3. If something exists there must exist an independent thing.
This is established from my argument for premise 2.
4. Something exists.
Here’s betting somebody will challenge this.
Therefore an independent thing exists.
Yes, indeed. To keep Sir William of Ockham happy I think it would be best to limit the number of these independent things to 1. While there is nothing stopping more of them existing 1 is logically enough.
Next I will contend that this independent thing is God. I’ll bet you can’t wait.