I’m a word nerd, and recently I found an interesting article explaining the phrase, the exception proves the rule.
I always found this concept baffling — how does an exception prove a rule? But the author pointed out that prove didn’t always mean what it does today. It comes from the Latin probare, which actually meant test.
You can see this in the phrase proving ground…not a place to confirm weapons exist, but to make sure they work. Or proofreader, someone who “tests” copy before it’s printed to make sure it’s not full of typos and bad grammar.
So when we say the exception proves the rule, what we’re really saying is the exception tests the rule. And that makes a lot of sense. When you test a rule, it may be confirmed or you might discover it’s not such an ironclad rule.
In our business, there are a lot of rules: People won’t read long copy. Don’t deploy emails on Friday. Reverse type is hard to read. Subject lines should be 6 to 10 words. Et cetera.
There are good reasons for these rules. But another rule in our business is test, test, test. Why? Because you can’t find the most effective way to sell something until you try a bunch of different approaches.
In other words, the exception proves the rule.
P.S. Ever wondered why it’s called a rule of thumb? People who study things like this think it’s because in the old days, carpenters sometimes estimated inches using the width of their thumbs if a ruler wasn’t handy. In many languages, including Dutch, French and Italian, the same word is used for thumb and inch.