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Thomas Aquinas

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On the Coordinates: 1.2 Cosmology (Philosophical) · 1.7 Free Will and Determinism · 1.8 Natural Theology +8 more

Tommaso d'Aquino

Also known as Saint Thomas Aquinas, the Angelic Doctor, Doctor Angelicus

c. 1225 – 1274 · Roccasecca, Paris, Naples, Fossanova

Traditions: Medieval Christian

Schools: Scholasticism

In brief

Thomas Aquinas (c. 1225–1274) was an Italian Dominican friar who taught theology at the University of Paris and in Italy. He lived at the moment when the whole of Aristotle, together with commentaries by Muslim and Jewish philosophers such as Ibn Sina, Ibn Rushd and Maimonides, had just become available in Latin. He used these sources to build a systematic account of God, the world and human life, while keeping a clear line between what reason can prove and what depends on revelation. His arguments for God’s existence, his theory of natural law and his ethics of virtue are still studied and debated well beyond the Catholic Church.

In depth Last reviewed

Connections

Places
Paris taughtNaples taughtCologne studied
Journeys
Aristotle's long journey: Athens → Alexandria → Baghdad → Isfahan → Marrakesh → Paris
Tradition
Medieval ChristianScholasticism
Influences
8 sourced relationships

Life

Thomas was born around 1225 into a noble family that held the castle of Roccasecca, near Aquino in southern Italy; he was the youngest of at least nine children. As a boy he was placed at the Benedictine abbey of Monte Cassino. As a student in Naples he was drawn to the new Dominican order of preachers, and he joined it at about nineteen. His family, who had other plans for him, confined him at Roccasecca for about a year before he was allowed to go to Paris. He studied there and then, from 1248, in Cologne under Albert the Great. He held one of the Dominican chairs of theology at Paris from 1256 to 1259, then spent most of the next decade in Italy, at Orvieto and Rome, where he began the Summa theologiae. He returned to Paris for a second period as master of theology in 1268, in the middle of controversies over radical Aristotelianism, and went back to Naples in 1272. After about eighteen months there he stopped writing. He died on 7 March 1274 at the Cistercian abbey of Fossanova. In 1277 some propositions condemned at Paris seemed to touch his views; he was canonised in 1323.

Problems

  • How faith and reason relate
  • Whether God’s existence can be proved
  • How created things are composed of essence and existence
  • What the human soul is and whether it survives death
  • What law, virtue and happiness are

Core ideas

Faith and reason

Aquinas held that there are two routes to truth. Some truths about God, such as that God exists and is one, can be reached by natural reason working from what we experience. Others, such as the Trinity or the Incarnation, can be known only because God has revealed them. Since both come from the same source, they cannot truly conflict; when a philosophical argument seems to contradict faith, the argument must contain an error. This lets him take Aristotle and his Muslim and Jewish commentators seriously as philosophers. Critics ask whether a thinker who already knows the conclusion he must reach can be doing philosophy in the full sense.

The five ways

In the Summa theologiae (part 1, question 2, article 3) Aquinas gives five short arguments that God exists. Each starts from a feature of the world: things change, things are caused, things exist that might not have existed, things have degrees of perfection, and natural things act for ends. Each then argues that the series cannot go back without end and must rest on something that is not itself changed, caused or contingent. The third way, from contingency, draws closely on Maimonides. A common objection is that, even if valid, the arguments reach a first cause, not the God of religion; Aquinas spends the following questions arguing for God’s further attributes. Commentators still debate what kind of infinite series he is ruling out.

Essence and existence

In his early work On Being and Essence, Aquinas took over Ibn Sina’s distinction between what a thing is and the fact that it is. In every created thing, essence and existence are really distinct: nothing about being a horse guarantees that horses exist. Existence (esse) is the act that makes an essence real. Only in God are the two identical, so God is ‘subsistent being itself’. This gave him a way to explain why the world depends on God at every moment, not only at a beginning. He rejected, however, Ibn Sina’s account of the world emanating necessarily from God through a series of intellects.

Natural law

For Aquinas, God governs the universe by an eternal law. Rational creatures share in it in a special way: they can grasp, by reason, the goods their nature inclines them towards, such as preserving life, raising offspring, knowing the truth about God and living in society. This share in the eternal law is natural law. Its first precept, in the English Dominican translation, is that ‘good is to be done and pursued, and evil is to be avoided’ (I–II, question 94, article 2). Human laws are just when they apply natural law to particular circumstances, and a command that violates it lacks the full nature of law. Critics ask how one can move from facts about human nature to moral obligations, and whether the theory depends on its theological frame.

Works

  • Commentary on the Sentences of Peter Lombard (Scriptum super Sententiis) 1252–1256His first major theological work, written as a student teacher in Paris.
  • On Being and Essence (De ente et essentia) 1252–1256A short treatise on essence, existence and the structure of reality, drawing on Ibn Sina.In the Book corner
  • Summa contra gentiles 1259–1265A defence of Christian belief that argues as far as possible from reason alone.In the Book corner
  • Summa theologiae 1267–1273 (unfinished)His great teaching summa in three parts, left incomplete in the third part.In the Book corner
  • On the Unity of the Intellect against the Averroists (De unitate intellectus) 1270A refutation of the thesis that all humans share one intellect.
  • On the Eternity of the World (De aeternitate mundi) 1271Argues that reason cannot prove that the world had a beginning, though faith teaches that it did.
  • Commentaries on Aristotle c. 1267–1273Line-by-line commentaries, including on On the Soul and the Nicomachean Ethics.

Influences and relationships

8 sourced relationships. Open one to read why, and the source.

Shaped Thomas Aquinas 4

Thomas Aquinas shaped or answered 4

Reception

Aquinas’s work was controversial at first: some of the 219 articles condemned at Paris in 1277 seemed to touch his teachings. His canonisation in 1323 restored his standing, and a long tradition of commentary on his works, known as Thomism, grew up over the following centuries, with periods of decline and revival. He remains a central authority in Catholic thought. Today he is also read far beyond the Church: by analytic philosophers of religion working on the five ways, by natural law theorists in ethics and jurisprudence, by virtue ethicists returning to Aristotle, and by historians tracing how Greek, Islamic and Jewish ideas entered Latin thought.

Disputed interpretations

Theologian or philosopher?

Aquinas called himself a theologian, and his major works are theological. Some scholars therefore argue that his philosophy cannot be lifted out of its theological setting. Others hold that his arguments can and should be assessed on their own philosophical merits, and much analytic work proceeds this way. The SEP, while treating his theology at length, holds that it is appropriate today to count him among the philosophers.

Does the soul survive as the person?

Aquinas holds that the soul is the form of the body and that a human being is a unity of both, yet that the intellectual soul survives death. ‘Corruptionists’ argue that, for him, the human being ceases to exist at death until the resurrection, though the soul remains. ‘Survivalists’ argue that the person continues to exist, constituted by the soul alone.

Compatibilist or libertarian?

Aquinas describes the will as a rational appetite that necessarily seeks happiness but freely chooses among particular goods as the intellect presents them. Some interpreters read this as compatibilism, since choice follows the intellect’s judgement. Others read it as a libertarian view, since the will can direct the intellect’s attention and no particular good compels it.

Primary texts

  • Summa Theologica, Part I (Prima Pars) Free to read · Project GutenbergTranslation by the Fathers of the English Dominican Province, from the Complete American Edition; free on Project Gutenberg. The five ways are in question 2, article 3.
  • Summa Theologiae, I–II, question 94 (on natural law) Free to read · newadvent.orgEnglish Dominican Province translation, second revised edition (1920), free on New Advent.
  • On Being and EssenceStandard English translation by Armand Maurer (Pontifical Institute of Mediaeval Studies, 2nd ed. 1968).

Sources

Scholarly sources and reference works, free to read online.

Guides

In the Book corner

  • On Being and Essence c. 1252–1256 · Advanced
    A short treatise written in Paris in the mid-1250s, early in Aquinas's career, for his fellow Dominicans. It explains two basic terms…
  • Summa contra Gentiles c. 1259–1265 · Advanced
    A treatise in four books, written between about 1259 and 1265, also called the Book on the Truth of the Catholic Faith…
  • Summa Theologiae 1265–1274 (unfinished) · Advanced
    Aquinas's vast, unfinished summary of Christian theology, intended for beginners in theology but now thousands of pages long. It is divided into…

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Cite this page

Written and kept up to date by the Coordinates of Thought editors. Each statement was checked against the sources listed above before publishing; this page is not peer-reviewed. Last updated 26 October 2026. How to cite this site.

APA (7th edition)

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MLA (9th edition)

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Coordinates of Thought Editors. “Thomas Aquinas.” Coordinates of Thought. Last modified October 26, 2026. https://coordinatesofthought.com/thinker/thomas-aquinas/.

BibTeX

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  author       = {{Coordinates of Thought Editors}},
  title        = {Thomas Aquinas},
  howpublished = {Coordinates of Thought},
  year         = {2026},
  month        = oct,
  url          = {https://coordinatesofthought.com/thinker/thomas-aquinas/},
  note         = {Last updated 26 October 2026}
}

RIS

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TI  - Thomas Aquinas
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Where next

  1. On the Atlas · where they taughtParisSee the place, century by century, and who else was there.
  2. On the Atlas · journey of ideasAristotle's long journey: Athens → Alexandria → Baghdad → Isfahan → Marrakesh → ParisAristotle's school treatises travelled from Greek into Arabic and then into Latin over some fifteen centuries.…

Tradition: Medieval Christian philosophyThinkers A–Z