Albertus Magnus, St.St. Albertus Magnus, detail of a fresco by Tommaso da Modena, c. 1352; in the Church of San Nicolò, Treviso, Italy.Alinari/Art Resource, New York
Albertus’s observations and discoveries in the natural sciences advanced botany, zoology, and mineralogy. In philosophy he was less original and creative than his famous pupil Aquinas. Albertus produced a synthesis of Aristotelianism and Neoplatonism, blending together the philosophies of Aristotle, Avicenna, and Ibn Gabirol and, among Christians, Augustine and Pseudo-Dionysius. Thomas Aquinas
Albertus Magnus’s Dominican confrere and pupil Thomas Aquinas shared his master’s great esteem for the ancient philosophers, especially Aristotle, and also for the more recent Arabic and Jewish thinkers. He welcomed truth wherever he found it and used it for the enrichment of Christian thought. For him reason and faith cannot contradict each other, because they come from the same divine source. In his day, conservative theologians and philosophers regarded Aristotle with suspicion and leaned toward the more traditional Christian Neoplatonism. Aquinas realized that their suspicion was partly due to the fact that Aristotle’s philosophy had been distorted by the Arabic commentators, so he wrote his own commentaries to show the essential soundness of Aristotle’s system and to convince his contemporaries of its value for Christian theology.
The Triumph of St. Thomas Aquinas, fresco by Andrea da Firenze, depicting the saint enthroned between the Doctors of the Old and New Testaments, with personifications of the Virtues, Sciences, and Liberal Arts, c. 1365; in the Spanish Chapel of the church of Santa Maria Novella, Florence.SCALA/Art Resource, New York
Aquinas’s own philosophical views are best expressed in his theological works, especially his Summa theologiae (1265/66–1273; Eng. trans., Summa theologiae) and Summa contra gentiles (1258–64; Summa Against the Gentiles). In these works he clearly distinguished between the domains and methods of philosophy and theology. The philosopher seeks the first causes of things, beginning with data furnished by the senses; the subject of the theologian’s inquiry is God as revealed in sacred scripture. In theology, appeal to authority carries the most weight; in philosophy, it carries the least.
Aquinas found Aristotelianism and, to a lesser extent, Platonism useful instruments for Christian thought and communication; but he transformed and deepened everything he borrowed from them. For example, he adopted Aristotle’s proof of the existence of a primary unmoved mover, but the primary mover at which Aquinas arrived is very different from that of Aristotle; it is in fact the God of Judaism and Christianity. He also adopted Aristotle’s teaching that the soul is the human being’s form and the body his matter, but for Aquinas this does not entail, as it did for the Aristotelians, the denial of the immortality of the soul or the ultimate value of the individual. Aquinas never compromised Christian doctrine by bringing it into line with the current Aristotelianism; rather, he modified and corrected the latter whenever it clashed with Christian belief. The harmony he established between Aristotelianism and Christianity was not forced but achieved by a new understanding of philosophical principles, especially the notion of being, which he conceived as the act of existing (esse). For him, God is pure being, or the act of existing. Creatures participate in being according to their essence; for example, human beings participate in being, or the act of existing, to the extent that their humanity, or essence, permits. The fundamental distinction between God and creatures is that creatures have a real composition of essence and existence, whereas God’s essence is his existence. Averroists
A group of masters in the faculty of arts at Paris welcomed Aristotle’s philosophy and taught it in disregard of its possible opposition to the Christian faith. They wanted to be philosophers, not theologians, and to them this meant following the Aristotelian system. Because Averroës was the recognized commentator on Aristotle, they generally interpreted Aristotle’s thought in an Averroistic way. Hence, in their own day they were known as “Averroists”; today they are often called “Latin Averroists” because they taught in Latin. Their leader, Siger de Brabant (c. 1240–c. 1281), taught as rationally demonstrated certain Aristotelian doctrines that contradicted the faith, such as the eternity of the world and the oneness of the intellect. The Latin Averroists were accused of holding a “double truth”—i.e., of maintaining the existence of two contradictory truths, one commanded by faith, the other taught by reason. Although Siger never proposed philosophical conclusions contrary to faith, other members of this group upheld the right and duty of the philosopher to follow human reason to its natural conclusions, even when they contradicted the truths of faith.
This growing rationalism confirmed the belief of theologians of a traditionalist cast that the pagan and Islamic philosophies would destroy the Christian faith. They attacked these philosophies in treatises such as Errores philosophorum (1270; The Errors of the Philosophers) by Giles of Rome (c. 1243–1316). In 1277 the bishop of Paris condemned 219 propositions based on the new trend toward rationalism and naturalism. These included even some of Aquinas’s Aristotelian doctrines. In the same year, the archbishop of Canterbury made a similar condemnation at Oxford. These reactions to the novel trends in philosophy did not prevent the Averroists from treating philosophical questions apart from religious considerations. Theologians, for their part, were increasingly suspicious of the philosophers and less optimistic about the ultimate reconciliation of philosophy and theology. The late Middle Ages
In the late Middle Ages earlier ways of philosophizing were continued and formalized into distinct schools of thought. In the Dominican order, Thomism, the theological and philosophical system of Thomas Aquinas, was made the official teaching, though the Dominicans did not always adhere to it rigorously. Averroism, cultivated by philosophers such as John of Jandun (c. 1286–1328), remained a significant, though sterile, movement into the Renaissance. In the Franciscan order, John Duns Scotus (c. 1266–1308) and William of Ockham (c. 1285–c. 1347) developed new styles of theology and philosophy that vied with Thomism throughout the late Middle Ages. John Duns Scotus
John Duns Scotus opposed the rationalists’ contention that philosophy is self-sufficient and adequate to satisfy the human desire for knowledge. In fact, he claimed that a pure philosopher, such as Aristotle, could not truly understand the human condition because he was ignorant of the Fall of Man and his need for grace and redemption. Unenlightened by Christian revelation, Aristotle mistook humankind’s present fallen state, in which all knowledge comes through the senses, for its natural condition, in which the object of knowledge would be coextensive with all being, including the being of God. The limitation of Aristotle’s philosophy was apparent to Duns Scotus in the Aristotelian proof of the existence of God as the primary mover of the universe. More adequate than this physical proof, he contended, is his own very intricate metaphysical demonstration of the existence of God as the absolutely primary, unique, and infinite being. He incorporated the Anselmian argument into this demonstration. For Duns Scotus, the notion of infinite being, not that of primary mover or being itself, is humankind’s most perfect concept of God.