You need to consult a dictionary to find out what the word "proof" means. A proof is not an assertion which has zero evidence to suppose it is true, and has zero reasons to suppose it is true. To assert something as being definitely true but without any reason or any evidence to support their assertion is, quite frankly, rank stupidity.
Hmmmm, proof , proof..ah here we go!
From dictionary.com:
"proof:
The evidence or argument that compels the mind to accept an assertion as true.
The validation of a proposition by application of specified rules, as of induction or deduction, to assumptions, axioms, and sequentially derived conclusions.
A statement or argument used in such a validation.
Convincing or persuasive demonstration: was asked for proof of his identity; an employment history that was proof of her dependability.
The state of being convinced or persuaded by consideration of evidence.
Determination of the quality of something by testing; trial: put one's beliefs to the proof. "
Since there is noone asserting or belivieving that a Narnia type world exist why would Dawkins have to go through the trouble of supporting his assertion? If someone came up with an objection I'm sure Dawkins might oblige. How about taking him to task personnaly? Otherwise you'll have to deal with the peanut gallery.
If the existence of a Narnia type world is of extremely low probability, then this is an assertion which simply must be justified. Otherwise why should myself or anyone else believe you?? People can pull as many assertions from their backsides as they like, but if they are wholly lacking any evidence and/or reasons to support their assertions, then it's just that i.e their backsides talking.
I believe that some here have been giving you arguments as to why a Narnia type world is improbable.
Well yeah. So a 17th century Dawkins would have asserted mobile (cell) phones do not and cannot exist, meteorites cannot and do not exist, heavier than air flight cannot and never will exist, human beings travelling faster than 30mph cannot and never will exist.
Well, for a 17th century Dawkins a cell phone would not exist, and since he would be long dead today, would never exist for him. (considereing that he would know what a cell phone was in the first place) Cell phones exist because someone born well after the 17th century invented a cell phone. If the cell phone was never invented the cell phone would never exist.
All those people were justified in thier claims because they were limited to what they knew. Time and discovery bore them out to be wrong. Just like today, we believe that man will never go faster than the speed of light because of what we understand about TLOP right now. We may achieve it, we may not. That is for future history to determin. But right now I can say the we will never go faster than the speed of light because everything we know tells us that we can't. I can be justified in saying that untill the day we actually do achieve FTL travel. Of course at that point the necessary understanding which would allow us to achieve FTL travel would be making itself evident and support for my assertion would be waning. Someone can't say with assurity that we will go faster than the speed of light because that only remains a possibility at this point. He can only be proven right when we actually do go FTL.