Proof for Aquinas is a rational demonstration that is fundamentally founded upon sense observation but which may become more abstract depending on what is being discussed. Before Aquinas presents his five proofs for the existence of God in the Summa Theologica, he writes about the kinds of demonstrations that can be made according to the ideas of cause and effect. One kind of demonstration proceeds from cause to effect and another kind proceeds from effect to cause. Aquinas’ five proofs for the existence of God are demonstrations from effect to cause because God as the first cause of things and the world around us is not self-evident or known to us as we know and see the things in the world he has made.
