If an elderly but distinguished scientist says that something is possible he is almost certainly right, but if he says that it is impossible he is very probably wrong.
Arthur C. Clarke
When, however, the lay public rallies around an idea that is denounced by distinguished but elderly scientists and supports that idea with great fervor and emotion — the distinguished but elderly scientists are then, after all, probably right.
Isaac Asimov
(reblogged from Futility Closet)
Digital, Data & Policy 
And absence of evidence isn’t evidence of absence.
Yes, indeed.
Can we add generality to statements like this, but keeping in the spirit of the original?
For example, there’s an old joke about scientists seeing thirty white sheep and ten black sheep in a field:
One says, “A quarter of sheep around here are black.”
The next says, “A quarter of the sheep in that field are black.”
The third says, “A quarter of the sheep in that field are black on one side!”
But in keeping with the spirit of Arthur C. Clarke’s statement, how might one add generality?
How about, “If someone says that something is possible he is almost certainly right, but if he says that it is impossible he is very probably wrong.”