# Exception that proves the rule **URL:** \ **Category:** Factual Questions\ **Created:** [December 13, 2016, 2:08am UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578 "2016-12-13T02:08:10Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![obbn](https://avatars.discourse-cdn.com/v4/letter/o/d6d6ee/32.png) [@obbn](https://boards.straightdope.com/u/obbn)\ **Post date:** [December 13, 2016, 2:08am UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/1 "2016-12-13T02:08:10Z")
Hello Everyone, I’ve heard it hundreds of times, but I’ve never understood the saying “That’s the exception that proves the rule”. I mean if the rule is all cars are black and a blue one drives by how does that prove the rule? ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [December 13, 2016, 2:13am UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/2 "2016-12-13T02:13:45Z")
The original meaning was “The exception that _tests_ the rule.” It was a definition of “prove” that is not often used these days, but the OED includes it. So, in that case, it makes all the sense in the world. > [@OED](#): > > II. To make trial of; to try, test. > > a. trans. To put (a person or thing) to the test; to test the genuineness or qualities of; (Sc.) to test by tasting, to sample. Now rare in general use (but cf. technical uses at senses 6b, 6f, etc.). > > ?c1225 (▸?a1200) Ancrene Riwle (Cleo. C.vi) (1972) 138 Hwenne ha is ipreoued [c1230 Corpus ipruuet; a1250 Titus ipreouet] wel is hit iseit. for alswa preoueð [c1230 Corpus pruueð; a1250 Titus ipreoues] god hise leoue icorene. > c1330 (▸?a1300) Arthour & Merlin (Auch.) (1973) 3001 (MED), King and erls wiþouten dout Þer gun him anon rebout Forto prouen his maner. > a1400 (▸a1325) Cursor Mundi (Vesp.) 8115 Þe might o þam þou latt vs proue. > c1450 Alphabet of Tales (1904) I. 43 How þe fadir taght his son for to prufe his frende. So, in your example, the existence of a blue car tests the rule and shows it’s incorrect. Nowadays, meaning has changed and the phrase is read as “the exception that _becomes_ the rule.” ---
**Author:** ![Arkcon](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@Arkcon](https://boards.straightdope.com/u/Arkcon)\ **Post date:** [December 13, 2016, 2:15am UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/3 "2016-12-13T02:15:17Z")
Usually, “The exception that proves the rule” means the speaker has lost, and as just tried bluffing. But Wikipedia has a decent treatment: [Exception that proves the rule - Wikipedia](https://en.wikipedia.org/wiki/Exception_that_proves_the_rule) Basically, the exception proves\*\* another \*\*rule: right on top of that page --“No parking on Sundays” means, “You can park anytime from midnight Monday to Midnight Saturday”, and we don’t need a sign for that. ---
**Author:** ![Northern\_Piper](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/northern_piper/32/5304_2.png) [@Northern\_Piper](https://boards.straightdope.com/u/Northern_Piper)\ **Post date:** [December 13, 2016, 2:19am UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/4 "2016-12-13T02:19:59Z")
Tsk. Kids these days, citing that new-dangled Wikipedia thing. The true authoritative treatment of the question was of course provided by the Perfect Master 25 years ago: > **[What’s the meaning of the expression, “That’s the exception that proves the...](https://www.straightdope.com/21341901/what-s-the-meaning-of-the-expression-that-s-the-exception-that-proves-the-rule)** ---
**Author:** ![Arjuna34](https://avatars.discourse-cdn.com/v4/letter/a/eb8c5e/32.png) [@Arjuna34](https://boards.straightdope.com/u/Arjuna34)\ **Post date:** [December 13, 2016, 2:20am UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/5 "2016-12-13T02:20:18Z")
Cecil’s take: [What’s the meaning of the expression, “That’s the exception that proves the rule?”](http://www.straightdope.com/columns/read/731/whats-the-meaning-of-the-expression-thats-the-exception-that-proves-the-rule) ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 13, 2016, 3:47am UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/6 "2016-12-13T03:47:25Z")
Good grief. The Fowler quote Cecil cites is incomprehensible to its core. Nobody should ever cite Fowler on anything. The only exception is to show that even Fowler allows it, hence, it has been good English for a century and only illiterate pedants would think otherwise. That may be the exception that proves the rule. Ha. No it aint. It’s a reason to not cite Fowler on anything because anything the illiterate pedants claim is automatically false and you don’t need Fowler to make your case. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [December 13, 2016, 11:38am UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/7 "2016-12-13T11:38:54Z")
> [@RealityChuck](#): > > The original meaning was “The exception that _tests_ the rule.” It was a definition of “prove” that is not often used these days, but the OED includes it. So, in that case, it makes all the sense in the world. > > So, in your example, the existence of a blue car tests the rule and shows it’s incorrect. > > Nowadays, meaning has changed and the phrase is read as “the exception that _becomes_ the rule.” Yeah its all that. It means if you understand why the exception is an exception, you’ve got the understanding of the rule… whats in, whats out… Its pedantic to try work out what meaning of “test” or “proof” or “becomes” it is… Its just understanding, which means you understand the meaning of whatever word you prefer to put there… What i mean is that a more generic expression, that doesn’t risk a pendant saying you’ve used the wrong word… could be “An exception that helps you understand what the rule is and isn’t.” It would be more general to change “exception” to “example”… but this thread is about how an exception “proves” the rule. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [December 13, 2016, 12:38pm UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/8 "2016-12-13T12:38:25Z")
since cites have already been given, all I can say is that I usually only hear that from someone when they steadfastly refuse to admit they might be wrong. ---
**Author:** ![DrFidelius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drfidelius/32/3447_2.png) [@DrFidelius](https://boards.straightdope.com/u/DrFidelius)\ **Post date:** [December 13, 2016, 1:06pm UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/9 "2016-12-13T13:06:40Z")
I usually say it as “The exception proofs (or probes) the rule” and people just stare at me uncomfortably. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [December 13, 2016, 1:50pm UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/10 "2016-12-13T13:50:45Z")
The rule seems to have become ‘there is an exception to every rule’ in the minds of some. Not the way the root expression was intended, if at all it derives from that, but a convenience to deal with simple rules that usually won’t be all encompassing. ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [December 13, 2016, 2:38pm UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/11 "2016-12-13T14:38:12Z")
I always understood that the quotation refers to the older meaning of prove, namely test. That meaning survives in closely related words: e.g. photographic proofs are test samples; Aberdeen Proving Grounds are obviously testing grounds. Even in mathematics, where proof normally means verify, I still recall one instance of the older meaning. In a translation of Gauss’s Disquitiones Arithmeticae, I discovered the following surprising statement (more-or-less; I am doing this from memory): Lagrange proved this by induction, but we give the first demontration by infinite descent. In modern language, proof = demonstration and induction = infinite descent. But the translator chose (incorrectly, IMHO, in 1962) to use English cognates for the Latin words. So what Gauss was saying that Lagrange had tested this statement in a great many cases and proclaimed it, while Gauss was actually proving it by mathematical induction. ---
**Author:** ![DrCube](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@DrCube](https://boards.straightdope.com/u/DrCube)\ **Post date:** [December 13, 2016, 2:51pm UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/12 "2016-12-13T14:51:41Z")
I’ve taken it to mean that if something is odd or weird or rare enough to get noticed, that proves that the “rule” is right most of the time. For example, nowadays nobody cares if they see a blue car drive by. It’s expected. But if the rule were more or less “all cars are black”, then the sight of a blue car would be an exciting enough event that people would talk about it. And the fact that it is exciting enough to mention and discuss demonstrates that the rule holds true most of the time. Another example is that flying pigs are seen as an extremely unlikely event. Nobody would say “When pigs fly!” if the rule, that pigs don’t fly, wasn’t considered by everyone to be pretty solidly grounded. In other words it’s (the response to) the (rare) exception that proves the rule (is right most of the time). If that makes any sense. The other posters are correct as to the phrase’s origin and background, however. ---
**Author:** ![Blue\_Blistering\_Barnacle](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/blue_blistering_barnacle/32/3386_2.png) [@Blue\_Blistering\_Barnacle](https://boards.straightdope.com/u/Blue_Blistering_Barnacle)\ **Post date:** [December 13, 2016, 3:05pm UTC](https://boards.straightdope.com/t/exception-that-proves-the-rule/774578/13 "2016-12-13T15:05:24Z")
> [@TriPolar](#): > > The rule seems to have become ‘there is an exception to every rule’ in the minds of some. …snip… What’s the exception to that rule? 🙂