What Thomas Aquinas Teaches Us About Apologetics and God’s Existence

by Zach Philip

Does God exist?

To many of us, the answer seems obvious. Of course God exists!

But how do we know?

Thomas Aquinas was a 13th century Catholic philosopher and theologian who had the same question, leading him to an intense study which produced perhaps his most famous work: The Five Ways — five philosophical arguments for the existence of God.

These arguments give us a strong starting point for exploring apologetics (the logical defense of Christianity).

1. Argument from Motion

Dominoes fall. Orange juice spills. A stone tumbles down a hill.

The first domino fell, leading all future dominoes to fall. Your three-year-old sister dropped her cup, spilling orange juice all over the floor. And a gust of wind caused the stone to tumble down the hill.

What the domino, the orange juice, and the stone all have in common is that they have potentials. The domino had the potential to fall, the cup of orange juice had the potential to spill, and the stone had to potential to tumble down the hill.

Motion is what Aquinas calls “the reduction from potentiality to actuality”. It’s not as scary as it sounds.To put that into normal English, motion is the change from wood having the ability (or potential) to burn to it actually catching fire and burning. And the same holds true for the dominoes, orange juice, and the stone.

But nothing can go from just having the potential to it actualizing unless something already actualized causes it to. So whatever is in motion (going from being potential to actual) must be put in motion by something else.

And that means there must have been a “first mover” that isn’t in motion itself: God…


What Thomas Aquinas Teaches Us About Apologetics and God’s Existence