Comment by nerdponx

As with all things in life, it's a matter of accumulating evidence up to an acceptance criterion. That criterion can never be 100% certainty, because nothing can be 100% certain.

The difficulty lies in agreeing on what that point should be, and on the magnitude of any particular piece of information as evidence for or against any particular hypothesis.

"The fence was a mistake" is a completely legitimate conclusion here. The principle exists to prevent us from jumping immediately to that conclusion out of convenience, arrogance, or ignorance. It should not be interpreted as preventing us from ever reaching that conclusion after some careful consideration.