The Cosmological Argument for the Existence of God (as presented by St Thomas Aquinas)
Created | Updated May 26, 2004
The question as to how the universe came to be, and why it is the way it is has been pondered for centuries. The basis of many religions is that there is a creator God who is responsible for the Universe, and is therefore the answer to these questions. Many philosophers, from Socrates to Swinburne have therefore debated God’s existence, and three classic arguments for why God must exist have been formed.
The Christian scholar St Thomas Aquinas presented five arguments for God’s existence, which have become known as the five ways, in his Summa Theologica1. The fourth way deals with the need for God as perfection whilst the fifth way states another of the classic arguments for the existence of God, the Teleological argument. Of concern here however, are the first three ways, which comprise the Cosmological argument.
The First and Second Ways
The First Way, which Aquinas thought was the strongest, is the argument from motion. This argues that if an object has the potential for motion (for example a billiard ball which is not stuck to the table) then it can experience motion or change, be it of a spatial, temporal, or qualitative nature. He argues that something cannot put itself into motion, and can only be put into motion by another object which is already in motion (e.g. another billiard ball moving towards it). Therefore, every object in motion was caused to be in motion by another object, which was itself in motion. Aquinas did not believe that an infinite regress was possible, since if this sequence of movements was infinite, then there was no beginning, and he regarded this as being unintelligible, since if there was no beginning, then there could not have been motion. Since to Aquinas, the universe was intelligible, therefore there had to be a beginning, which necessitated a primary mover who was able to move themselves, an ‘unmoved mover’. Aquinas postulated that this was God. The Second Way is a similar argument, though it deals with causality, seeing God as the ‘uncaused causer’.The Third Way
This is the argument for necessary and contingent beings. For Aquinas, existence was comprised of beings. The world consisted of contingent beings which had a finite existence, which would be generated and which would perish. Following on from the first two ways, Aquinas pointed out that all contingent beings have a prior cause. If all beings were contingent, then it stood to reason that there would have been a time prior to the generation of the first contingent being when nothing existed. If there were no contingent beings around, then nothing could have caused the first contingent being, so nothing could have existed. Since contingent beings do exist, it is therefore necessary for there to have been a non-contingent being, a ‘necessary being’ which Aquinas identifies as God.These three ways therefore make up Aquinas’
version of the cosmological argument for the existence of God.
See also:
Criticisms of Aquinas' Cosmological Argument
The Cosmological Argument in the Kalam Tradition
1Part 1, Question 2, Article 3.
