The cosmological argument is an argument for the existence of God based on observation of the world (the effect) from which a conclusion about the cause is drawn. The existence of the world is held to point to the existence of something outside the world, without which the world would not exist. This external factor is what all people understand to be God. Through Aquinas’ arguments, God is shown to be the prime mover, first cause and necessary being, that which depends on nothing.Aquinas’s first way is based upon motion.
Aquinas believed that an object only moved when a force was applied upon it. He then believed that this chain of movements or causes cannot go back to infinity because he believed there had to be a reasonable explanation for the existence of things. Therefore everything in existence is in motion. Aquinas further on mentions in his theory that everything has the potentiality to change for example, babies are born, grow old then die and that this change is caused by something because nothing can be moved on its own thus the unmoved mover, thus there must have been a first mover or a prime mover which in itself was unmoved and quote “motion must be put in motion by another”. Aquinas then argues that the prime mover is God.In his second way based upon the uncased cause, Aquinas argues that cause and effect are natural in the universe.
Therefore whatever event takes place is caused by something else. However infinite regress is impossible because Aquinas already rejected the idea that if a chain or movement went back forever then there would be no reason for the existence of the universe. Therefore, there must have been a first cause which causes everything but itself is uncaused, this is because if something was caused by something else then it is not the first cause, so according to Aquinas it is not possible to say that it is caused itself because then that would conclude that it had previously existed. So overall there must have been a first uncaused causer who is God.
Both the first and second ways are similar because they are both based upon cause and effect. They both begin in a similar structure of beginning with the features of the world that we all already experience, for example in his first way it is the existence of motion and in his second way is the existence of causation. Aquinas explains in both these ways that these features have always existed in the universe, however he argues that there can not be infinite regress of movers or causers. The problem with this is that Aquinas says infinite regress isn’t possible but you end up with an uncaused cause.
He jumps to the conclusion that God is the uncaused cause as he says that things can’t cause themselves but end up into something that is caused itself. Both these ways are different because in the first way Aquinas emphasises what causes the change, and on the other hand he emphasises the effect of the cause.Aquinas’s third way looks at possibility and necessity. There are contingent entities in the world for example; beings which are generated such as humans and nature, therefore something cannot come from nothing because a tree comes from a seed which was planted. Thus there must have always been something since there is something now. Everything is contingent, it could exist but also not exist, therefore there is a possibility there is a time where nothing existed.
However if that were true then there would be nothing here now as contingent entities must have a first cause. Therefore overall, there must have been at least one necessary being, something that has always existed and can be the cause of all other contingent features. This necessary being is God.God for Aquinas seems to be like Aristotle’s final cause of the universe. This is because for Aquinas, God is what started the universe, God who creates and Sustains. He is the maker and the purpose that the world is about God who made the universe with a purpose in mind.
Also because Aquinas was a Christian he naturally believed that the universe was created by God and would not think any other theories about it.
