Thomas Aquinas
For Aquinas, reason and faith agree: reason can prove that God exists from features of the world such as motion, causation and order, and natural law tells everyone what is right.
Placement
Synthesis of Aristotle and Christian theology: five ways to God and a theory of natural law.
Key ideas
- Five Ways
- Natural law
- Analogy of being
Teachers: Albertus Magnus
Influence
Influenced by 9
Aristotle
influenced by ✓
Aquinas made Aristotle’s philosophy of nature and the soul the framework of his theology and, chiefly in 1268–73, commented on a dozen of his works. Thomas Aquinas, Sentencia libri De anima; In Metaphysicam; Sententia libri Ethicorum; SEP “Thomas Aquinas”
Aristotle › 384–322 BCE
Augustine
influenced by ✓
Aquinas read Augustine’s doctrine of divine illumination as the God-given natural light of the agent intellect (Summa theologiae I q. 84 a. 5). Thomas Aquinas, Summa theologiae I q. 84 a. 5; SEP “Divine Illumination”; SEP “Thomas Aquinas”
Augustine › 354–430
Pseudo-Dionysius the Areopagite
influenced by
Aquinas commented on Dionysius’ Divine Names and cited him often, taking up the threefold way of affirmation, negation and eminence for naming God. Thomas Aquinas, In librum Beati Dionysii De divinis nominibus expositio; Summa theologiae I q. 13; SEP “Thomas Aquinas”
Evidence: also in InPhO · InPhO
Pseudo-Dionysius the Areopagite › c. 480–530
Ibn Sina (Avicenna)
influenced by ✓
In On Being and Essence (c. 1255) Aquinas took up Avicenna’s distinction of essence and existence, citing him often; elsewhere he rejected his necessary emanation of the world. Thomas Aquinas, De ente et essentia (c. 1255); Summa theologiae I q. 47 a. 1; SEP “Thomas Aquinas”; SEP “Ibn Sina [Avicenna]”
Evidence: also in Wikidata · Wikidata
Ibn Sina (Avicenna) › 980–1037
al-Ghazali
influenced by ✓
Thomas, like Albert, used the Latin translation of al-Ghazali’s Doctrines of the Philosophers (Maqasid, by Gundissalinus) as a source on Arabic philosophy – taking “Algazel”, whose critical frame the translators had left out, for a follower of Avicenna. SEP “al-Ghazali” (F. Griffel), section on the Latin reception; al-Ghazali, Maqasid al-falasifa, Latin Summa theoricae philosophiae (12th c.)
Evidence: also in Wikidata · Wikidata
al-Ghazali › 1058–1111
Maimonides
influenced by ✓
Aquinas engaged ‘Rabbi Moses’ on the divine names (Summa theologiae I q. 13) and agreed with him that the world’s beginning cannot be demonstrated (I q. 46). Thomas Aquinas, Summa theologiae I q. 13 a. 2, q. 46 aa. 1–2; Maimonides, Guide of the Perplexed I.51–60, II.13–25; SEP “Maimonides”
Evidence: also in Wikidata · Wikidata
Maimonides › 1138–1204
Show all (9)Show fewer
Boethius
influenced by ✓
Aquinas commented on Boethius’ On the Trinity and De hebdomadibus and adopted his definitions of person and of eternity (Summa theologiae I q. 29, q. 10). Thomas Aquinas, Super Boetium De Trinitate; Expositio libri De hebdomadibus; Summa theologiae I q. 10 a. 1, q. 29 a. 1; SEP “Anicius Manlius Severinus Boethius”
Evidence: also in Wikidata · Wikidata
Boethius › c. 477–524
Isaac Israeli
influenced by
Thomas Aquinas quoted Isaac Israeli’s Book of Definitions in Latin translation; the definition of truth as the adequation of thing and intellect that he attributes to it (De veritate q. 1 a. 1) is, however, not found there. SEP “Isaac Israeli”; Altmann and Stern 1958; Thomas Aquinas, De veritate q. 1 a. 1
Evidence: AI draft
Isaac Israeli › c. 855–955
Albertus Magnus studied with
studied with ✓
Attested by Thomas’s own hand – a manuscript of Albert’s commentary on Dionysius’ Divine Names in his handwriting survives in Naples – and by biographers who knew him; anecdotes such as the ‘dumb ox’ come from William of Tocco’s later Life. G. Théry, “L’autographe de S. Thomas conservé à la Biblioteca Nazionale de Naples”, Archivum Fratrum Praedicatorum 1 (1931); William of Tocco, Ystoria sancti Thome; J.-P. Torrell, Saint Thomas Aquinas I, ch. 2
Albertus Magnus › c. 1200–1280
Influenced 13
Meister Eckhart
influenced
Trained in the Thomism of the Dominican order, Eckhart departed from Thomas in his Parisian Questions (1302–03) by placing understanding above being in God. Meister Eckhart, Quaestiones Parisienses I (1302–03); SEP “Meister Eckhart”
Evidence: AI draft
Meister Eckhart › c. 1260–1328
Francisco Suárez
influenced
Suárez lectured on Aquinas’ Summa and wrote within the Thomist tradition, yet departed from it, denying a real distinction between essence and existence (Disputationes metaphysicae XXXI). F. Suárez, Disputationes metaphysicae (1597), disp. XXXI; SEP “Francisco Suárez”
Evidence: AI draft
Francisco Suárez › 1548–1617
Franz Brentano
influenced
Brentano introduced intentional inexistence in Psychology from an Empirical Standpoint (1874) with reference to the Scholastics, citing Aquinas’s view that the thing thought is intentionally in the thinker. F. Brentano, Psychologie vom empirischen Standpunkt (1874); SEP “Franz Brentano”; SEP “Thomas Aquinas”
Evidence: AI draft
Franz Brentano › 1838–1917
G. E. M. Anscombe
influenced ✓
Anscombe adopted Aquinas’s account of practical knowledge as ‘the cause of what it understands’ (Intention, 1957) and defended his principle of double effect (‘War and Murder’, 1961). G. E. M. Anscombe, Intention (1957); “War and Murder”, in W. Stein (ed.), Nuclear Weapons: A Catholic Response (1961); SEP “Gertrude Elizabeth Margaret Anscombe”; SEP “Doctrine of Double Effect”
Evidence: also in Wikidata · Wikidata
G. E. M. Anscombe › 1919–2001
Philippa Foot
influenced ✓
Foot turned to Aquinas, alongside Aristotle, for an account of the virtues as beneficial dispositions that correct temptations and deficiencies of human nature (‘Virtues and Vices’, 1978). P. Foot, “Virtues and Vices”, in Virtues and Vices and Other Essays in Moral Philosophy (1978); SEP “Philippa Foot”
Evidence: also in Wikidata · Wikidata
Philippa Foot › 1920–2010
Umberto Eco
influenced ✓
Eco’s thesis, Il problema estetico in San Tommaso (1956), reconstructed Aquinas’s aesthetics of proportion, integrity and clarity; his medieval studies later informed The Name of the Rose (1980). U. Eco, Il problema estetico in San Tommaso (1956; rev. as Il problema estetico in Tommaso d’Aquino, 1970); Il nome della rosa (1980); SEP “Thomas Aquinas”
Evidence: also in Wikidata · Wikidata
Umberto Eco › 1932–2016
Show all (13)Show fewer
Paulus Vladimiri (Paweł Włodkowic)
influenced
Following Aquinas on the dominion of unbelievers (Summa theologiae II-II q. 10 a. 10), Włodkowic argued at Constance (1415) that pagans’ rule and property rest on natural law. Paulus Vladimiri, De potestate papae et imperatoris respectu infidelium (1415); S. F. Belch, Paulus Vladimiri and His Doctrine Concerning International Law and Politics (1965)
Evidence: AI draft
Paulus Vladimiri (Paweł Włodkowic) › c. 1370–1435
Francisco de Vitoria
influenced
From 1526 Vitoria lectured in Salamanca on Aquinas’ Summa instead of Peter Lombard’s Sentences and developed its natural law into a law of nations. F. de Vitoria, commentaries on the Secunda secundae; Relectio de Indis (1539); SEP “School of Salamanca”
Evidence: AI draft
Francisco de Vitoria › c. 1483–1546
Bartolomé de las Casas
influenced
Las Casas argued with Aquinas’ natural law that unbelievers hold legitimate dominion and may be won to faith only by peaceful persuasion (De unico vocationis modo, c. 1537). B. de las Casas, De unico vocationis modo (c. 1537); Apologia (c. 1552); Thomas Aquinas, Summa theologiae II–II
Evidence: AI draft
Bartolomé de las Casas › 1484–1566
Sor Juana Inés de la Cruz
influenced
Sor Juana defended Aquinas, Augustine and Chrysostom against António Vieira’s sermon on the ‘finezas’ of Christ, arguing in scholastic form (Carta atenagórica, 1690). Sor Juana Inés de la Cruz, Carta atenagórica (1690); Respuesta a Sor Filotea de la Cruz (1691); O. Paz, Sor Juana Inés de la Cruz o las trampas de la fe (1982)
Evidence: AI draft
Sor Juana Inés de la Cruz › c. 1648–1695
Edith Stein
influenced
Stein compared Husserl with Aquinas (1929), translated De veritate (1931–32) and joined both in Endliches und ewiges Sein (written 1935–37; publ. 1950). E. Stein, “Husserls Phänomenologie und die Philosophie des hl. Thomas v. Aquino” (1929); Des hl. Thomas von Aquino Untersuchungen über die Wahrheit, trans. E. Stein (1931–32); Endliches und ewiges Sein (publ. 1950); SEP “Edith Stein”
Evidence: AI draft
Edith Stein › 1891–1942
Martin Luther King Jr.
influenced
King took from Aquinas the definition of an unjust law as a human law not rooted in eternal and natural law (Letter from Birmingham Jail, 1963). M. L. King Jr., “Letter from Birmingham Jail” (1963); Thomas Aquinas, Summa theologiae I–II
Evidence: AI draft
Martin Luther King Jr. › 1929–1968
Alasdair MacIntyre
influenced
MacIntyre moved from Aristotle to Aquinas, defending Thomism as able to integrate Aristotelian and Augustinian traditions of enquiry (Whose Justice? Which Rationality?, 1988). A. MacIntyre, Whose Justice? Which Rationality? (1988); Three Rival Versions of Moral Enquiry (1990); SEP “Virtue Ethics”
Evidence: AI draft
Alasdair MacIntyre › 1929–2025
Criticism
Criticized by 4
Siger of Brabant
criticised by
Siger of Brabant replied to Aquinas’ attack on the single intellect, granting points while still doubting that Aristotle could be read otherwise (De anima intellectiva, c. 1273). Siger of Brabant, De anima intellectiva (c. 1273); SEP “Siger of Brabant”
Evidence: AI draft
Siger of Brabant › c. 1240–1284
John Duns Scotus
criticised by
Duns Scotus rejected the Thomist view that matter individuates, positing a ‘thisness’ (haecceitas), and held ‘being’ univocal rather than analogical (Ordinatio II d. 3; I d. 3). John Duns Scotus, Ordinatio II d. 3 p. 1; I d. 3 p. 1 qq. 1–3; SEP “John Duns Scotus”
Evidence: AI draft
John Duns Scotus › c. 1266–1308
William of Ockham
criticised by
Ockham rejected Aquinas’ real distinction between essence and existence and the intelligible species in cognition as entities without need (Summa logicae III-2 c. 27; Reportatio II). William of Ockham, Summa logicae III-2 c. 27; Reportatio II qq. 12–13; SEP “William of Ockham”
Evidence: AI draft
William of Ockham › c. 1287–1347
Pietro Pomponazzi
criticised by
Pomponazzi argued that Aquinas’ proof of the soul’s immortality from Aristotle fails, since on Aristotelian principles the human intellect always needs the body (De immortalitate animae, 1516). P. Pomponazzi, Tractatus de immortalitate animae (1516); SEP “Pietro Pomponazzi”
Evidence: AI draft
Pietro Pomponazzi › 1462–1525
Criticizes 3
Solomon ibn Gabirol
criticised
Aquinas rejected Avicebron’s (Ibn Gabirol’s) universal hylomorphism: angels and souls have no matter, being composed only of potency and act (Summa theologiae I q. 50 a. 2). Thomas Aquinas, Summa theologiae I q. 50 a. 2; De spiritualibus creaturis a. 1; SEP “Solomon Ibn Gabirol [Avicebron]”
Evidence: AI draft
Solomon ibn Gabirol › c. 1021–1058
Anselm of Canterbury influenced by
influenced by ✓
Aquinas took over Anselm’s account of Christ’s death as satisfaction in modified form (Summa theologiae III q. 48), while rejecting his proof from the concept of God. Anselm, Cur Deus homo (1098); Thomas Aquinas, Summa theologiae III q. 48 a. 2; I q. 2 a. 1; SEP “Thomas Aquinas”
Evidence: also in Wikidata · Wikidata
criticised
Aquinas denied that God’s existence is self-evident to us: from the meaning of ‘God’ it follows only that God exists in the mind, not in reality. Thomas Aquinas, Summa theologiae I q. 2 a. 1 ad 2; Summa contra gentiles I.10–11
Evidence: AI draft
Anselm of Canterbury › 1033–1109
Ibn Rushd (Averroes) influenced by
influenced by ✓
Aquinas used Averroes as ‘the Commentator’ throughout his Aristotle commentaries, even while writing against his single intellect for all humans. Thomas Aquinas, Sentencia libri De anima; In Metaphysicam; C. Burnett, ‘Arabic into Latin’, in P. Adamson / R. C. Taylor (eds.), The Cambridge Companion to Arabic Philosophy (2005); SEP “Ibn Rushd [Averroes]”
Evidence: also in Wikidata · Wikidata
criticised
Aquinas argued that Averroes’ single intellect for all humans contradicts both Aristotle and the experience that it is the individual human being who thinks (De unitate intellectus contra Averroistas, 1270). Thomas Aquinas, De unitate intellectus contra Averroistas (1270); Summa theologiae I q. 76 a. 2
Evidence: AI draft
Ibn Rushd (Averroes) › 1126–1198
Works
- c. 1265Summa contra Gentiles
A defense of the truth of the faith by rational arguments, addressed also to those who do not accept Scripture – Thomas names Muslims and pagans.
Each individual human being thinks: against the doctrine of a single intellect.
- 1273Summa theologiae
The great synthesis: God, humanity, virtues, law – with the “Five Ways”.
Position
Thomas sought to show that reason and faith cannot truly conflict, since both come from the same God. He adopted Aristotle’s philosophy as the best account of nature and the soul, and built on it a theology that reason can partly reach: the existence of God can be shown in “five ways”, from motion, causation, contingency, degrees of perfection and order. Central to his metaphysics is the distinction between what a thing is (essence) and the fact that it is (existence); only in God do they coincide. His ethics rests on natural law, the order of practical reason that every human can know. Declared the Church’s leading theologian, he remains the reference point of Catholic philosophy.
Life & context
Born in 1225 at Roccasecca, between Rome and Naples, into a noble family, Thomas joined the Dominicans against his family’s resistance. He studied with Albert the Great in Paris and Cologne, taught as a master at the University of Paris and in several Italian cities, and wrote an enormous body of work in barely twenty years. He died in 1274 on his way to the Council of Lyon.
Further main works
- On Being and Essence (c. 1255)
Appears in
- Journey ‘The Journey of Aristotle’ · Stop 9 of 9
- Debate ‘War and Peace: When Is Armed Force Justified?’
- Debate ‘A Right to Die? Assisted Dying’
- Debate ‘Thomas Aquinas and Siger of Brabant: One Intellect for All?’
As of November 2026 · Sources · Improve this page · How Agora is made