The adage “Exceptions prove the rule” is one of the silliest I’ve heard. It is too obviously illogical and I can’t think of a situation where it actually makes sense. So I was happy to learn that it is actually a backward compatibility issue.

Long long ago, “to prove” meant “to test”. Then, “Exceptions prove the rule” meant, “Exceptions test the rule”. The latter makes perfect sense, but unfortunately lacks the epigrammatic quality that the former has acquired.

There are many other phrases and usages based on the original sense of “prove”, but their meaning hasn’t changed so drastically.

• The proof of the pudding is in the eating
• Prooving ring (where they test cars)
• Foolproof

It was such a minor change in usage. From “to test” to “to pass the test”, but it caused an increase in the amount of Nonsensical Particulate Matter floating in the air.