Why Philosophy Isn’t Enough, According to St. Thomas Aquinas

By pintswaquinas April 12, 2023

Philosophy helps us uncover some of the deepest truths of existence. The Church even teaches that we can know the existence of God and obtain limited knowledge of some of His attributes from reason alone.

Why, then, do we need theology? After all, knowledge of God is the highest knowledge of all. If philosophy affords us a glimpse into God’s nature, what can theology offer?

St. Thomas Aquinas was a philosopher, but in his “Summa Theologiae,” he argued that theology (knowledge of God based on divine revelation) was still necessary.

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Here’s why.

Theology reveals truths that our reason could not discover.
Isaiah 64:4 says, “The eye hath not seen, O God, besides Thee, what things Thou hast prepared for them that wait for Thee.”

We are directed to a goal — communion with God — that we cannot grasp intellectually. And many truths about God can’t be discovered by reason alone, such as the Trinity and the Real Presence of Christ in the Eucharist. God reveals these truths that exceed our reason so that we can arrive at the supernatural goal He calls us to.

Theology aids us in knowing even truths that we could discover by reason.
St. Thomas says, “Even as regards those truths about God which human reason could have discovered, it was necessary that man should be taught by a divine revelation.”

We acknowledged that certain things about God — such as His existence — can be discovered by reason. But Original Sin darkened our intellect and weakened our will, so these truths are not always obvious to us. Revelation is the light shining in the darkness to show us what our clouded minds have trouble perceiving.

If we didn’t have divine revelation, St. Thomas says, the knowledge of God attainable by reason “would only be known by a few, and that after a long time, and with the admixture of many errors.”

We see this in other religions that don’t enjoy the divine revelation we have in Scripture and Sacred Tradition. Although there are elements of light and truth, they’re mixed with many errors. This shows how difficult it is to come to an accurate knowledge of God without divine revelation.

It’s important to note that revelation doesn’t interrupt or contradict reason. It raises it beyond its normal capacity. Ultimately, philosophical truths can never be in disagreement with theological truths. If there’s a contradiction, you’re doing your philosophy or your theology wrong.

We are beings called to a supernatural end surpassing our reason. Thankfully, God hasn’t left us in the darkness. We have philosophy to get us started on the right path, but revelation is what will get us to our destination.


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