Heisenberg's uncertainty principle would be another example of a "negative proof" - the better you know the position of an object, the less you know its momentum, until at the ultimate point you know all about one and nothing about the other.
Hank Kerchief has pointed out that the way get a believer to understand disbelief is through appropriate use of definitions. My reply was that if the definition is nebulous enough, ala Deists' ideas about God, the definitional approach might not work.
I don't think this is really what it means to say one cannot prove a negative, which almost always pertains to an existent. The fact that one cannot determine the exact position of something depends on it actually existing.
Hank
Yes, you said: " It seems, though, that your argument is vulnerable to a nebulous definition - for instance, that God created the universe. The Deists believed that God's "testament" was in His works, which we see all around us."
That is my very point. The Deists do not define God, they simply use the word and it amounts to nothing more than "whatever came before everything else." As soon as someone attempts to assign actual attributes to it, it becomes testable and probably disproveable. In the mean time, to believe in something on the basis of a "word" without definition is identical to my Morkano, which exists and no one can prove it doesn't, because it has no definition.
Absurd? Just because I used the spelling Morkano instead of God?
Hank