Atheism and the existence of peanut butter

[R00tKiT]

The cosmological argument might be persuasive as a first cause argument ([*note 1]), but it is a non-starter as an argument for the existence of any god.  

Well, I think it's already progress enough if we manage to agree on the existence of a first cause based on this argument. Arguing for a god requires additional arguments, of course.

This is easily shown by the following facts.  The cosmological argument requires that this universe be caused, but it does not require that the cause be supernatural. 

Well, when you think about it, this cause must be supernatural. If by natural you mean anything inside the universe, then a cause of the universe has to be outside of it, and because it caused the natural world, it can rightfully be labeled super-natural, or if you don't like the term, simply non-natural.

 In order for any cause to be a god, it must be supernatural because a natural cause is not a god. 

As I explained above, a cause of the natural world can't also be natural. Nature is simply the label we assign to what's around us. So, any cause of the universe, even if it's not a deity, can't be called natural.

But if the cause of this universe lies within another, natural universe, we have no way of knowing if that universe began to exist, nor what the laws of that universe even are.  So the cosmological argument gets us one step back and then fails miserably to demonstrate the minimum needed to demonstrate a god, that the cause is supernatural.  Furthermore, there can be no evidence that the immediate cause of this universe is supernatural, as the supernatural is defined as any non-natural cause, and to demonstrate a non-natural cause, you must show that no natural cause can be the source of the effect.  There is no argument that can show there is non-natural cause beyond arguments from ignorance, which are invalid.

Again, you really have to define the word natural. If other universes exist prior to this one, then it's not really a defeater. We can simply consider them all together and call them a collection of universes. This entire collection can then be a premise of the same argument.

So, summing up:

1. The cosmological argument does not demonstrate a supernatural immediate cause of the universe;
   
2. No argument can demonstrate that the immediate cause of the universe is supernatural;
   
3. If the immediate cause of this universe is natural, then the premises of the cosmological argument may be violated by that prior cause;
   
4. Therefore, the cosmological argument cannot demonstrate that an immediate cause of this universe needed a cause;
   
5. Therefore, the cosmological argument cannot demonstrate that an ultimate, supernatural cause of this universe is necessary;
   
6. Therefore, the cosmological argument cannot show that a god is necessary for the existence of this universe;
   

All these shortcomings, assuming they are true, can be circumvented by adjusting the definition of the universe without changing the argument, as I did above.

1. Corollary, no a posteriori argument can show the existence of a god given the above,
      for example, the universe may have been designed by natural intelligences in another universe;
   

Your corollary is simply false, the teleological argument is also considered to be an a posteriori argument, which you didn't address. And all your objections to the cosmological argument are either moving the goalposts or minutiae about nomenclature.