In the first and second explanations in Aquinas's "Five Ways", Aquinas takes a very logical and simple approach to explaining the existence of God. He reasons that all things are either actuality in motion or potentiality in motion. A body cannot be in a state of potentiality and at the same time, actuality, in the same respect. "Nothing can be reduced from potentiality to actuality, except by something in a state of actuality... it is therefore impossible that in the same respect and in the same way a thing should be both mover and moved, i.e. that it should move itself." This is a seemingly complicated quote that, when broken down, really sums up what Aquinas is trying to say in this whole "potentiality" and "actuality" thing. He uses the example of heat. The fire is actually hot; it is in a state of actuality. In order for wood, which is potentially hot, to reach the state of actuality, i.e.,
being hot, the fire must act upon it. It is not possible for the wood to spontaneously become hot, putting it at an actualized state. His first premise is that the chain of things in actuality cannot go back infinitely. Nothing can move itself, and therefore, there must be a first "unmoved mover", God. This is largely based on his studies of Aristotle, who argued that planetary motion, which caused the change of seasons, must have an "unmoved mover", to keep order.
This view only differs slightly from the "NaÃÂïve Version". In the naÃÂïve version, all events are much like a line of dominos. The last one falls as a result of the one before it falling, and so on. The person who initially tips the first domino is God in this example. There cannot be an infinite line of...