DOES THE EXCEPTION PROVE THE RULE?

DOES THE EXCEPTION PROVE THE RULE? I have had a long-running debate with Mary Jane about what it means to say, “The exception proves the rule.” Mary Jane has contended that the word “proves” is to be taken with the older meaning of “to test” (as in the “proof of the pudding”) so that the phrase is to be interpreted as, “The exception tests the rule.” This article from an interesting site acknowledges that many reference works agree with this view: “If you can’t reconcile the supposed exception with the rule, there must indeed be something wrong with the rule.” But that site supports what I think is the correct view, which goes back to a Medieval Latin rule of construction. Wikipedia says, “The presence of an exception establishes the existence of a stated rule. For example, a sign that says ‘parking prohibited on Sundays’ (the exception) suggests that parking is allowed on the other six days of the week (the rule).” The Latin phrase is: “exceptio probat regulam in casibus non exceptis (‘the exception confirms the rule in cases not excepted’)” and can be traced back to Cicero. This is why I argue that Shakespeare portrays Brutus and Hotspur as having good marriages except in extreme circumstances. They share and live in intimacy with their wives with one exception–when they are planning extremely dangerous actions.