Who Was St Thomas Aquinas? The Key Ideas of the Philosophy of Thomism

Thomas Aquinas is the founder of a religious and philosophical doctrine of Thomism. What are the key ideas of this theory?

Jan 26, 2023By Viktoriya Sus, MA Philosophy

st thomas aquinas philosophy thomism


St Thomas Aquinas was a philosopher who lived in the 13th and 14th century. Today, he is considered one of the most important thinkers in the history of western philosophy. In addition to this, Thomas Aquinas is one of the most authoritative religious philosophers; he combined the Christian doctrine, primarily the ideas of Saint Augustine, with the philosophy of Aristotle. His philosophy, known as Thomism, is still widely studied and discussed today. In this article, we will discuss some of the basic ideas of Thomism and how they might be relevant to modern life.


Who Was St Thomas Aquinas?

carlo crivelli St thomas aquinas painting
St Thomas Aquinas, Carlo Crivelli, 1476, via The National Gallery.


Thomas Aquinas was one of the most famous philosophers and theologians of his time. He was also one of the most influential religious figures of the Middle Ages. Aquinas is considered a follower of Aristotle, and he managed to combine in his works the religious and philosophical views of his predecessor.


Thomas Aquinas was born in Italy in 1224. His father had the title of count and lived in a castle near Naples. The family wanted Thomas to become an abbot at a monastery not far from the castle. At the age of five, the boy was sent to a Benedictine monastery and lived there for almost ten years. Later, he was accepted to study at the university for four years. There, Thomas Aquinas got acquainted with the teachings of the Dominicans and, at the end of his studies, decided to join their order.


But Aquinas’ decision violated the family’s plans, and the future philosopher was kidnapped. Thomas was imprisoned in a fortress, where he spent two long years. In 1245, after Aquinas was released, he still became a member of the Dominican Order. He then went to study at the University of Paris, where he became a student of Albert the Great.

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Three years later, the future famous theologian, together with his teacher, went to the university in Cologne, where he spent two years. Finally, he returned to the Dominican monastery in 1252, but just four years later he was sent to teach theology at the University of Paris, where his first works appeared.


Francisco Zurbarán thomas aquinas painting
The Apotheosis of St. Thomas of Aquino, Francisco de Zurbarán, 1631, via Wikimedia commons.


In 1259, Aquinas was called by the Pope to Rome and was appointed as an adviser on theological issues. Thomas spent the next decade teaching in Anagni and Rome. In parallel, he was working on theological and philosophical writings. In 1269, Aquinas again found himself in Paris, where he fought with Siger of Brabant and with the Arab interpreters of the teachings of Aristotle. Thomas ensured that the works of Aristotle, translated by the Arabs, were banned.


In 1272, the famous treatise On the Unity of the Intellect Against the Averroists was published. Then, the philosopher was asked to come to Italy, where he was appointed as head of the new Dominican school in Naples. But a year later, Aquinas was forced to leave teaching due to poor health.


In 1274, Thomas Aquinas was supposed to attend a church council, but he died on the way there. In 1277, the Archbishop of Paris recognized some of the works of Thomas Aquinas as heretical; the philosopher was accused of excessive intellectualism. But despite all, the interest in his works only increased until the entire Catholic world recognized him. Thomas Aquinas began to be called the Prince of Philosophers and the Angel of the Schools.


In 1323, the Pope canonized Thomas Aquinas. His memory is honored on January 28. Today, the relics of the saint are in Toulouse.


The Origins of Thomism and Its Main Ideas

thomas Aquinas Summa theologiae book
An excerpt from the Summa Theologiae, Thomas Aquinas, 1482, via Wikimedia commons.


Thomism is a school of thought that stresses the importance of reason and tradition. It is, of course, named after St Thomas Aquinas. Thomism has been influential within the Catholic Church and has also been taken up by Anglicans, Lutherans, and Calvinists. Aquinas’ Summa Theologica, a document of religious studies dating back to the Middle Ages, is still influential and highly referenced today by the Catholic Church.


The philosophy of Thomism is based on the belief that reason and faith are both necessary to achieve true knowledge. It means that Thomists acknowledge there is a natural order to things that can be known through reason. At the same time, revelation from God is required to know certain truths about God and morality. The main ideas of Thomism are that God is the ultimate source of knowledge and that human beings can know things about God through reason and revelation.


Thomism also emphasizes the need to harmonize faith and reason and to use both in our search for truth. Finally, Thomism holds that there is an objective moral order that we can discover through reason. This philosophy has significantly impacted Western thought and has been a major influence on the development of Catholic theology.


Thomists also hold that humans are rational and social by nature and that we should use our reason to pursue truth and the good. Furthermore, Thomists believe in the existence of objective moral values and that we have to uphold these values. However, Thomists believe that true happiness is only achievable in the afterlife.


The Unity of Religion and Philosophy

author unknown st anselm portrait
St Anselm, Author unknown, via the National Portrait Gallery.


“I believe in order that I may understand.” 


This statement by the medieval philosopher Anselm of Canterbury became the motto of a new science – scholasticism. Scholasticism was engaged in the unification of religious faith and knowledge and tried to substantiate the dogmas of faith from the point of view of philosophy. Representatives of this philosophical trend believed that the path to God is not only faith but also a rational understanding of the laws of the universe.


Scholasticism reached its peak in the work of St Thomas Aquinas. He believed there are no contradictions between philosophy and religion; they complement each other and form a unity. The world is the creation of God, and, therefore, it carries the mystery of the Divine plan, which we can try to unravel.


In what ways can this be done? First, with the help of reason. It is not a straight path and will not give us full understanding because the human mind’s capacity is limited. Nevertheless, it can be used to draw closer to God. Thus, for all its importance, philosophy is still secondary to religion. St Thomas Aquinas called philosophy “the servant of theology.”


The second way to comprehend the great plan of God is faith. The original concept of the teachings of Thomas Aquinas was divine revelation, something that eludes the human mind but is necessary for the soul’s salvation.


Wisdom, according to Thomas Aquinas, is the highest knowledge about God. The philosopher singled out three types of wisdom: the wisdom of grace, the highest of all; the wisdom of theology, based on faith but using reason to understand; and metaphysical wisdom, whose instruments are reason and knowledge.


Aquinas on Matter and Form

author unknown st thomas aquinas painting
Saint Thomas Aquinas, Author unknown, 1690-1695, via Google Arts & Culture


Even though St Thomas Aquinas sought to reconcile faith and knowledge, he considered the mystical path of knowledge to be more significant. If a contradiction arises between faith and reason in some positions, it means that reason is mistaken because faith, based on Divine revelation, cannot be mistaken. But most often, the philosopher believed, contradictions arise not because philosophy is mistaken but because philosophers cannot correctly apply reason to religion.


Thomas Aquinas himself knew how to use the achievements of philosophy to explain the questions of the universe without conflicting with religious teachings. To explain being, he largely used Aristotle’s theory of form and matter. Every existing thing is a unity of form and matter. Matter itself is non-specified, and objects exist only because of form. The form is the final cause of everything. The individuality of things and phenomena appears due to the combination of the principle of form and constantly oscillating unstable matter.


The matter is the “weakest form of being,” the furthest from Divine grace. This definition of Thomas Aquinas became fundamental in scholastic science and shaped its attitude towards matter. God is the only true being. Everything else is created by Him, and all objects are manifestations of His essence. There is a hierarchy of beings; on the upper step, closest to God, are the angels. But they do not have independence either, and they are also the Creator’s inventions.


The Place of the State in Society

philipp foltz discurso funebre pericles painting
Discurso Funebre Pericles, Philipp Foltz, 1877, via WikiMedia


Like Aristotle, Thomas Aquinas was convinced that man is a social being and cannot live outside of a state. He believed the state’s goal was not only to create favorable living conditions for citizens but also to strengthen virtue and religiosity. Exploring political science, which began in ancient times, the philosopher identifies six types of government. Thomas Aquinas considers the monarchy, the aristocracy, and the potlis system, similar to the one that existed in ancient Greece, to be fair forms of social organization. Among unjust forms, he names tyranny, oligarchy, and democracy.


What is the best way to govern? St Thomas Aquinas argued that monarchy is the best form of governance because it is closest to the form of the Divine order of the world. The correct development of society and its movement towards the good and towards God is best carried out if management comes from one source.


Thomas Aquinas provided answers to many philosophical and religious questions and eliminated many contradictions between faith and knowledge. Because of this, some contemporary philosophers called him the “angelic doctor.” At the same time, “doctor” is the highest academic degree in medieval philosophy. The teachings of Thomas Aquinas are still considered fundamental by the Catholic Church.


Five Proofs for the Existence of God

raffaello Crocefissione painting
Crocefissione, Raphael, 1499-1500, via The National Gallery


Combining the teachings of Aristotle with Christian doctrine, Thomas Aquinas offered Quinque Viæ  – five proofs of the existence of God. These proofs were supposed to be an empirical way of comprehending religion, eliminating the need for spiritual revelation:


  1. Argument from motion.
  2. Argument from an efficient cause.
  3. Argument from necessary being.
  4. Argument from gradations of goodness.
  5. Argument from design.


Five proofs follow from the question of how the universe originated. Aquinas argued if you can answer this question, you will know the nature of God. The universe, he explained, is a sequence of constant changes and movement, a string of causes and effects, and the first cause is an immovable mover, a kind of first mover that is not driven by anything or anyone – God.


An object cannot move on its own; it needs an impulse from another moving object. This “motor,” in turn, is driven from its place by another impulse, and this series of movements can be traced back into time. But somewhere, this movement has to start. If it doesn’t have a start, then how does the chain of events begin? This leads him to conclude that God is the first cause of events, creating movement and not needing an impulse from another mover – he is the immovable mover.


caravaggio supper at emmaus painting
Supper at Emmanus, Caravaggio, 1601, via The National Gallery


Aquinas uses a similar argument about cause and effect: God is the “efficient cause” that brings the first effect into existence, which in turn causes another, and so on.


The third proof discusses the “possibility” of objects – many objects can exist, but do not have to. The universe cannot be entirely composed of possible objects because this opens up space, and at some point, for nothing to exist in the universe. Therefore, it is necessary to posit something necessary in itself, which does not have the cause of the necessity of something else but is the cause of the necessity of something else, and this something is God.


The fourth proof says that some things are better than others, but this comparison is meaningless until we have a final, absolute standard; and that standard is God.


Finally, in the fifth proof, Aquinas uses the Aristotelian concept of teleology, the idea that everything in the universe has a purpose and everything moves towards its final state. Objects cannot have a concept of their purpose by themselves; therefore, the Universe must be controlled by a mind that sees and determines where everything is moving – towards its end.


The Modern Relevance of St Thomas Aquinas

santi tito vision of thomas aquinas painting
Vision of St Thomas Aquinas, Santi di Tito, 1593, via Web Gallery of Art


Thomism has been greatly influential in shaping Western culture and thought, especially in the areas of ethics and natural law. In recent years, there has been a resurgence of interest in Thomistic philosophy, particularly in light of the rise of secularism and moral relativism. Many scholars and thinkers have argued that the philosophy of Thomism is more relevant than ever before in today’s modern world.


There are several key aspects of Thomistic philosophy that make it particularly relevant in today’s society. First, Thomism upholds the importance of reason and objective truth. In an age where many people are quick to dismiss anything that does not conform to their own individual worldview, the philosophy of Thomism provides a much-needed voice for rational thought and objective truth.


Secondly, Thomism emphasizes the dignity of the human person. In a world where human life is often treated as disposable and expendable, Thomism reminds us of the inherent value and worth of every human being.


The philosophy of Thomism is clearly still relevant in today’s world. Its emphasis on reason, objective truth, and the dignity of the human person offer a much-needed counterbalance to the prevailing trends of relativism and nihilism. Thomism also provides a valuable perspective on creating a just and thriving society. For these reasons, Thomism is a philosophy that is well worth studying and considering in today’s modern world.

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By Viktoriya SusMA PhilosophyViktoriya is a writer from L’viv, Ukraine. She has knowledge about the main thinkers. In her free time, she loves to read books on philosophy and analyze whether ancient philosophical thought is relevant today. Besides writing, she loves traveling, learning new languages, and visiting museums.