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Thomas Aquinas

Scholastic · Europe · 1225 to 1274

Italian friar who joined Aristotle's philosophy with Christian belief. He said morality rests on a natural law that reason can discover.

What it is

Thomas Aquinas (about 1225 to 1274) was a medieval Dominican friar and theologian who reworked the philosophy of Aristotle into a system for Christian thought. He argued that reason can show a great deal about God and about human life, that faith and philosophy each have their own place, and that morality rests on natural law and on the virtues. He is often seen as the greatest thinker of thirteenth-century Europe, and his influence on later philosophy has been very large.

He was born near Aquino, halfway between Rome and Naples, into a wealthy family, and studied in Naples, where he was drawn to the newly founded Dominican order. He studied and taught in Paris and studied under Albert the Great. His two largest works are the Summa theologiae and the Summa contra gentiles. He died in 1274 and was later canonised as a saint.

The main ideas

  • Aristotle, remade. Aquinas took much of his philosophy from Aristotle, whose writings were being rediscovered in Latin translation in his day. He did not simply copy them. He rebuilt Aristotle's thought into something new that could serve Christian theology.
  • Faith and reason. He held that neither theology nor philosophy should be reduced to the other. Each has its own proper scope, and each can perfect the other. Reason can investigate what we can know naturally about God and human beings, and good theology builds on that.
  • Arguments for God. He is most famous for the five ways, five short arguments that God exists, drawn from features of the world such as motion and existence. He did not accept Anselm's ontological argument.
  • Natural law. He gave one of the earliest systematic discussions of the nature and kinds of law, including a famous account of natural law.
  • Virtue and happiness. Despite his interest in law, his ethics is centred on virtue. He wrote at length about happiness, pleasure, the passions, habit and the will, and about each of the cardinal, intellectual and theological virtues.
  • Soul, knowledge and freedom. He also developed accounts of the soul and body as form and matter, of how we perceive and think, and of the will and freedom.

What it looks like in practice

Picture someone who has to decide whether to keep a difficult promise. An Aquinas-style approach asks what a good person, with a settled habit of fairness and honesty, would do, and what the aim of a good human life asks of them. It also asks what the shared moral law, which reason can grasp, requires. The answer comes from character and from reasoning about what is good together, not from a single rule or a calculation of results.

Works and moments

  • Summa contra gentiles and Summa theologiae are his two most important works. The Summa theologiae is a long systematic treatment of theology and philosophy together.
  • Teacher and student. He studied with Albert the Great, who held that Christian faith could only benefit from a deep engagement with philosophy and science. That conviction became his own.
  • Return to Paris. In 1268 he was asked to return to Paris for a second term as master of theology.

Questions and criticism

  • Do the five ways work? Whether arguments that start from motion or existence can show that God exists has been debated for centuries.
  • Can philosophy and theology stay separate? His model gives each its own proper scope. It is fair to ask whether that works in practice when a claim belongs to both.
  • Is natural law known to all? If reason can find moral law, it is fair to ask why people so often disagree about what it requires.

Close neighbours

Aquinas takes his inspiration from Aristotle and sits at the summit of a Christian tradition that runs back through Augustine. His reworking of Aristotle provoked many later arguments and elaborations. The page on Aristotelian virtue ethics describes the ethics he drew on, and the page on theism describes the belief in God that his arguments aim to defend.

Written by epchē in our own words, and checked against independent sources on 9 October 2026. The sources are listed below.

Philosophies they belong to or are close to

Who they connect to

Influenced

  • Alasdair MacIntyre · MacIntyre later described himself as a Thomist.
  • Bartolome de las Casas · He argued from Aquinas' account of natural law and human reason, which holds for all peoples.
  • Elizabeth Anscombe · Anscombe drew on Aquinas for her account of intention and practical reason.
  • Francisco Suarez · He built his thought on Aquinas, while reshaping it for his own time.
  • John Duns Scotus · Scotus responded to Aquinas point by point while taking over much of his method.
  • Meister Eckhart · He held the same teaching post in Paris that Aquinas had held, and built on his thought.
  • Philippa Foot · Foot's Natural Goodness draws on Aquinas' account of natural ends.

Influenced by

  • Al-Ghazali · Latin translations of Al-Ghazali's summary of philosophy reached scholastic writers such as Aquinas. (scholars disagree about this link)
  • Aristotle · Aquinas wrote commentaries on Aristotle and built his moral and natural philosophy on them.
  • Augustine of Hippo · Aquinas relied on Augustine as one of his chief authorities on grace, will and the soul.
  • Averroes (Ibn Rushd) · Aquinas relied on Averroes' commentaries to read Aristotle, even where he rejected them.
  • Boethius · Aquinas commented on Boethius' theological tracts and used his definition of a person.
  • Ibn Sina (Avicenna) · Aquinas took over Avicenna's distinction between what a thing is and that it is.
  • Moses Maimonides · Aquinas cites Maimonides often, especially on how to speak about God.
  • Peter Abelard · Aquinas used the later method of setting opposing authorities side by side. (scholars disagree about this link)

Reacted against

  • Anselm of Canterbury · Aquinas rejected Anselm's argument that God's existence follows from the idea of God, and preferred proofs that start from the world.
  • Averroes (Ibn Rushd) · Aquinas wrote a treatise against the view that all humans share one intellect.

Reacted against by

  • John Duns Scotus · Scotus disagreed with Aquinas about the priority of will over intellect and about how being is said.

Runs parallel to

  • Ramanuja · Both reconcile a personal God with a systematic philosophy of the soul and world. (scholars disagree about this link)

Other Scholastic thinkers

Sources we used

  • Thomas Aquinas · Stanford Encyclopedia of Philosophy, read on 9 October 2026
  • Thomas Aquinas · Internet Encyclopedia of Philosophy, read on 9 October 2026
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