No it's not. It's because the meaning of the English word "prove" has changed. It used to mean "test", which could of course have a positive or negative outcome

No it's not. It's because the meaning of the English word "prove" has changed. It used to mean "test", which could of course have a positive or negative outcome. The modern sense of "successfully demonstrating truth" has caused this phrase to have the opposite of its original meaning. [0] https://www.oed.com/dictionary/prove_v?tl=true https://www.oed.com/dictionary/prove_v?tl=true