As I said in my last post, I am doing work on the life and theology of Thomas Aquinas for a history class I’m taking. I wanted to take excerpts from a paper I’m writing, and develop them for the ole’ blog. In these next two posts I’m going to consider Thomas’ theological and philosophical contributions to the church. In this post, I want to look at what is known as the “two-truth theory”, and how Aquinas helped save the place of secular philosophy in the Christian university.
As I said in my last post, during Thomas’ years as a teacher in Paris, he was involved in a controversy with a group of Aristotelians called the Averroists. Averroist philosophers espoused what is commonly called the “two-truth theory”.
McInerny explains what this theory means:
[The Averroists] were masters in the faculty of arts to whom the infamous “two truth” theory is attributed. That is, what they seemed to be saying is that something can be true in philosophy and false in theology, and vice versa. As Aristotelians, as philosophers, they accepted the cogency of positions which were in conflict with their presumed Christian beliefs… The eternality of the world is a philosophical truth, its non-eternality is a truth of faith.
The Averroists believed that the two disciplines of philosophy and theology could be in contradiction to one another. It can be philosophically true that the universe is eternal, while being theologically true that the universe is created by God. Beyond this teaching, the Averroists taught Aristotle erroneously. They misread and misinterpreted several of his works, which is why they were considered to be heterodox in their teaching.
Thomas, who was himself an Aristotelian, had been lumped into the Averroist group by his opponents, which forced him to write a response to the Averroists. Thomas’ response was both important and timely, especially considering the fact that the university in Paris was already apprehensive to pagan philosophy — this only exacerbated the problem.
Thomas replied by arguing that the two-truth theory violated the “fundamental law of thinking, the principle of contradiction, -(p. – p)”. In other words, the universe is either eternal or it is not. It cannot be both. By making this argument, Thomas contended that philosophy and theology did not contradict one another. Rather, they fit together.
In addition to that, Thomas also made another important argument, namely that Aristotle taught only what his human mind could understand unaided by divine revelation. In making this argument, Thomas made an important distinction between philosophy and theology: philosophy is the study of what can be observed by the natural senses, unaided by grace; theology, on the other hand, is the study of what is supernaturally revealed by God. Both are legitimate sciences, and should never contradict; but they are not the same.
McInerny explains, saying:
Revelation is over and above what man’s natural endowments can attain; Aristotle thus becomes the privileged representative of what man can know using only his natural powers. A truism of the relation between the two orders is that the supernatural presupposes and does not destroy the natural”.
It was an assumption during Thomas’ time (and is still today!) that divine revelation can and does contradict the secular sciences. Moreover, it was feared that by using philosophy, one would be led astray into paganism. However, what Aquinas argued was that they go together, like a hand in a glove. Aristotle, through natural observation, discovered many important truths; however he could only go so far without the aid of divine revelation.
Taylor Marshal explains this point further:
For Thomas, philosophy was the “handmaiden” of theology. This means that the power of reason and the truths known through reason are able to aid and assist men in theology. The key to understanding Thomas Aquinas is seeing philosophy and theology as distinct but not unrelated. For example, Thomas holds that a pagan person living on an island in the middle of nowhere can know the truth that God exists…[However,] Thomas also holds that there are truths that can never be known by reason alone. It is revealed truth. [For instance], he grants that the Trinity cannot be known by reason alone…
So theology and philosophy are complementary, yet distinct. Looking at biblical texts like Romans 1, this makes complete sense. Anyone can look at creation, and understand that God exists. Yet it is impossible to understand the hypostatic union without special revelation.
It was based on these principles that Thomas attempted to synthesize much of Aristotle with Christian theology. He truly believed that philosophy, when done rightly, was not in contradiction to theology; that it was not to be pitted against divine revelation. Rather, when placed together rightly, they would compliment one another. Because both the secular and sacred, both philosophy and theology, ultimately come from God!
“The heavens declare the glory of God!” (Psalm 19:1)
 Ralph McInerny, Aquinas, 21
 Ibid, 32