2.2: Medieval Philosophy

The rise and fall of Rome follows the golden age of ancient Greece. Greek philosophical traditions undergo assorted transformations during this period, but Rome is not known for making significant original contributions to either philosophy or science. Intellectual progress requires a degree of liberty not so available in the Roman Empire. Additionally, the intellectual talent and energy available in ancient Rome would have been pretty fully occupied with the demands of expanding and sustaining political power and order. Rome had more use for engineers than scientists, and more use for bureaucrats than philosophers.

Christianity becomes the dominate religion in Rome after emperor Constantine converts in the 4th century A.D. Plato’s philosophy provides much of the basis for what will become orthodox Catholic doctrine, more specifically known as Neoplatonism. In the 4th century, the great Christian philosopher Augustine, after a rather dissolute and free-wheeling youth, studies Plato and Neoplatonism and find’s much to make Christianity reasonable by way of these philosophical systems.

With the rise of the Catholic Church, learning and inquiry are pursued largely exclusively in the service of religion for well over a millennium. Philosophy in this period is often described as the handmaiden of theology. The relationship between philosophy and theology is perhaps a bit more ambiguous, though. As we’ve just noted in the case of Augustine, much ancient Greek philosophy gets infused into Catholic orthodoxy. But at the same time, the new faith of Christianity spearheads an anti-intellectual movement in which libraries are destroyed and most ancient Greek thought is lost to the world forever.

Through the West’s period of Catholic orthodoxy, most of what we know of Greek science and philosophy, most notably Aristotle’s thought, survived in the Islamic world. What remains of the complete works of Aristotle covers subjects as far ranging as metaphysics, ethics, politics, rhetoric, physics, biology, and astronomy, and amounts to enough writing to fill 1500 pages in the fine print translation on my bookshelf. But even this consists largely of lecture notes and fragments. Most of his polished prose is lost forever.

The Crusades, which were a series of conflicts between the Christian and Islamic world towards the end of the middle ages, offered occasion for cultural exchange, and the Crusades led to the re-introduction of Aristotle and other ancient Greek scholarship to the west. Aristotle’s philosophy and science was too carefully reasoned, systematic, and subtle to be dismissed as pointless pagan speculation. Instead, Christian thinkers in the west set out to understand Aristotle and interpret him a manner that would cohere with Catholic doctrine. St. Thomas Aquinas is the most famous philosopher to engage in this work of Christianizing Aristotle. He found ways to harness Aristotle’s metaphysical arguments in the cause of advocating the existence of a Christian God.

Aristotle’s views about the natural world quickly come to be received as the established truth in the Christian world. Aristotle’s physics, for instance becomes the standard scientific view about the natural world in Europe. Aristotle also wrote about the methods of science, and he was much more empirical than his teacher Plato. Aristotle thought the way to learn about the natural world was to make careful observations and infer general principles from these. For instance, as an early biologist, Aristotle dissected hundreds of species of animals to learn about anatomy and physiology. The Scholastics who studied Aristotle obviously did not adopt the methods Aristotle recommended. But some other people did. Galileo, Leonardo da Vinci, and Copernicus were among the few brave souls to turn a critical eye to the natural world itself and, employing methods Aristotle would have approved of, began to challenge the views of Aristotle that the Scholastics had made a matter of doctrine. Thus begins the Scientific Revolution, which informs and is informed by Modern Philosophy….

Neoplatonism in the Middle Ages

The early medieval period, which extended to the 12th century, was marked by the barbarian invasions of the Western Roman Empire, the collapse of its civilization, and the gradual building of a new, Christian culture in western Europe. Philosophy in these dark and troubled times was cultivated by late Roman thinkers such as Augustine and Boethius (c. 470–524), then by monks such as St. Anselm of Canterbury (c. 1033–1109). The monasteries became the main centres of learning and education and retained their preeminence until the founding of the cathedral schools and universities in the 11th and 12th centuries.


During these centuries philosophy was heavily influenced by Neoplatonism; Stoicism and Aristotelianism played only a minor role. Augustine was awakened to the philosophical life by reading the Roman statesman Cicero (106–43 BC), but the Neoplatonists most decisively shaped his philosophical methods and ideas. To them he owed his conviction that beyond the world of the senses there is a spiritual, eternal realm of Truth that is the object of the human mind and the goal of all human striving. This Truth he identified with the God of Christianity. Human beings encounter this divine world not through the senses but through the mind—and, above the mind, through the intelligible light. Augustine’s demonstration of the existence of God coincides with his proof of the existence of necessary, immutable Truth. He considered the truths of both mathematics and ethics to be necessary, immutable, and eternal. These truths cannot come from the world of contingent, mutable, and temporal things, nor from the mind itself, which is also contingent, mutable, and temporal. They are due to the illuminating presence in the human mind of eternal and immutable Truth, or God. Any doubt that humans may know the Truth with certainty was dispelled for Augustine by the certitude that, even if they are deceived in many cases, they cannot doubt that they exist, know, and love.

Augustine conceived of human beings as composites of two substances, body and soul, of which the soul is by far the superior. The body, nevertheless, is not to be excluded from human nature, and its eventual resurrection from the dead is assured by Christian faith. The soul’s immortality is proved by its possession of eternal and unchangeable Truth.

Augustine’s Confessions (c. 400) and De Trinitate (400–416; On the Trinity) abound with penetrating psychological analyses of knowledge, perception, memory, and love. His De civitate Dei (413–426; The City of God) presents the whole drama of human history as a progressive movement of humankind, redeemed by God, to its final repose in its Creator.


One of the most important channels by which Greek philosophy was transmitted to the Middle Ages was Boethius. He began to translate into Latin all the philosophical works of the Greeks, but his imprisonment and death by order of Theodoric, king of the Ostrogoths, cut short this project. He finished translating only the logical writings of Porphyry and Aristotle. These translations and his commentaries on them brought to the thinkers of the Middle Ages the rudiments of Aristotelian logic. They also raised important philosophical questions, such as those concerning the nature of universals (terms that can be applied to more than one particular thing). Do universals exist independently, or are they only mental concepts? If they exist independently, are they corporeal or incorporeal? If incorporeal, do they exist in the sensible world or apart from it? Medieval philosophers debated at length these and other problems relating to universals. In his logical works Boethius presents the Aristotelian doctrine of universals: that they are only mental abstractions. In his De consolatione philosophiae (c. 525; Consolation of Philosophy), however, he adopts the Platonic notion that they are innate ideas, and their origin is in the remembering of knowledge from a previous existence. This book was extremely popular and influential in the Middle Ages. It contains not only a Platonic view of knowledge and reality but also a lively treatment of providence, divine foreknowledge, chance, fate, and human happiness.

Aristotelianism in the Middle Ages

St. Thomas Aquinas

After completing his education, Saint Thomas Aquinas devoted himself to a life of traveling, writing, teaching, public speaking and preaching. Religious institutions and universities alike yearned to benefit from the wisdom of “The Christian Apostle.”

At the forefront of medieval thought was a struggle to reconcile the relationship between theology (faith) and philosophy (reason). People were at odds as to how to unite the knowledge they obtained through revelation with the information they observed naturally using their mind and their senses. Based on Averroes’s “theory of the double truth,” the two types of knowledge were in direct opposition to each other. Saint Thomas Aquinas’s revolutionary views rejected Averroes’s theory, asserting that “both kinds of knowledge ultimately come from God” and were therefore compatible. Not only were they compatible, according to Thomas’s ideology, but they could also work in collaboration: He believed that revelation could guide reason and prevent it from making mistakes, while reason could clarify and demystify faith. Saint Thomas Aquinas’s work goes on to discuss faith and reason’s roles in both perceiving and proving the existence of God.

Saint Thomas Aquinas believed that the existence of God could be proven in five ways, mainly by: 1) observing movement in the world as proof of God, the “Immovable Mover”; 2) observing cause and effect and identifying God as the cause of everything; 3) concluding that the impermanent nature of beings proves the existence of a necessary being, God, who originates only from within himself; 4) noticing varying levels of human perfection and determining that a supreme, perfect being must therefore exist; and 5) knowing that natural beings could not have intelligence without it being granted to them it by God. Subsequent to defending people’s ability to naturally perceive proof of God, Thomas also tackled the challenge of protecting God’s image as an all-powerful being.

Saint Thomas Aquinas also uniquely addressed appropriate social behavior toward God. In so doing, he gave his ideas a contemporary—some would say timeless—everyday context. Thomas believed that the laws of the state were, in fact, a natural product of human nature, and were crucial to social welfare. By abiding by the social laws of the state, people could earn eternal salvation of their souls in the afterlife, he purported. Saint Thomas Aquinas identified three types of laws: natural, positive and eternal. According to his treatise, natural law prompts man to act in accordance with achieving his goals and governs man’s sense of right and wrong; positive law is the law of the state, or government, and should always be a manifestation of natural law; and eternal law, in the case of rational beings, depends on reason and is put into action through free will, which also works toward the accomplishment of man’s spiritual goals.