A: You’ll hear Theists say that the reason why the all physical things exist is because God caused them. But this just leaves us with the problem of who caused God, and so such an argument solves nothing.
B: That shows a fundamental misunderstanding. The sorts of arguments you are talking about conclude to God as an uncaused cause. He simply is existence, not existence from another.
A: So you are saying that these arguments say that God exists by definition?
B: Yes, that’s exactly right.
A: But there is no such thing. There is no definition that has existence in it. I thought I was being charitable by not basing the argument on the impossible, but merely saying it was insufficient. Why base the argument on an impossible or unknowable thing?
B: Well, it’s what God’s definition would be, if we could know it.
A: That’s just as bad – a definition that you can’t know? That is simply unknowable?
B: The definition isn’t an axiom – it’s a conclusion that we come to by considering causality. In a series of causes, there must be some cause that isn’t an effect. But every cause causes existence, so there must be some cause that does not have caused existence. Again, if every existence is caused, then there would be nothing to cause it.
A: Let’s say arguments like this work. What’s keeping me from applying modus tollens to them and simply saying “if all these arguments are true, then there is some essence that is the same as his existence. But this is unintelligible. Therefore these arguments are not true.”
B: My things are prior and better known, and to lose them is to lose even the possibility of modus tollens. Let me try to explain that later.