Here's an interesting post I came across on another site.
...But not all propositions are created equal. It is indeed true that some cannot really be disproven - for example, the claim "a black swan exists" cannot be disproven. To do so would require examining every spot in the universe to make sure that such a swan did not exist, and that simply isn't possible... Â
Source: http://boards.historychannel.com/thread....4352105000
I have searched every spot in the universe for you (well, Adelaide, actually) and here is a Black Swan.

My family and I have fed flocks of them on the River Torrens.
Now, let's see if I can find a picture of God as easily.
If I said I found God in Adelaide, that presumably would not be as good a proof as the assertion that there are Black Swans aplenty there?