The exception proves the rule - explained
The exception proves the rule
the meaning has been reversed. Actually, this expression means -
The exception disproves the rule.
This is because when the expression was first popular, the word *prove* was neutral, that is, it meant that it didn't express good or bad, true or false. It just meant *test*. The closest thing to the original meaning of the word prove today can be found on a *proving ground*, where cars are tested. So, the original meaning was *the exception tests the rule*. And since something can be proven wrong, the expression means exactly the opposite of what many people think it means today.
If you have an exception to a rule, for example *all goldfish are gold*, and you find an exception, as in finding a goldfish that isn't gold, you have tested (or *proven*) the rule. And your rule is false. Of course today when we say that something has been proven, we mean it's true.
Maybe in another 150 years, there will be new misinterpretations!
Posted by Brad Hall