Aquinas drew a distinction between theology and philosophy; to him, philosophy was drawing conclusions based on distinctions in the natural world whereas theology was the same albeit with the supernatural. Aquinas differentiated both by calling recourse to the “Domain of Faith” and the “Domain of Reason” of which both overlapped and diverged in different ways. However, Aquinas is adamant that the two domains can never come into conflict.
This approach derives from Aquinas’s theory of knowledge. This is something he takes from Aristotle. So, to quickly sum up Aristotle’s theory of knowledge…
The key claim relevant is that Aristotle believed all knowledge originated in sensation. This is unlike in Platonism where one can have a vision of the Forms independent of sensible things; Aristotelians, on the other hand, everything we know must somehow be based on the senses. The senses provide the reasoning by means which reason can then work and mold. Essentially, this means that we can come to know something based off of our experience of sensible things—example, we come to know “fire” based off of its hotness and how it can cook our food but also scorch our skin. This would hold true for all things, supposedly.
Aquinas only slightly modifies this claim. To Aquinas, it is true only of natural knowledge and of our present life; God can reveal to us supernaturally what cannot be inferred from sensible experience. In the next life, then, God will raise our faculties so as to be capable of seeing him. From this, Aquinas draws some conclusions: (1) sensible objects are effects of God, they give us evidence of our creature; simply by using our reason, then, we are able to draw out some understanding of God; (2) However, some things are inaccessible to us and so must be revealed by God. Therefore, the natural world which we can come to know is what Aquinas calls “Preambles to Faith”. These preambles include the following caveats about God: that God exists, that there is only one God, he is omnipotent and immutable and so forth. In principle, we can come to know these truths based from our reasoning about sensible things; then, (3) sees Aquinas talking about “Mysteries of Faith”, those things which cannot be known to us except by divine revelation. This brings us the idea of why truths which surpass human knowledge even exist. For instance, why would Aquinas believe that there is supernatural truths, why couldn’t those naturally revealed truths be all there is? Aquinas gives several arguments but professor Williams remarks that the best argument is probably taken from the defects of our everyday knowledge. He remarks that our senses are best set-up to know this life. Everything which is beyond the sensible requires us to reason very carefully and we are still liable to make mistakes. But, even when it comes to sensible objects, we cannot fully discover their natures. Ergo, if we cannot even grasp fully the nature of a tree, then why would we believe we could grasp the nature of God? Therefore, for an Aristotelian, there should be truths that even we struggle to know based on our natural powers.
If we accept this, then we must ask ourselves why our own reasoning isn’t enough. Why is Aristotelian philosophy, those “preambles to faith” inadequate? God’s revelations are important for several reasons: for one thing, human beings have both a natural and supernatural destiny, this destiny cannot be figure by reason alone and attempts to figure as much is what Aquinas calls “Reasons of Error”. So, this supernatural destiny curbs our natural reasoning, making us submissive to God. Secondly, though, revealing these mysteries is a generous act on God’s part; we enjoy divine revelations more than our own reasoning. But, this brings us to another issue: is it not foolish and irrational to believe in things beyond reason? Not to Aquinas who argues that God confirms the truth of the supernatural teaching by “works which surpass all nature”. Meaning, miracles. Accordingly, it is not irrational to believe in these truths beyond normal reason because God confirms these natural truths by his demonstration of supernatural power.
Aquinas goes on to speak of how it is necessary for God to reveal these truths because most people simply are not able to mentally compute these truths. For lack of a better word, humanity is “stupid” and cannot naturally understand these truths. Others, meanwhile, are either too lazy or too busy. Young people cannot know them since they are too distracted by their hormones. Such truths, then, are the pinnacle of knowledge, not its foundation. As such, if God did not reveal the preambles, no one under the age of forty would even know that God exists.
But does this mean that philosophical truths and theological truths conflict? Not to Aquinas.
Nature, to Aquinas, is something given to us by God. Just the same, faith, based on revelation, is a gift from God. So, there may be two ways to that truth, but it all comes from God. Either way, though, it is god and God cannot contradict God. All truths, after all, are contained within divine Wisdom and divine wisdom cannot contain contradiction; said again, God teaches us through both natural and divine means and so to contradict those teaching would make him a bad teacher, a contradiction. Truth cannot be opposed to truth. Ergo, there cannot be a conflict, only an appearance of conflict, that reason itself is not useless by itself—a holding of the Augustinian tradition—and has value insofar as it is a tool in itself to come to know God’s creation.
Our job, then, is finding the mistake. Interpretation and re-interpretation, then, becomes central.