â€˜The exception that proves the ruleâ€™ is one of the most misused phrases in English. Yet itâ€™s also one that most people will have heard, so itâ€™s time to clarify how it should be used.
So strap in, sit back and enjoy this guide to when (and how) an exception can prove a rule.
The Origins of â€˜The Exception that Proves the Ruleâ€™
This phrase has its origins in an old Latin legal principle, which stated that â€˜the exception confirms the rule in cases not excepted.â€™ This means that when there is an exception to a rule, it shows that there must be a rule there (even when it isnâ€™t explicitly spelled out).
For example, if you see a sign saying â€˜No food or drink in the libraryâ€™, you can guess that food and drink is allowed elsewhere. So the exception (i.e. â€˜No food or drink in the libraryâ€™) proves that another rule must exist (i.e. â€˜Food and drink is permitted outside of the libraryâ€™).
So for any true pedants out there, this is the correct way that an exception can prove a rule. But this is not how the phrase is commonly used these days.
Its Modern Usage
Since old Latin legal principles arenâ€™t that popular any more, this phrase has taken on a new meaning: i.e. â€˜the exception that tests the ruleâ€™.
This is based on a definition of â€˜provesâ€™ that we also see in phrases like â€˜proving groundâ€™, â€˜the proof of the pudding is in the eatingâ€™, and even â€˜proofreadingâ€™. In all of these cases, â€˜proofâ€™ is a case of testing something to check that itâ€™s valid or correct.
An exception â€˜provesâ€™ a rule if it makes us question it or reject it. For example, we might believe the rule that â€˜everyone loves pizzaâ€™. The existence of one person who does not like pizza would then â€˜proveâ€™ or â€˜testâ€™ the rule.
Youâ€™ll want to avoid this usage in formal writing, as it is based on a confusion. But in conversation, people will know what you mean if you use the phrase this way.
How Not to Use the Phrase
There is, however, another way this phrase is used that makes no sense. This is when â€˜the exception that proves the ruleâ€™ is taken to mean that it can confirm a rule.
With this usage, finding someone who doesnâ€™t like pizza would be taken as evidence that everyone loves pizza. This is clearly absurd, as well as unfair on non-pizza fans (especially if you force them to eat one).
So take note: never use â€˜the exception that proves the ruleâ€™ to mean â€˜the exception confirms the ruleâ€™ if you want to be understood. If you think about it, itâ€™s just silly.