructed metaphysical system without reference to revelation must therefore be incomplete and imperfect. Philosophy is the 'handmaid' of theology: it is not incompatible with faith but complements it [a]. Nevertheless Aquinas stresses that man should make the fullest use of his reason, not only for the sake of acquiring knowledge itself but also, more importantly, in so far as, in conjunction with the exercise of natural virtue, it will enable him to attain to a degree of happiness, albeit imperfect, in this life.

Metaphysics is the 'First Philosophy', in the sense that it deals with what comes first in the 'real order' of things, namely Being as such, manifested in sensible reality, unlike the various 'sciences' which study different kinds of beings. It is the quest for an ultimate explanation of everything — a first 'cause' or principle [b]. But what is meant by the term 'being'? To make this clear we need to look at Aquinas's use of a number of technical terms.

(1) [Commentary on the Metaphysics, V, lect. 9, 1ff.] All particular things, whether spiritual or corporeal, are said to be beings, that is, entities (entia) or existents. An entity (ens) is 'that which is' (quod est). Aquinas distinguishes between essential being (ens per se) and coincidental being (ens per accidens). Entities possessing being in this first sense are individuals, that is, substances (for example, Socrates), and real properties (accidents), such as qualities, quantities, relations, and so on (pale, heavy, son of, for example) [ibid., V, 19; VII, 1; also Summa Theologia, I, q.29 a.2]. While paleness, heaviness, and so on, although and inseparable from and dependent on a substance for their existence, are yet real existents in their own right [c], nevertheless the being or state of affairs represented by, say, the complex 'Socrates is pale' is only coincidental. When we predicate 'pale' of 'Socrates' we are saying the accident coincides in the existent subject. [See also Quodlibetal Questions, II.]

(2) Entities have essence (essentia). In Aquinas's early writings essence is that by which a thing is what it is. But later and more generally he thinks of it as that which determines the nature or 'quiddity' ('whatness') of an entity, that which makes it a particular kind of being [ibid; also On Being and Essence].

(3) He also uses the term 'esse'. Esse (existence or 'present actuality') is an 'act' of being (actus essendi) by which essence has being [see also S.G., I, 22, 4]. Existence is to essence as form is to matter [sec. 2 below]. Esse and essentia are therefore distinct but correlative (esse gives being to essentia, while essentia, we may say, limits esse), and are thus inseparable in individual things. (Essences may not of course actually exist, though we can still grasp their nature intellectually. Thus we can understand what is meant by a phoenix even though no such creature exists in reality. We can perhaps talk here of a mental existence. But he rejects any notion of an essence having a prior existence — in some kind of eternal Platonic realm ). Existence for Aquinas is an 'accident' in the sense that it is the actuality of any substance — it is not an accident 'in itself' [Quodlib., II, a. 3] [d].

(4) Individual being is composed of actual and potential being [On Power I, l; see also Comm. Metaphys V, lectio 9, 13]. 'Actuality' and 'potentiality' relate to the degree to which an entity has been fully realized or fulfilled in accordance with its nature. Actuality is thus prior to potentiality ontologically, in the sense that the becoming of a thing only makes sense with reference to what it is to become (an acorn becomes an oak tree, for example). It follows that existence is superior to essence in so far as actuality is superior to potentiality [e].

(5) Aquinas also uses the term 'esse' to express the truth of a proposition, as when we say 'it is true that Socrates exists' or 'it is a fact that Socrates is pale' [Comm. Metaphys. V, lectio 9, 11-12]. The truth (which Aquinas calls esse ut verum) of such judgements does, however, depend on what actually exists. Indeed true and existent, he says [On Truth q.1 a.2, 1], are 'convertible' terms. He thinks of truth as a cognitive power (awareness) implicit in a relation of conformity of 'adequacy' (aedequatio) of a thought (as individualization of a form in the intellect) to the individualization of the form in the world [f].

Essence, existence, truth, and beauty for Aquinas are essential attributes of being. He calls them transcendentals [On Truth, q.1 a.1 Whereas substance and the various accidents such as quality, quantity, and the like are categories which apply to particular kinds of being, the transcendentals apply to all types or degrees of being. They are not predicates in that they are already themselves attributes or principles of being. In addition to essence, existence, and truth Aquinas identifies other transcendentals: one or unity (which is "undivided being"); distinctness, in so far as being in revealing itself as a something implies some other thing; and the good, which Aquinas understands as the object of desire for all things and is manifested in a harmonious relation to the will [g].

[2] Finite beings. [See Comm. Metaphysics, VIII lect. 2; also S.T. I q.66 aa. 1 & 2.] What makes an individual a human being, or a particular thing red, heavy, and so on? According to Aquinas it is, respectively, a substantial and an accidental form. That feature of a substance which is 'informed' is its 'prime matter'. It is the form which actualizes the matter as potentiality to give rise to the individual thing. In the case of substances the (substantial) form and the matter together constitute its nature (hylomorphism): but Aquinas confines hylomorphism to the corporeal world [a]. Prime matter cannot of course exist on its own without being 'informed': it is itself only potentiality to all forms. The matter is the principle of individuation [b]. Socrates and Plato are different bits of matter but having the same human form — which although formally identical in each person is nevertheless a distinct individual in that it 'informs' a particular piece of matter. Aquinas also argues in favour of there being only one substantial form in any substance. And he rejects any doctrine of potential forms of non-spiritual things ('seminal reasons', for example) as prior to prime matter — which in itself lacks act [c]. While form and matter are inseparable in the corporeal world, Aquinas says that between the created and embodied souls of men and the uncreated infinite God there are immaterial, created but disembodied pure forms — angels, each of which is also uniquely specific (there being no matter to individuate them).

Aquinas identifies several different kinds of change. We can talk of a change of position in space. Of more interest, however, are changes of accidents and changes of substance [d]. The change of colour of a leaf in autumn from green to red is an example of the former. In such cases we have an enduring individual substance losing one accident but acquiring another. Changes of substance occur when a given 'piece' of matter takes on a different substantial form. Consider a tree. When the tree dies the matter remains but is redistributed and becomes the material of other substances — air, plants growing in the soul, animals, and so on. As for angels, although they are immaterial they still have the capacity for non-substantial change.

Individual beings and events in general have the tendency to move from possibility to actuality. Aquinas talks here of such potentiality as active, having existence in the subject, and as 'first actuality'. (This is to be contrasted with potentiality as 'second actuality' [e], which is a potentiality arising out of and dependent on the functioning of the former. Socrates's potentiality to commit suicide by drinking hemlock would be an example.) The transition from possibility to actuality is closely connected with Aquinas's account of causation [See On the Principles of Nature and On Causes.] The matter a thing is made out of is the material cause (or 'causal factor'). That which makes the thing what it is, gives it its characteristic shape and nature, is the formal cause. The efficient cause is the agency which brings about a change (turning a lump of stone into a piece of sculpture, for example). Lastly, there is the final cause. This is the goal or end (telos) towards which an action is directed, its function or purpose (the sculptor has it in mind to produce this particular work of art). The actuality, we may say, is the 'goal' or purpose of the potentiality [f]. The end is finality of being.

[3] The nature of God. [See especially S.G., I 13.]. All finite things are beings and have being. God, however, as infinite is not a being but is absolute transcendent Being, separate from His creation. In God alone existence is included in essence. His nature is 'act itself' (ipsum esse); it belongs to His essence to be. He is also the eternal, free, 'necessary being', the ultimate final and formal cause. And in so far as he is a simple being there are no distinctions in him as between intellect and will [a]. This raises problems about the relationship of finite beings to God and of the meaning of finite 'being' to infinite 'Being'. As to the former Aquinas appeals to the concept of participation [see. for example, S.T. I 44, 1; S.G., I 22, 9; also Comm. on Boethius's De Hebdomadibus, 2]. All finite beings participate in existence in general (esse commune) — to varying degrees according to their place in the 'hierarchy of being'. Esse commune participates in the divine existence or Being ('subsistent existence' — esse subsistens), who contains within Himself and knows the divine ideas, that is, His ideas of all things he has created. In so far as these ideas, as 'exemplary forms', share in the diivine essence they are not distinct from each other. Plurality lies in God's knowledge of them (considered as rationes) [b]. Aquinas avoids pantheism, because whereas God is Being, finite created things are not; they only 'have' it in the sense that they are actualized within the limits imposed by their essentiae. It follows that 'Being' (and its transcendental attributes) as applied to God is neither a univocal nor an equivocal term. Rather, for Aquinas, it is used analogously. [See On Truth, q.2 a.11 and S.T. I q.13, aa.1-6 & 12; S.G. I 34] [c]. He argues that when we apply the term 'being' or some other quality both to God and to a finite being we are not using them in the same sense, but neither are the senses totally different. To illustrate analogical usage he gives the example of the sun's heat. We call hot both the sun itself and the heat generated by it. He in fact distinguishes between what he calls 'Analogy of Proportionality' and the 'Analogy of Attribution'. By means of the first we move from a statement about the way in which the qualities of a created being are related to its nature to a statement about how the attributes of uncreated Being (God) are related to its nature. This involves an extrapolation of a relationship from finite being to infinite Being. The difficulty here, Aquinas recognises, is that this does not tell us anything about what God is actually like. So it is necessary to extend the analogy by attributing to God properties experienced in ourselves. Thus we may talk of human wisdom or fatherhood and then apply these terms to the relationship we say obtains between us and God. This presupposes for Aquinas that there is a relation of causal dependence between creature and creator. Indeed the concept of causality is central to his proofs for God's existence.

Aquinas rejected Anselm's proofs on the grounds that he had moved illegitimately from the realm of concepts or thought to the realm of being [d]. He supposed instead that the existence of God as the ultimate final cause could be demonstrated by natural reason, starting from our experience of the existing real world [e]. His arguments are called the Five Ways [On Power, III 5c; S.G., I 13; S.T. I q. 2, a.3.]

(1) The argument from motion or change (efficient causation). We observe change everywhere. This has to be explained, that is, we must find a cause which possesses the 'perfection' (property, characteristic) to pass on to the thing which is changed (the effect). A thing cannot change itself; it cannot at the same time both possess and gain a property. So motion has to be produced by something else. But there cannot be an infinite chain of "intermediate causes". So there has to be an unchanged First Cause, namely, God; otherwise there would be no change to impart.

(2) The argument from causation in general. This is similar to the first argument. The fact that there is causation in general in the world requires a First uncaused Cause — again because of the impossibility of an unending chain.

(3) The argument from contingency (possibility) and necessity. Many things we observe in Nature are generated and decay, cease to be. Their existence is contingent and not necessary [e]. If all things were like this, there would have been a time when nothing existed, in which case there would be nothing existing now. So something must exist of a necessity which it has of itself and does not get from something else. Otherwise, once again, there would be an infinite regress.

Aquinas says God created the world freely in time out of nothing as a direct manifestation of His Goodness. He does not in fact deny that the world may in fact be eternal, but he says it cannot be proved philosophically one way or the other, though he rejects it as a matter of faith [see S.T. I q.10, aa.1,4; On Power, III 17]. And it seems that, while the first three 'proofs' are based on the alleged impossibility of an infinite sequence of contingent causes, there would be no contradiction in asserting both that the world is eternal and that there can be no infinite series of causes. We may conceive of the possibility that series of dependent events (for example, one's existence by virtue of one's parents, and their parents before them, and so on) may be endless, but we still have to account for the existence of that total infinite series [f]; and, for Aquinas, an explanation in the strict sense requires a first principle which brings about change but is itself unchanged. This is God, the prime unmoved mover — not in a temporal sense but in the ontological order.

(4) The argument from the gradation of things [g]. Some things, Aquinas says, are more good, more true, and so on than others. Comparative states require there to be superlative states, that is, there must be a best, a truest, and so on, which act as standards for all things in the hierarchy. There must therefore be an ultimate being in which all these absolutes are combined. This is the One or God.

(5) The teleological argument [h]. We can see in the activity of all natural things and processes an end or purpose, whether or not they have awareness. Those that lack awareness, however, are directed by beings that are aware, that possess a mind. Ultimately there must be a single intelligence which directs all things, in other words God.

[4] Evil, human freedom, and God's providence [S.G., III 10 and 97-8; On Evil, III 1-2, and VI; On Evil, VI; S.T. I q.83 a.1 and q.103 aa. 7-8; see also Comm. on Aristotle's Peri Hermeneias, lect. 14]. Now if God has created and directs all things, how can we account for the presence of evil? Is this compatible with His omniscience and omnipotence? The world as God's creation is necessarily good. But as God's goodness and power are infinite we can certainly conceive of his being able to create a better world, that is, one from which certain kinds situations or events had been omitted. So why did he not do so? According to Aquinas we finite beings cannot know what lay behind God's decision to create as he did. However, while recognising evil as real Aquinas says it is a privation, in the sense that it is an absence or deficiency of goodness in human nature, but that this is a consequence of man's free choice. God knows all future events by virtue of their being coexistent in eternity and thus foresees human actions. To that extent they might be supposed to be predetermined. However, although in that sense necessitated, man's actions remain contingently free considered from the temporal standpoint, and for the sake of that freedom and its proper use — to love him and to do His will — God permits even evil actions. As for physical or natural evil, this is a necessary consequence of the existence of sentient creatures living in a dynamic changing universe [a]. Aquinas seems in effect to be saying that only in a static universe could there be no earthquakes, disease, and so on. The universe as a whole is good. Moreover, man's suffering can be borne with God's assistance.

 

PSYCHOLOGY

[5] [S.T. I qq.75-90; On the Soul, I; S.G., II 58-90; Comm. on Aristotle's 'Peri Psuche'; On Truth, q.8 a.6.] Plants can grow, take in food, reproduce. This is because they have a vegetative principle or 'soul'. Animals have a sensitive 'soul' which allows them, additionally, to perceive, feel, and move around. But man not only can do all these things but also has distinct intellectual and volitional faculties by virtue of his possession of a rational soul. Nevertheless this is single and unitary [a] — assimilating the vegetative and sensitive functions. The faculties or powers are subdivided and analysed in some detail by Aquinas. Thus, he distinguishes at the sensory level five external functions (sight, hearing, taste, smell, and touch); four internal functions: 'common sense' (which involves the grasping in perception of the whole object), imagination, memory, and particular 'cogitations' of individual things; and two sensory appetites comprising respectively six 'concupiscible' and five 'irascible' appetites — the former (for example, love, hate) being tendencies towards or away from what is felt to be good or evil; the latter (for example, fear, anger) tendencies to meet perceived danger by attack, retreat, or acceptance. At the cognitive level the intellect (or understanding), which is responsible for apprehending, judging, and reasoning about 'universals', is divided into the active intellect and the passive intellect [On Truth, q.10 aa.4-6; S.T. I q.84 aa.1 & 6, and q.86 a.1]. These are not separate intellects but rather different functions of the one intellect in the individual soul [b]. Aquinas also identifies intellectual appetites, which are either (i) natural tendencies to approve of, for example, justice, and which are adjudged as good without qualification; or (ii) willed movements towards or away from things which are judged to be partly desirable or undesirable. The deliberating will for Aquinas is subordinate to intellect [c]; and he says that while man necessarily wills the end of his actions (happiness) he has free will in that he can choose the means to that end. Despite the language of 'powers' or 'faculties' Aquinas stresses that it is the whole man, the animated or 'ensouled' body which thinks, acts, desires, perceives, and knows [d]. But in so far as the rational soul has the capacity to know bodies in general (unlike, say, vision and hearing, which are dependent on a particular sense organ) it must, he says, be immaterial and spiritual, a single 'subsistent form' of the body, and therefore is incorruptible. It follows that it possesses personal immortality [On the Soul, 14; S.T. I q.75 a.6] — for which man has a natural desire, but he does not believe the survival of the human person can be established by philosophical argument [e]. (A resurrected body is also required if the immortal soul is to realise its capacity to inform the body after the latter's death: but again acceptance of this is a matter of faith.) Accordingly he argues against the idea of a single universal human agent intellect (monopsychism) [f], as this would be inconsistent with the survival of individual thinking souls.

 

KNOWLEDGE

[6] [S.T. I qq.79-85; On Truth, q.10. aa.4-6.] For Aquinas the human intellect has as its primary object essences of being — in material things [S.T. I, q.12. a.4] [a]; and knowledge is an activity of the ensouled body as a whole [a]. But he says the rational soul cannot be affected directly by material things. So how does he account for knowledge? He distinguishes three operations of the intellect. The first is simple apprehension (intelligentia indivisibilium — 'understanding of non-complex things'), an abstractive capacity by means of which it can form or grasp the 'essences', that is, common features of things. The second is judgement (compositio et divisio — 'putting together and dividing'). This involves the attributing of properties to things and gives rise to propositions — bearers of truth or falsity. Lastly he talks of reasoning (ratiocinatio). Here the mind structures syllogistically the propositions obtained by means of the second operation and attains either certain or probable conclusions. Complete and certain 'seeing' of the truth of something, which includes both conceptualization and judgement, constitutes knowledge (scientia). 'Cognition' which is the result of non-demonstrative dialectical or probable reasoning constitutes 'opinion'. (Faith, like scientia — and in contrast to opinion or belief — requires an 'assent' to its object but differs from knowledge in that the will is required to effect the assent because the truth of the object is not adequately 'seen' by the intellect) [b].

All knowledge is grounded in sense-experience and derivative memory images: "there is nothing in the intellect which was not first in the senses" [S.T. I q.1. a.9]. The exterior senses (sight, hearing, and so on) are concerned with the perceiver's own body. Corporeal objects in general are the proper object of the interior senses — the 'common sense' and the imagination through which 'phantasms' (perceptions, images, memories), representing external objects, arise [c]. The 'active' or agent intellect 'illuminates' (metaphorically speaking) the phantasms in the passive intellect and then abstracts from them what Aquinas calls 'intelligible species'. (The human intellect having its own 'natural light', Aquinas has no need of a divine illumination to obtain certain knowledge n though this light may perhaps be conceived of as a vestige or remnant of the divine.) The intelligible species are, as it were, formal 'likenesses', which are potentially universal aspects of the phantasms [S.T. I q.85 a.1], and are non-material — as is the intellect. "Whatever is received is received after the manner in which the recipient exists" [On Truth, q. 10, a.4]. What he means is that the cognising soul is 'assimilated' to the cognised object in so far as the object's particular form enters the soul as a universal intelligible species. [See ibid., aa. 4, 5; and, for example, ST I q.17, a. 3; q.75, a.5.] As objects of thought they are said to have 'intentional existence' (esse intentionale) [d]. Presented to the 'passive' intellect as species impressa — Aquinas talks of the agent intellect as 'turning' (conversio) towards the phantasms [S.T. I q. 83, a.1] — the universal elements become species expressa or universal concepts. These concepts, which have real existence only in so far as they are individuated in natural things [On the Soul, aa.l & 2] are the means whereby the forms of material objects are cognised by the intellect. Knowledge for Aquinas is thus of particulars, although it is indirect, being gained through knowledge of the universals (forms, essences) in them. Moreover, this latter knowledge is of universals as the formal element in the particulars. In so far as universals do not exist apart from particulars they are not in themselves proper objects of knowledge; and considered as 'abstracted' ideas they are known only in a secondary sense. They are, however, real in so far as they are grounded in extramental being; and in this respect Aquinas is a 'moderate realist' [e]. It follows from his account that he rejects innate ideas except in the trivial sense that the human mind has the capacity for abstraction and formation of concepts [f]. Likewise the soul can have no knowledge of itself except in its acts of abstracting intelligible species. Knowledge for Aquinas is thus ultimately dependent on sense-perception as converted into phantasms. Nevertheless he makes it clear that while in this life the mind needs the body as its natural object, it is capable of being active qua mind even when separate from the body, and indeed it can then know itself and other souls perfectly [g].

[7] Knowledge of God [Comm. on Boethius's De Trinitate, q.6 a.3; S.T. I, qq.86-8; S.G. I 14.] Granted that God's existence can be proved, can we know anything of His nature? If, as Aquinas says, knowledge is ultimately dependent on sense-experience, does this mean we can have no knowledge of God (or of other non-corporeal beings) — at least in this life? His answer is that it is particular material things which are approached through the senses; the rational soul is directed towards Being in general. And although while embodied it cannot know non-corporeal beings directly it does have imperfect analogical knowledge revealed through sensory experience. He identifies both an affirmative way (per excessum) and a negative way (per remotionem) [a]. The former involves attributing to God without limit properties possessed by a finite being. However, in so far as God cannot be directly known we may also say He possesses various properties a finite being has, but not to a lesser degree. This is the negative approach. Aquinas seems to advocate the use of both ways. [See also sec. 3 above.]

 

ETHICS

[8] [See, for example, Comm. on Aristotle's Ethics, 9-10; S.T. I-ii qq.18-20, 55-6, 90-4; S.G., III 114-38.] All acts of a rational human being, when done deliberately and freely, are directed to the attainment of some end perceived as good, such as wealth, knowledge, pleasure. But none of these 'goods' fully satisfies the human will. According to Aquinas there is only one final end which can give man 'well-being', or 'happiness' (felicitas), namely, the universal good, which he identifies with God. To do good and avoid evil is the fundamental principle of practical reasoning and is intuited intellectually by means of the quality of 'synderesis' [a]. To achieve this end one's actions must be morally good, and this requires three factors to be taken into account: (i) [S.T. I-ii q.18 a.2] their objective must be 'fitting' and agree with "the reasonable order of life" (just as the basic goodness of a natural thing is provided by its specific form — which makes it the kind of thing it is); (ii) [ibid., a.8] 'special circumstances' — these are comparable to the qualities which characterize the specific nature given to man by his substantial form; (iii) [ibid. aa.4 & 6] the end (finis operantis), that is the motive or agent's intention, intended by the will. This formally specifies the act pointing to its objective (its purpose, finis operis). The test of the moral goodness or rightness of an action is the mean, to achieve which one must avoid excess or defect. What constitutes a mean in a given situation will depend on the circumstances and motives or intentions. Chastity, for example, when pursued for selfish reasons (for example, self-aggrandisement), might seem to be a defect (licentiousness being the corresponding excess): but if undertaken, say, for the love of God it is a mean. By adhering to the mean a man will acquire the moral virtues, which when combined with the intellectual virtues of understanding and prudence will develop practical judgement, that is, moral conscience [b] — "a sort of dictate of reason... application of knowledge to action" [S.T. I-ii q.19 a.5] and this will enable him to live rightly. To perceive the mean presupposes conformity to the 'order of reason' as manifested in the natural law which is grounded in human nature and is concerned with guiding man towards the achieving of his natural end, that is, his 'intellectual form' (his final and all-embracing value). This end is reasonable and good in so far as it agrees with reason which is directing the will towards it. But Aquinas allows that some actions (for example, taking a walk) may involve nothing at all related to reason, as contrasted with, say, almsgiving which is by definition good in so far as it is agreeable to reason. They are therefore morally 'neutral' [ibid. q.18 a.8]. (Natural law is contrasted with divine positive law, which is concerned with man's supernatural end, and God's eternal law, which orders the universe as a whole [S.T. I-ii qq.90ff.] ). Natural moral law, Aquinas says, depends not on God's will but on the divine reason or essence in so far as God sees the law of human nature in the eternal idea of man he possesses within himself; and thus it is in general not open to alteration [c]. What exactly is the universal good and in what sense is it God? Man, says Aquinas, has a natural desire for God which can be realized only in a 'beatific vision' of him. To have knowledge of God's essence is of course not possible through philosophical demonstration; and the knowledge implicit in 'vision' is more than can even be revealed to us through faith. To achieve it supernatural grace is required. [See Comm. on Peter Lombard's Sentences, Book 4, 49.]. However, he wished to keep moral theology (and faith) separate from philosophy (and reason). [On the problem of evil see sec. 4.]

[9] [See, for example, ST I q.81, 2 & 3; II q.77 a2; I-ii qq.22-48.] If morality and the achieving of happiness by aiming at the universal good is a matter of reason and knowledge, how does Aquinas account for weakness of will? How is it that a man might perceive what is properly good for him and yet act in a way contrary to his best interests? Aquinas distinguishes between involuntary actions such as those in which one reacts instinctively out off, say, fear, and voluntary actions where one is rationally aware of ends and the means required to realize them. The problem of weakness applies essentially to the latter. In such cases the reason of the 'incontinent' man is hindered or obscured by passion and therefore fails to direct the will in the manner appropriate for the achieving of the right end [a]. Reason must therefore seek to harness the 'irascible' appetites — inclinations which assist us to overcome whatever inhibits our 'concupisciple' appetites (inclinations to seek what is appropriate or to avoid what is harmful). Proper exercise of the will thus presupposes cultivation of the reason reinforced by the exercise of moderation in one's actions in the light of natural law.

 

POLITICAL PHILOSOPHY

[10] [Especially On the Governance of Rulers and S.T. I-ii passim.] Man is by nature a social and political animal — as is evident from his possession of language. However, he also needs society to provide a framework in which individual talents can be developed and the virtuous life achieved. Now, given the egocentric tendencies of many people, a society needs to be ordered and controlled by a wise government (just as the soul controls the passions and appetites). In so far as human nature was created by God, government is ultimately justified by Him; and the ideal governance would be one which provides for the needs of its citizens, secures peace and order in the interest of the common good. This would be a perfect society. Nevertheless, says Aquinas, even such a society must be subordinated to the authority of the Church in matters spiritual or supernatural [a]. This is because man's natural end cannot be achieved without God's grace. The role of the legislator is to define and apply the natural law to specific concrete situations, and thereby to enact human positive law which regulates the social behaviour of the people. Laws which are unjust, in that they are not derived from natural law, may be disobeyed in conscience. But it can never be right to disobey just laws, or laws which run counter to the divine eternal law [b] (revealed through Christ). There are of course many possible kinds of government. Aquinas identifies three good types (law-abiding democracy, aristocracy, and monarchy), and three bad ones ('demagogic' democracy, oligarchy, and tyranny). He says monarchy is the most 'natural' in that it involves the rule of one over many (as God rules over his creation). But a wise monarch is not readily found; and Aquinas thinks that in practice a 'mixed' constitution (similar to Aristotle's 'polity') combining the best features of democracy and aristocracy is preferable [c].

 

AESTHETICS

[11] Beauty for Aquinas exists objectively in things in so far as they reflect or participate in the absolute beauty (pulchritudo) of God [a] [Commentary on the Divine Names IV, 5-6]. — Like Truth it is a transcendental attribute of Being [a]. We have a 'disinterested apprehension' of the beauty in things through our cognitive perception; and we see it as an object of pleasure [ST 1a.q.5.a.4] (just as good is seen as the object of desire). But he argues that the 'delight' we experience in the beautiful is different from that evinced by truth or goodness in that it is a characteristic of the whole person. Beauty, as formal cause (as contrasted with the good as final cause), is characterized by (a) 'proper proportion', that is, harmony, (b) 'integrity' or perfection, and (c) 'clarity' or brilliance [1a.q.39.a.8] [b]. As for art, Aquinas says this is a 'habit' — an application of the intellect to practical action, and involves "right reason in making things" (just as in ethics it is a matter of exercising one's right reason in doing things). The function of art is to imitate nature, because nature is the reflection of God's intellect [c].

 

CRITICAL SUMMARY

Generally regarded as the greatest medieval thinker, Aquinas covered a vast range of philosophical issues, and his thought is notable for its depth, acuity, judicious balance and consistency. He drew on Neoplatonic elements, but his philosophy is thoroughly Aristotelian — the power of the Greek philosopher's writings being appropriated in support of Christian theology. Three significant features may be singled out.

(1) The separation of faith and reason. While Aquinas regarded philosophy developed through reason alone as incomplete without revelation, with him reason achieved autonomy not only in philosophy but also in natural theology.

(2) The emphasis on sense experience and the natural world rather than on an 'inner light' and the supernatural world, and on individuality rather than the universal, as the starting-point for knowledge. This is reflected in particular in (a) Aquinas's recognition of the parallelism between essence and existence, potency and act, and matter and form in individuals. The individual is no longer a reflection of the universal but is regarded as a composite entity in its own right. Aquinas thus claims to have solved what were perceived to be a number of problems in Plato's metaphysics. Being and becoming are understood in terms of act and potentiality. Form actualizes matter; matter is the individuating principle. Universals are real but exist only in individual things; and the individual does not contain a plurality of forms. Moreover, the soul is now the form of the body, although it remains dependent on matter. The centrality of individuality is seen also in (b) Aquinas's ethics. The will is subordinated to the intellect. Emphasis is therefore placed on the individual's deliberation and choice rather than on a will 'primed' by divine grace.

(3) His notions of metaphysical 'participation' and analogical predication of being, which is neither equivocal nor univocal, and his attempt to blend Platonic and Aristotelian traditions in his approach to the divine ideas should also be noted as making an important contribution to the debate concerning the relationship of created beings to God.

Aquinas's assumptions and approach do of course lay his system open to objections. Augustinians criticized him for breaking the direct connection between God and his creatures. Knowledge is now to be acquired not through divine illumination but through abstraction by the active intellect. God is no longer to be known directly; knowledge through analogy is imperfect. Moreover, in his rejection of the ontological argument Aquinas will not allow a transition from the 'idea' to the 'real'. His own 'Five Ways' for proving God's existence, all of which are a posteriori and start from sense experience, can themselves be criticized for at best only establishing the existence of a first cause prime mover, not of a personal God. These arguments are in any case questionable. Given that contingent beings are those which can cease to be, is there a necessary being at all? While he allows that an infinite series of dependent causes may be possible (though not philosophically provable), it remains an open question whether such a putative series itself requires a prime mover or first cause. And would such a first cause have to possess the divine qualities demanded by Aquinas? His accounts of the relation between faith and reason and of the scope of metaphysics were also to be challenged later by Duns Scotus and Ockham. Nevertheless, once the ecclesiastical authorities had overcome their reservations and were satisfied that Aquinas's use of the new Aristotelian scholarship did not lead to 'false' teaching, 'Thomism' became the 'official' philosophy of the Catholic Church — despite a rearguard action by the Augustinians. And in recent years there has been a renewed interest in his metaphysics, theory of knowledge, and philosophy of mind among many philosophers who owe no allegiance to the Church and indeed are in some case non-theists. As for his ethics, this exhibits the strengths and weaknesses of Aristotle's moral philosophy. But whether Aquinas's relocation of Aristotle's ethics in an explicitly Christian framework results in an improvement on the Greek master, or whether the numerous philosophical problems that arise (concerning, say the existence of God, or the possibility of a 'natural' law) make it less easy to defend Aquinas's ethical system, remain open questions.

 

READING

Aquinas: [of many writings] De Ente et Essentia (1253) (On Being and Essence); Expositio super Librum Boethii de Trinitate (1257-8) (Commentary on Boethius's de Trinitate); Summa de Veritate Catholicae Fidei contra Gentiles (1259-64); (Manual against the Gentiles: On the Truth of the Catholic Faith); Summa Theologiae (1265-73) (Manual of Theology); see also Quaestiones Disputatae (Disputed Questions) n De Veritate (1256-9) (On Truth), De Potentia Dei (1265-7), De Malo (1269-72) (On Evil), De Anima (1269-70) (On the Soul), and Questiones Quodlibetales (1256-72) (Quodlibetal Questions); and his various commentaries — on the Neoplatonic Liber de Causis (1272) (Book of Causes), Peter Lombard's Sentences (1254-6), Boethius's De Trinitate and De Hebdomadibus (1257-8), and (1266-72) on Aristotle's Peri Hermeneias (On Interpretation), Metaphysics, and Peri Psuche (On the Soul), and other Aristotelian texts... There are numerous editions of English translations: in particular, A. Pegis & others (Summa Contra Gentiles), and T. McDermott (Summa Theologiae n abridged); T. McDermott (ed.), Aquinas: Selected Philosophical Writings; C. J. F. Martin (ed.), The Philosophy of Thomas Aquinas: Introductory Readings; and see also R. McKeon, op. cit., vol II, ch. 3.

 

Studies:

Introductory

F. C. Copleston, Aquinas.

B. Davies, The Thought of Thomas Aquinas.

A. Kenny, Aquinas.

More advanced

B. Davies, 'Thomas Aquinas', in J. J. E. Garcia (ed.), A Companion to Philosophy in the Middle Ages.

A. Kenny, Aquinas on Mind.

J. Weisheipl, Friar Thomas D'Aquino. His Life, Thought, and Works.

J. F. Wippel, Metaphysical Themes in Thomas Aquinas.

Collections of essays

A. Kenny (ed.), Aquinas: A Collection of Critical Essays.

N. Kretzmann and E. Stump (eds), The Cambridge Companion to Aquinas.

 

 

CONNECTIONS

Thomas Aquinas

 

Metaphysics
[1a] Reason compatible with faith but has limits, and faith has primacy

   Augustine

   Avicenna

Anselm

   Averroes

   Maimonides

   Wm of Auvergne

   Albert

   Bonaventura

Duns Scotus

Ockham

Locke

Leibniz

Russell

[1i]

[5d]

[1a]

[1a]

[1a]

[1a]

[1a]

[1a]

[1a]

[3c]

[2r]

[5i]

[5c]

 

[1b 6a] Metaphysics: study of ultimate Being

   Aristotle

   Albert

   Avicenna

Henry of Ghent

Duns Scotus

Ockham

Suarez

[13a]

[1a]

[1a]

[1a]

[1a]

[1e 3a]

[1a]

   

 

Note also general rejection of metaphysics:

 

 
   

   Bacon (Francis)

   Hume

[1a d 2a d]

[5a]

 

[1c; cf. 2a d 3e]

Essential and contingent being; individuals, substances; qualities, relations as real existents

   Aristotle

Duns Scotus

Ockham

Suarez

Descartes

Locke

[13a g]

[2c]

[3d 3e 3g]

[2d 3a 4a]

[2c 3a]

[2b 2d]

 

[1d] Existence (esse) actualizes essence (essentia); essence not prior; inseparable in individuals

   Aristotle

   Boethius

   Avicenna

   Averroes

   Maimonides

Henry of Ghent

Duns Scotus

Ockham

Suarez

[13a]

[1b]

[1c]

[2a]

[2e]

[1b]

[2b]

[3a]

[2a b]

 

[1e; cf 2a] Individual being as actualized potentiality; existence 'superior' to essence

   Aristotle

   Avicenna

   Averroes

   Albert

[5b 13a 14b]

[2a]

[2a c g]

[1h]

 

[1f] Esse as truth of proposition; adequacy of thought to form    Aristotle [2a]

 

[1g 11a] Transcendentals and categories

   Plato

   Aristotle

   Ps-Dionysius

Duns Scotus

Suarez

[15b]

[4a b]

[1e]

[1b 6a]

[1b]

 

[2a] Form 'actualizes' prime matter: makes individual substance a kind or particular thing; no universal hylomorphism — only in corporeal things

   Aristotle

   Augustine

   Avicenna

   Averroes

   Maimonides

   Albert

   Bonaventura

Henry of Ghent

Duns Scotus

Suarez

Locke

[13c 14a b]

[4a]

[1f 3e]

[2g]

[2f]

[1h 1k]

[4a b]

[1i]

[2c f 2e]

[2b]

[2d]

 

[2b] Matter (potentiality) as individuation factor

   Aristotle

   Avicenna

   Albert

   Bonaventura

Henry of Ghent

Duns Scotus

Suarez

[14a]

[3e 4b]

[1j]

[4g]

[1i]

[2g]

[2c]

 

[2c; see also 3a] No plurality of forms or seminal reasons

   Aristotle

   Augustine

   Avicenna

   Albert

   Bonaventura

Henry of Ghent

Duns Scotus

Ockham

[14a]

[4e]

[1f 3e]

[1f]

[2a 4c f]

[1h]

[2d 2h]

[5a]

 

[2d e; see also 6d] Change; potentiality and first/ second actuality

   Aristotle

   Avicenna

   Albert

[5b 14b]

[2a]

[1h]

 

[2f] Causation: the four 'causes'

   Aristotle

Ockham

Suarez

Locke

Hume

[6a sec. 9]

[2c 3h]

[1f]

[2g]

[1h]

 

[3a] God: formal and final cause, prime mover; essence included in his existence; absolute Being and transcendent — separate from creation

   Aristotle

   Boethius

   Avicenna

   Maimonides

   Albert

Henry of Ghent

Ockham

Suarez

Leibniz

Brentano

Royce

[12e]

[1c]

[1d 3a]

[2a]

[1b]

[1b]

[4f]

[1a d]

[5a]

[5a]

[1f]

 

[3b; cf. 6e] Divine Ideas; God's knowledge of his creation; participation, hierarchy of being; modified 'exemplarism'

   Plato

   Aristotle

   Posidonius

   Boethius

   Augustine

   Avicenna

   Averroes

   Maimonides

   Alexander of Hales

   Albert

   Bonaventura

Henry of Ghent

Duns Scotus

Ockham

[2c]

[13d e]

[1a]

[1d]

[2c 4a 4c]

[3d e]

[2g]

[2f]

[3a]

[1g 1h 1i]

[2a 3c]

[1d]

[3c]

[4d]

 

[3c; cf. 7a] Predication of God's attributes: analogical — neither univocal nor equivocal

   Boethius

   Avicenna

   Averroes

   Maimonides

   Albert

   Bonaventura

Henry of Ghent

Duns Scotus

Ockham

Suarez

   Spinoza

Berkeley

[1d]

[1e]

[2b]

[2b]

[1c]

[3a]

[1g]

[1c 3b]

[3b 4b]

[1c]

[2f]

[3b]

 

 

Proofs for God's existence:

 

 
[3d] Rejection of ontological argument

   Anselm

   Albert

   Bonaventura

Duns Scotus

Ockham

Descartes

Locke

Leibniz

[1e]

[1d]

[1c]

[3a]

[4a]

[3c]

[2l]

[5b]

 

[3e] Arguments from the real sensible, physical world

Henry of Ghent

Descartes

   Berkeley

[1j]

[3b]

[3a]

 

[3e] i argument from motion/ change

   Aristotle

   Maimonides

   Albert

Duns Scotus

Ockham

Suarez

Locke

 

[12e]

[2c]

[1d]

[3a]

[4a]

[1g]

[2l]

 

  ii causation in general

   Aristotle

   Avicenna

Duns Scotus

Ockham

Suarez

 

[12e]

[1d e]

[3a]

[4a]

[1g]

 

  iii contingency and necessity

   Avicenna

   Maimonides

Duns Scotus

Ockham

Brentano

[1d e]

[2c]

[3a]

[3g 4a]

[5a]

 

[3f; cf. 3b] Infinite series; eternity of world — not provable philosophically; world freely created in time by God (accepted on faith); total infinite temporal series may be known to and dependent on God

   Aristotle

   Augustine

   Avicenna

   Averroes

   Maimonides

   Albert

   Bonaventura

Henry of Ghent

Duns Scotus

Ockham

Royce

[12c e]

[4b 6a]

[3a]

[2e 2g]

[2d]

[1e g 1f]

[2b 2c]

[1f]

[3e]

[4c]

[1f]

 

  Arguments 4 and 5:  
[3g] iv proof from degrees of being

   Aristotle

   Augustine

   Anselm

   Bonaventura

Ockham

   Descartes

[12f]

[3a-c]

[1c]

[1b]

[4a]

[3b]

 

[3h] v. teleological argument (from design)

Ockham

Leibniz

   Kant

Brentano

[4a]

[5e]

[10e]

[5a]

 

[4a] God's knowledge of the future; evil as privation: providence human freedom; natural evil intrinsic to dynamic universe

   Aristotle

   Chrysippus

   Augustine

   Abelard

   Avicenna

   Maimonides

   Bonaventura

Duns Scotus

Ockham

Suarez

Leibniz

   Berkeley

   Schelling

Brentano

[9b 10d]

[4b]

[5a b]

[3a]

[3g 3h]

[3a b]

[7d]

[3f]

[4e 6b]

[5a]

[5h]

[3e]

[6d]

[4b]

 

Psychology
[5a; cf. 5d] Rational soul — distinct faculties, but unitary

   Aristotle

   Augustine

   Avicenna

   Averroes

   Albert

   Bonaventura

Henry of Ghent

Duns Scotus

Ockham

Descartes

[15a-c]

[7a 7b]

[4a 4b]

[3d]

[2a]

[5b 5a c]

[1h]

[4a 4b]

[5a c]

[3d 3g]

 

[5b] Passive and active intellects — not separate but different functions

   Aristotle

   Avicenna

   Averroes

   Maimonides

   Albert

   Bonaventura

Duns Scotus

Ockham

[15d]

[4c]

[3b]

[4a]

[2c]

[5b d]

[4b]

[5c]

 

[5c] Will subordinate to intellect

   Aristotle

   Augustine

   Bonaventura

Henry of Ghent

Duns Scotus

Ockham

[15f]

[7b]

[6c]

[1e 2d]

[3d 4d]

[6b]

 

[5d; cf. 5a] Ensouled body as whole man in thinking, desiring, acting

   Aristotle

   Augustine

   Bonaventura

Duns Scotus

Ockham

Descartes

[15b]

[7a]

[5b]

[4a]

[5c]

[3g]

 

[5e] Rational soul as single form of body; personal immortality

   Aristotle

   Augustine

   Avicenna

   Averroes

   Maimonides

   Albert

   Bonaventura

Henry of Ghent

Duns Scotus

Ockham

Descartes

Locke

Brentano

[15b d e]

[7a 7a]

[4b 4d]

[3d 3e]

[4c 4c]

[2b]

[5a c 5e]

[1h]

[4c]

[5a b]

[3d g 3g]

[2e 2h]

[3b]

 

[5f] No single universal agent/ active human intellect

   Aristotle

   Avicenna

   Averroes

   Maimonides

   Albert

   Bonaventura

Duns Scotus

Ockham

[15d e]

[4d]

[3b e]

[4c]

[2c]

[5d]

[4b]

[5c]

 

Knowledge
[6a; cf. 1b 5d] Knowledge of being (essences) primary; and by ensouled body as a whole

   Aristotle

Duns Scotus

Ockham

Locke

[15b]

[1a 5a]

[2b]

[2o]

 

[6b] Knowledge (scientia): certain cognition, conceptualization and judgement; as against belief (opinion)

   Aristotle

   Augustine

   Hume

   Brentano

[16 a b 17a c 20b]

[1b d 2b]

[2a]

[1b c]

 

[6c; cf. 6f] Knowledge starts in sense-perception; the 'common sense'; imagination and 'phantasms'

   Aristotle

   Augustine

   Avicenna

   Bonaventura

Henry of Ghent

Duns Scotus

Ockham

Descartes

Leibniz

Brentano

Ortega y Gasset

[16b d]

[1b]

[5a]

[6a b]

[2a c]

[5a]

[2b]

[2c]

[6c]

[2c]

[2b]

 

[6d] Active intellect illuminates phantasms in passive intellect and 'abstracts' intelligible species; no divine illumination; soul 'assimilated to cognised object; 'intentional' existence of intelligible species

   Aristotle

   Augustine

   Avicenna

   Averroes

   Maimonides

   Albert

   Bonaventura

Henry of Ghent

Duns Scotus

Suarez

Descartes

Malebranche

Brentano

[16c d e]

[2a]

[1b 5a]

[3c]

[4a b]

[3a b]

[6b 6c]

[2b]

[5b d]

[3b]

[2c]

[3d e]

[1a]

 

[6e; cf. 3b] Universals: individuated in particulars — not divine archetypes; knowledge of universals

   Plato

   Aristotle

   Boethius

   Abelard

   Avicenna

   Albert

Henry of Ghent

Duns Scotus

Ockham

Suarez

Locke

Malebranche

Brentano

[1b c]

[13d e 16a d e]

[1i]

[2a]

[1b]

[1i]

[2b]

[2g 5d]

[1e 2d 3e]

[2e 3c]

[1b 2o]

[3e]

[3c]

 

[6f] No pre-existing innate ideas — only capacity

   Plato

   Aristotle

   Augustine

   Bonaventura

Henry of Ghent

Duns Scotus

Ockham

Descartes

Locke

Leibniz

[sec 8]

[16b]

[2b]

[6a]

[2c]

[5a]

[2b]

[2b]

[2a]

[6c]

 

[6g] Soul — no self-knowledge except when abstracting or disembodied

   Aristotle

Duns Scotus

Ockham

Brentano

[16d]

[5e]

[2e]

[2c]

 

[7a; cf. 3c] Knowledge of God: imperfect analogical; negative and positive ways

   Ps-Dionysius

   Avicenna

   Maimonides

   Albert

   Bonaventura

Duns Scotus

Ockham

Locke

[1b]

[1e 5e]

[4f]

[3c]

[6c]

[3b]

[2f ]

[2l]

 

Ethics/political philosophy
[8a 1g] The good; happiness lies in the vision of God as infinite goodness

   Plato

   Aristotle

   Avicenna

Ockham

[11e f]

[18a-d]

[2b]

[6d]

 

[8b] Requirements for moral action; intentions and circumstances; acquisition of the mean; reason and conscience

   Aristotle

   Chrysippus

   Augustine

   Abelard

   Bonaventura

Duns Scotus

Ockham

[19b 20a-f 21a]

[6d]

[8c]

[3b]

[7a c]

[6b]

[6c]

 

[8c] Natural law as reflection of God's eternal law and unchangeable; morally 'neutral' actions (when relation to reason irrelevant)

   Seneca

   Augustine

Duns Scotus

Ockham

Suarez

Locke

[2b]

[8d]

[6c]

[4g 6a]

[6a]

[3b c]

 

[9a] Weakness of will

   Aristotle

   Descartes

[21b]

[3i]

 

[10a] Man: social and political animal, language user; society needed for achievement of virtue; role of Church

   Aristotle

   Seneca

   Augustine

   Machiavelli

Suarez

   Hobbes

[22a-d]

[2c]

[9b]

[sec. 1]

[6b]

[7g]

 

[10b] Human positive law, natural law, eternal law, and justness

   Plato

   Aristotle

   Augustine

   Machiavelli

Suarez

   Hobbes

Locke

[11c 14b]

[19c]

[9c]

[1d]

[6a]

[7e g]

[3c]

 

[10c] Limited monarchy or mixed 'polity' preferable

   Aristotle

   Machiavelli

Suarez

   Hobbes

Locke

[22d]

[1b]

[6b]

[7d]

[3c]

 

Aesthetics
[11a; cf. 1g] Beauty as transcendental attribute of Being and reflection of God

   Plato

   Ps-Dionysius

[15b]

[1e 1e]

 

[11b] Beauty — formal cause; attributes/ criteria — proportion, harmony, clarity

   Aristotle

Leibniz

[23c]

[5e]

 

[11c] Art and imitation of nature    Aristotle [23a]