Thomas Aquinas (1224–1274) was an Italian theologian and philosopher. He is often regarded as the greatest theologian of the Middle Ages.

Aquinas was a Dominican monk who eventually became a professor at the University of Paris. In his student days he carried the title of “dumb ox.” Later in life he became more affectionately known as the “angelic doctor.” His most significant work was his Summa Theologica which consisted of over 1.5 million words.

Aquinas held a high view of philosophy and was greatly influenced by the philosopher, Aristotle. Aquinas’s contributions to philosophy are fourfold.

First, Aquinas merged Christian theology with the teachings of Aristotle. For most of church history, whenever the church looked to the ideas of a particular philosopher, it looked to the teachings of Plato. In the thirteenth century, though, there was a rediscovery of the teachings of Aristotle. Although not the first person of his century to use Aristotle, Aquinas relied upon Aristotelian concepts when formulating his own theology. For example, Aquinas’s view of the Eucharist closely parallels Aristotle’s theory of categories in which “substance” is the primary reality of a thing while all other categories such as quality, time, and state are dependent upon the substance. For Aquinas, the substance of the Eucharist was the actual body of Jesus Christ even though the appearance of the Eucharist was that of literal bread.

Second, Aquinas offered five proofs for God’s existence which upon review can be distilled into two main arguments—the cosmological and teleological. The cosmological argument asserts that all existing and contingent things like the earth rely upon some uncaused non-contingent being for their existence. For Aquinas, the earth came into existence by the Christian God who himself does not have a cause. (Aquinas’s cosmological argument parallels Aristotle’s concept of the “Unmoved Mover” who started all things in motion.) The teleological argument, which Aquinas also used, asserts that the incredible complexity in the universe points to an intelligent being who created it all.

Third, Aquinas argued that there was a close connection between faith and reason. For most of its history, the church viewed faith as superior to reason and saw no need to justify the truths of Christianity by the use of reason. Aquinas, though, viewed faith and reason as working closely together. In fact, he believed reason could be used to justify many elements of the Christian faith. Unlike some theologians before and after him, Aquinas felt that Christianity need not fear reason. When used correctly it affirmed what God had revealed in Scripture.

Michael J. Vlach, Ph.D.