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The Five Ways of St. Thomas Aquinas, Part II

July 12, AD2017 0 Comments

Last month I presented the First Way St. Thomas Aquinas explained the logical existence of God. Here is the Second Way. While this is a quick read, it may take some effort to discern St. Thomas’ subtle concepts because of the different use of words between his time and ours.

The Second Way: The Argument from Efficient Cause

The Second Way is about causes of being or existence. “In the world of sense,” St. Thomas states, “we find there is an order of efficient causes. There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible.”

An efficient cause is “that which brings something else into being.” St. Thomas builds his argument from Aristotle’s Four Causes, which states that the agent is that which brings about the change. An efficient cause could be an artist changing a block of marble into a sculpture, or a carpenter changing pieces of wood into a table. A bonfire does not need a cause to be hot, but it does need a cause to be a bonfire.

“Nothing that is brought into being can be its own efficient cause.” Nothing causes itself to come into existence. As with the First Way, without a first efficient cause, there can’t be a second and subsequent efficient causes. Logic tells us that there must be a first Efficient Cause that is uncaused; that which brings all other things into being is in itself Pure Being.

Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God.

We Catholics state this belief every time we pray the Glory Be, proclaiming our belief in God Who is, always was, always will be. God is not the result of any other cause. Catholics see this evidenced in Genesis 1: 1-31 & 2:1-9. In Exodus 3:14, God gives His name as “I AM WHO AM,” or Pure Being.

If you’re up to reading the original as Aquinas wrote it, you can find it at

Next: Part III: The Third Way of St. Thomas Aquinas

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About the Author:

Michele is retired, happily married, the mother of two adult daughters and has one granddaughter. As a lifelong Catholic and writer, she has managed to find a way to write in most of her career positions. She spent 35 years as a registered respiratory therapist, during which time she was given opportunities to write for the hospitals where she worked. She earned her Certificate in Healthcare Quality in 1994, which led to more writing opportunities. Some of this writing included grant proposals, educational materials, brochures, patient home care materials, policies and procedures. Later, she wrote articles and blogs for websites on legal, medical, genealogy, and RVing/camping topics. Noting that Truth, Jesus, and God have been increasingly disregarded, she hoped for an opportunity to write about the Church, Truth, and the wonderful things she's learned, with God's guidance, from a Catholic point of view.

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