How can an exception prove that a rule is valid?

Question

I really don't understand... people often say 'It's an exception that proves the rule." But how can it? If there is an exception, then the rule must void, no?

Answer 1

Good question!!



I agree with you that an exception doesn't prove the validity of the rule; instead it disproves the universality of the rule. However, the existence of an exception can only arise once a rule is well understood to 'generally' exist.... it is in this sense that an exception proves the existence of the rule.

Answer 2

An exception does not prove a rule is valid - it's just a very common misconception.



This is what formal logic says about rules:

1. A rule can hold even if it has exceptions, provided that the exceptions are clearly specified within the very definitions of that rule.

2. When you define a rule you need to be thorough in specifying all its exceptions. If exceptions are found afterwards that you have not specified in the definition of your rule, then your rule will become invalid.

3. The more exceptions to a rule, the weaker the rule is.



Yes, it is likely that "prove" in that context actually means "test". It is the only way the assertion "The exception proves the rule" can make any sense.



I've also heard people saying "The exception makes the rule" and I take it to mean "Do a good job of describing the exceptions of whatever rule you're defining, and then you will have a strong rule"

Answer 3

could you offer an example please? i dont know if this thought is applicable across the board or not. offer an example of a rule and we will analyze it as well as the exception and try to understand the connection.



Edit: someone used the example of a coin toss. i like this. the rule is that the coin will land with either the heads or tales side facing up. the exception is that it will land on its edge. in this case, i dont think it proves the rule. it expands the rule. now the rule is a coin will land on either a flat side or an edge. its kind of like roulette. you can bet on either black or red if you wish, so the rule is that the ball will land on either black or red. there is an almost 50/50 chance of the ball landing on either black or red. but there is i think a %2 chance (or something like that) that the ball will land on 0 or 00 which are green. this is how the casino makes a profit, so if the casino were to ignore the exception, then they would eliminate that aspect of the game because they could only break even if they accepted the rule. they expand the rule to red, black, or green, but try to give the impression that the rule is only black or red so people think the odds are 50/50.

Answer 4

Nothing is absolute (in man's world) so an exception DOES NOT prove a rule wrong. The expression is the flip side of that idea. Finding ONLY ONE exception suggests the rule is valid.

Answer 5

What is provable and what is valid as a theory is a matter the philosophy of science. This however is common understanding that if there wouldn't be any exceptions if there weren't any rules, without rules anything would be possible and all possibilities valid. There therefore are no rules without their exceptions, as any rule without exception would be absolute. And are there any absolute rule? Only natural laws are absolute.



All rules, by their very definition, as made by man, are exceptional, and nothing made by man is made perfect, is the only rule absolute ... as if man were capable of perfection there wouldn't be any need for rules; everything then would become perfect, without exception. So, rules are there as there are exceptions; and there are no rules without exceptions, aside natural laws.



If you then toss a coin it will fall to the ground, hundred percent, as according to the law of gravity, and then it will settle on to the one of its sides whereby its centre of gravity is closest to its point contact with the ground of its rest, as this is natural rule that all things settle in their optimum state of balance.



The resting of coin on its edge is a possibility of its happening only in the mind, however remote it might in the mind it is there, as given the right natural conditions, a coin will settle of it edge if this is the best position for it to settle – as it happens when you role a coin, or when it rolls down a slot-machine.

Answer 6

Well first of all there are absolutes rules and general rules, and you use this way of saying with general rules...



...it means that if there is only very few cases against the rule, we can consider it still valid...



The concept is:

you can't attack a general rule that works 998 times on 1000, by showing the very few cases that don't match the rule. If you wanna attack such a rule you have to provide a new rule that works better...otherwise that old rule is still valid (untill someone will find a better one, of course)

Answer 7

When that phrase first started being used the word "prove" meant "test". It should now read: "An exception tests the rule".

Answer 8

It applies to simple things that can have an unusual outcome.I will give one example .Take a coin and toss it in the air it will either come down heads or it will come down tails but occasionally it should land, and I have never seen it happen , on its edge. Or it is an event that only happens when certain different conditions are met meaning it will always have the same outcome except when this occurs.

Answer 9

The meaning of words changes. The original meaning of 'prove' was to test, not to show something was true. Thus the exception 'tests' the rule, it does not confirm it.



The original meaning of 'prove' also remains in 'The proof of the pudding is in the eating', i.e. you can only test how good a dessert is by eating it.