Disclaimer: These posts assume the view that the Big Bang was the actual beginning of all time, matter and space. This is just one view of many in cosmology.
I am going to try to finish up this series of thoughts on the Kalam Cosmological Argument in the next couple of weeks. Here is the argument in its most common form today, as promoted by William Lane Craig and others.
1. Whatever begins to exist has a cause.
2. The universe began to exist.
3. Therefore, the universe has a cause.
This short post will focus on the argument's circular nature. The first premise uses the phrase "Whatever begins to exist". Yet anything and everything that has ever begun to exist (that we know of) is part of the universe. So "whatever begins to exist" is equal to "the universe." So we could reformulate the argument this way:
1. The universe has a cause.
2. The universe is the universe.
3. Therefore the universe has a cause.
or you could do it this way:
1. Whatever begins to exist has a cause
2. Whatever begins to exist begins to exist.
3. Therefore whatever begins to exist has a cause.
"Whatever begins to exist" and "the universe" are only distinguishable from each other if one assumes a perspective from outside the universe, which is what the KCA is trying to prove. So you have to assume it to be true for it to possibly be true.
We could also recall the ideas from posts one and three about causes. Since everything existing in the universe now did not pop up out of nowhere, but is rather a reorganization of materials that have always been here, then nothing has ever truly begun to exist except the universe. So once again - "Whatever begins to exist" = "the universe", and the KCA does not offer a useful philosophical proof.