Aquinas goes on to attempt to further strengthen his Cosmological Argument in his Third Way: The Argument from Contingency.
In this way, Aquinas argues that all things which exist in nature are contingent; they did not exist, in the future will cease to exist and, as well as this, it is possible for them never to have come into existence.
While it may indeed be true that everything in the universe does have a cause, it does not necessarily mean that the universe itself has a cause; the fact that everything which humans can observe can be explained by a precedent cause, this doesn’t mean that the universe can be explained in the same way.
The atheistic philosopher Betrand Russell agrees with this point and claims that while all humans have mothers, ‘Obviously, the human race hasn’t a mother, that’s a different logical sphere’ in his book Why I Am Not a Christian.
For example, though it may be possible to imagine a magician pulling a rabbit out of a magician’s hat without having a cause of its existence, this does not mean that it is logical to think that it is possible.
By this logic, while it is possible imagining the universe coming into existence without a cause, that does not mean that it is logical or reasonable to think so.
He argued that we make assumptions about the relationship between Cause and Effect which are by no means necessarily true.
While it is true that, according to human logic, infinite regression does not seem logical, in mathematics, it is possible to have an infinite series of regression; numbers can keep increasing or decreasing in size infinitely, thereby proving that infinite regression is entirely possible.
Once again, because Aquinas rejects the possibility of infinite regression, this means that ‘it is necessary to admit a first efficient cause to which everyone gives the name of God.’ Both of these two ways are heavily influenced by Aristotle’s idea of a prime mover.
However, Aquinas does not mean to argue that God is merely the being that started off the chain of events which lead to cause the universe and everything in it.