Written by Jason Petersen
Thomas Aquinas was the one who developed this argument. This argument is not as well known as the Kalam Cosmological Argument. The argument begins with the observation that this universe has objects that are within motion, but it argues that in order for the universe to be in motion there must of been caused by a prime mover.(God.)
Let’s take a look at the premises for this argument:
P1. There are objects that are in motion.
P2. If an object is in motion, then its motion must be caused by something outside of itself.
P3. There cannot be an infinite regression of movers.
P4. So, there must be an unmoved mover who set everything in motion.
Conclusion: The unmoved mover must be God.
This argument is very similar to the Kalam Cosmological Argument in which it implies you can’t have an infinite number of past events. Thomas Aquinas argues that if an object is set into motion it is caused to go into motion by something outside of itself. However, if we were to take God out of the equation then that would entail an infinite number of past events because when something goes into motion it is caused by something else. For instance, planets, asteroids, stars, asteroids, were put into motion by something else.
Only something that would be outside of the universe would be able to put the universe into motion. God is the only possibility that fits the required description to put the universe into motion because God’s properties entail that he has no beginning or end. Therefore, God exists.