Hi forgiven,
Just a note on what might be the problem here (I could be wrong). It appears you have constructed an unsound argument. Consider the following:
1. All dogs have fleas.
2. Rover has fleas.
3. Therefore Rover is a dog.
The above is quite obviously unsound because premise one is false - not all dogs have fleas. The same applies to your syllogism: P1: "That which begins to exist has a cause" is false - you are assuming the consequent. The premise has NOT been shown to be true in all cases. Therefore your question is invalid. Hope that clarifies things.
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