What is proof?

I might have posted about this mistake before, but here’s a nice comic to remind you about it. People misinterpret “the exception proves the rule”  almost  as often as they get “beg the question” wrong ( I’ve written about that one, too.). Recently I discovered a comic that’s been around at least since 2007 (so I have some catching up to do in my copious spare time), and a recent strip mentions this expression.

Kieran Meehan writes a clever strip about some professional people and crooks called Pros and Cons. Here’s the strip:

I haven't figured out all the characters, but the gal on the right runs a diner and she's the sister of one of the other characters

Most people (in my experience, anyway) think that the exception proving a rule means that when something breaks a rule, it illustrates the existence of the rule because you notice the exception to it. BRAAP! Completely wrong.

“Prove” is an old word for “test.” There’s the famous reference to tithing in the Old Testament book of Malachi that goes “Prove me now herewith and bring all the tithes into the storehouse…” We still use the word prove in a testing sense in certain contexts, such as when someone says something like “Well, let’s see if the plane proves airworthy.”

What this expression means is that to really find out is a rule is for real, you have to break (the exception) it (the rule) and see what happens. If something bad happens because you broke the rule, yup, it’s a rule, all right. If nothing happens, it wasn’t relly a rule in the first place.

Children do this to their parents all the time. Don’t make a rule unless you’re willing to enforce it. Does this comic get the expression right or wrong? I’m not sure—I haven’t figured it out yet, but it’s funny.