Proof Through Causality and Necessity

We're covering St. Thomas Aquinas's 5 proofs for the existence of God. Here's the second: Causality.

Our parents caused us to be born. Our grandparents made the decision that created our parents, and so on and so on. So every cause was itself an effect of a previous cause. So, in order to go back to a true "beginning," you'd have to find the cause of all causes. Just as the force that started the motion from potential existence to actual could not have been potential, itself, the cause of all causes could never have been an effect from a previous cause. In other words, the cause of all causes was never an effect, but what philosophers call an uncaused cause. St. Thomas argued that uncaused cause is God. He caused everything by creating it in the first place.

Here's the third proof: Necessity.

If you had never been born, the universe would not have been affected. No one person is necessary to the universe; everything is dependent on something else in order to exist. One example of this idea is the relationship between electricity and lightbulbs. Once a switch is turned off, the flow of electricity is cut off. No electricity, no light. In the same way, if God removed his Being from sustaining us, we'd all be like turned-off bulbs. One being must be necessary to keep the unnecessary ones in existence. Otherwise, nothing would exist at all. St. Thomas said this necessary being is God.