Actually, all of the important arguments for the existence of God are logically valid, or at least have a plausible case to be so, which is the about the most that can be said for the Kalam Cosmological Argument. If they didn't, nobody would give them the time of day. The usual reason such arguments fail to 'prove' anything is that their premises can be plausibly rejected, and that includes the KCA again.
Sorry, I was mixing my terms, you're right in that the structure and (usually) reasoning used is valid but the premises are often vague or unfounded, which is pretty much what I meant but I wasn't expressing myself very well. I'll try to be good in future.
Zafran said:
Like the Kalam Cosmological argumnet - that relies on finite past.
The cosmological argument is pretty weak, and it's not just about me rejecting something I don't like, it's flawed in a few pretty big ways.
The argument usually takes the form:
1 Whatever begins to exist, has a cause of its existence.
2 The universe began to exist.
3 Therefore, the universe has a cause of its existence (and that cause is God).
Cause and effect don't always work in the tidy way that seems intuitive. e.g. In radioactive decay, one cannot determine when or why a particular particle will decay, only that it will decay in a certain time with a given probability. There is no classical "snooker ball" cause and effect, particularly at the quantum level.
If we are to say Y has a cause, what we mean is X is the cause of Y and X precedes Y in time. As far as we know, time did not exist before the universe so to say that something can cause it makes no sense if we understand that the cause must happen
before the effect.
Also there's the obvious jump at the end.
The universe must have a cause, therefore that cause must be God. Why must it be God, and is there any reason to think that such a thing is even plausible?