Can a lack of evidence be considered proof?

[robvalue]

I would say that absence of evidence is evidence of absence; but how strong that evidence is depends on the individual case. It's certainly a factor to consider. But it's not necessarily sufficient evidence, or even strong evidence, which is what I think people generally mean by the rule of thumb.

I think absence of evidence could be considered proof if a statement is very specific:

"I have a [regular] baseball in my right hand."

I look in the person's hand. They have no baseball in it.

I'd say I've proved that claim false via lack of evidence. I suppose you could say I have positive evidence that they don't have it in their hand, because if they did, I'd be able to see it. To state otherwise is to refer to the limits of my senses and such and retreat into solipsism. Which you can do, if you want.