Sunday, March 21, 2010

Aquinas Five Proofs

At various time like all humans, in our group,  we have wondered what God is, and indeed, probably most of us would admit we at times wonder if a God does exist. Is God a single being, a ground of being, or some force of quantum physics. As a possible answer to this age old question, one of our members provided this written version of Aquinas five proofs for the existence of God, as printed online at the website for John Carroll University in Cleveland.


Sir Thomas Aquinas was one of the greatest medieval philosophers. He tried to show the harmony between faith and reason, and between Christianity and philosophyt. Aquinas's views have been very influential, especially in Catholic thought.

Aquinas gave five classic "proofs" for the existence of God. These are on a class handout, which in turn is taken from his massive Summa Theologica (Part 1, Question 2, Article 3). These computerized exercise materials are copyrighted (c) 2002 by Harry J. Gensler of the philosophy dept at John Carroll University but they may be distributed freely.

Aquinas's Proof 1 to 3

1.  FIRST MOVER: Some things are in motion, anything moved is moved by another, and there can't be an infinite series of movers. So there must be a first mover (a mover that isn't itself moved by another). This is God.

2.  FIRST CAUSE: Some things are caused, anything caused is caused by another, and there can't be an infinite series of causes. So there must be a first cause (a cause that isn't itself caused by another). This is God.

3.  NECESSARY BEING:  Every contingent being at some time fails to exist. So if everything were contingent, then at some time there would have been nothing -- and so there would be nothing now -- which is clearly false. So not everything is contingent. So there is a necessary being. This is God.

Aquinas's Proofs 4 and 5

4.  GREATEST BEING: Some things are greater than others. Whatever is great to any degree gets its greatness from that which is the greatest. So there is a greatest being, which is the source of all greatness. This is God.

5.  INTELLIGENT DESIGN:  Many things in the world that lack intelligence act for an end. Whatever acts for an end must be directed by an intelligent being. So the world must have an intelligent designer. This is God.

Web Resources

Click below to read Aquinas's writings:


Click below to read an article about Aquinas:


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