"The exception proves the rule."

[BurtWorm]

Do you ever use this term? Or the related "the exception that proves the rule?" Then you might be interested in this explanation of the term. It cleared up my own bafflement over the way the phrase is commonly used, which doesn't make a damn bit of sense:

http://www.worldwidewords.org/qa/qa-exc1.htm

These days it is often used sweepingly to justify an inconsistency. Those who use it seem to be saying that the existence of a case that doesn’t follow a rule proves the rule applies in all other cases and so is generally correct, notwithstanding the exception. This is nonsense, because the logical implication of finding that something doesn’t follow a rule is that there must be something wrong with the rule. As the old maxim has it, you need find only one white crow to disprove the rule that all crows are black.

It has often been suggested in reference works that prove here is really being used in the sense of “test” (as it does in terms like “proving ground” or “the proof of the pudding is in the eating”, or in the printer’s proof, which is a test page run off to see that all is correct with the typesetting). It is said that the real idea behind the saying is that the presence of what looks like an exception tests whether a rule is really valid or not. If you can’t reconcile the supposed exception with the rule, there must indeed be something wrong with the rule. The expression is indeed used in this sense, but that’s not where it comes from or what it strictly means.

The problem with that attempted explanation is that those putting it forward have picked on the wrong word to challenge. It’s not a false sense of proof that causes the problem, but exception. We think of it as meaning some case that doesn’t follow the rule, but the original sense was of someone or something that is granted permission not to follow a rule that otherwise applies. The true origin of the phrase lies in a medieval Latin legal principle: exceptio probat regulam in casibus non exceptis, which may be translated as “the exception confirms the rule in the cases not excepted”.

Let us say that you drive down a street somewhere and find a notice which says “Parking prohibited on Sundays”. You may reasonably infer from this that parking is allowed on the other six days of the week. A sign on a museum door which says “Entry free today” leads to the implication that entry is not free on other days (unless it’s a marketing ploy like the never-ending sales that some stores have, but let’s not get sidetracked). H W Fowler gave an example from his wartime experience: “Special leave is given for men to be out of barracks tonight until 11pm”, which implies a rule that in other cases men must be in barracks before that time. So, in its strict sense, the principle is arguing that the existence of an allowed exception to a rule reaffirms the existence of the rule.

[Oeditpus Rex]

1. All it proves

is the existence of the exception.

[billyskank]

2. It's far simpler than that

"Those who use it seem to be saying that the existence of a case that doesn’t follow a rule proves the rule applies in all other cases and so is generally correct, notwithstanding the exception."

Not really. It's just what people say when you point out that what they said is a load of shite and they need an immediate comeback.

[BurtWorm]

3. If I am the only other person to respond besides you and Oeditpus Rex

am I the exception that proves the rule that people who respond to this thread have guitar playing gifs in their signatures?

:crazy:

[Oeditpus Rex]

4. Well, you could also say

that my acoustic-guitar-playing lizard (an Austin Lounge Lizard, specifically) is the exception that proves the rule of emo lemons playing electric guitars.

:shrug:

[ThomCat]

5. I disagree.

In situations where one outcome is so incredibly common that an exception stands out and gets noticed, the fact that the exception is an exception, the fact that it so rarely occurs, proves that the far more common result is a general rule.

If you're looking for absolutes, where there are no exceptions, then you would be correct. But in situations where various outcomes are possible and reasonable, the fact that one outcome predominates is important to note, and it's the rarity of exceptions that proves that general rule.

Hence the expression. "It's the exception that proves the rule."

[BurtWorm]

6. But that's a back-formed meaning, shoehorned onto a phrase

that was clearly meant to apply to another instance entirely, as the grammarian's explanation makes indisputably clear.

It's almost exactly like what has happened to the phrase "begging the question," which has come to mean "begging for a certain question to be asked." But that is demonstrably not what that phrase meant originally, as it was translated from the logical term petitio principii, which refers to an argument that uses the premises to "prove" the premises ("God exists because when he wrote the Bible, he said he exists and God doesn't lie.")

I say it's almost exactly like this case because at least "begging the question" sounds like it could mean "raising an implied question." The "exception that proves the rule" just doesn't make sense, as the grammarian points out.

[ThomCat]

7. I've never heard that it applied to any other instance.

As far as I've always known, my definition is exactly what it means. Any outcome so common that the existence of an exception proves a general rule. It makes perfect sense to me.

As for "Begging the question," that has always meant "implies an assumption that should be questioned."

[BurtWorm]

9. You have to step away from your use to look at the nonsense inherent in it.

An exception does NOT prove a rule in logic. On the contrary, it proves that the rule needs to be reworked. Take the example given: Does the instance of a black swan prove the rule that "All swans are white?" Not at all. In fact it destroys the rule in one fell swoop. It really makes no sense to say to someone, "See? That black swan just proves how right I am when I say 'All swans are white.' QED." Logic doesn't work like that.

[ThomCat]

10. Just because you don't understand it doesn't make it nonsense.

It makes perfect sense. We're not talking about formal logic. Get your head out of the book and look at real life.

[BurtWorm]

12. Show me how one instance of a black swan proves the rule "all swans are white"

and I'll agree with you.

[ThomCat]

13. How about a more realistic example.

The fact that a boy who plays with barbie dolls is rare and draws attention is the exception that proves the rule that barbie dolls are a girl's toy.

The fact that people are shocked when a woman knows how to work on a car is an exception that proves that working on cars is a man's hobby.

The fact that everyone says, "ThomCat, you're watching TV?" is would the the exception that proves the rule that I don't like to watch TV and very rarely ever do.

You're thinking in terms of absolutes. This is an expression that deals with social and political general rules.

[BurtWorm]

14. "Thom Cat does not generally watch TV except when he watches TV" is a meaningless tautology.

"Exceptio probat regulam in casibus non exceptis: the fact that certain exceptions are made confirms that the rule is valid in all other cases."

Is it a rule that Barbie is a girl's toy? Or that working on cars is a man's hobby? Or that you don't watch TV? No. They're tendencies. All of the above are subject to change, to fads and fashions and social or personal moods. It certainly does not "prove" that you don't watch TV if someone finds you watching TV. It proves the opposite, that you do sometimes watch TV.

[ThomCat]

15. That's fine.

If you're going to confine your discussion to formal rules of logic then follow your own rule. Stop asking about expressions that don't apply to formal logic.

[BurtWorm]

16. The point is that the expression as it is commonly used is nonsensical.

I will grant that your instances of it seem to hold some tiny relic of the original meaning, insofar as they actually offer up unusual exceptions to what might be, as you say, informally taken as "rules." But it is wrong to say that these instances are perfectly matched to the expression. Clearly, someone who didn't know what the expression meant borrowed it imprecisely to fit this kind of instance you're talking about, in the same way that someone borrowed "begging the question" to fit an instance other than "circular reasoning."

By some strange mechanism of language usage, these misappropriations came into common use. Similarly, people commonly use "nauseous" for "nauseated," "infer" for "imply," "ecksetera" for "et cetera," etc. When you get right down to it, they're just sounds after all, so as long as people understand what you mean, what's the difference, right?

[Hugin]

8. The problem is...

I'm a 'linguarian' and not a 'grammarian'.

So, to me... THE QUESTION IS MOOT!

[BurtWorm]

11. Can we keep your tongue out of this?

:crazy:

[Hosnon]

17. Very good to know. The incorrect use of "begging the question" has

always pissed me off and it appears that I have been using "the exception that proves the rule" wrong.