The exception proves the rule. Just like the baker proves the bread or the watch proves the watch-maker. Right? No! That isn’t right at all and once and for all I’m going to this expose this principle for the fallacious tosh it is so it can be finally understood or buried.
Person 1 makes claim A
Person 2 points out exception to claim
Person 1 points out ‘perhaps that is the exception that proves the rule.’
How right person 1 is, but how little they know it. Let me furnish you with a real world example:
Brigadier Martinson: “I say! Haven’t you noticed that those bloody blacksmiths overcharge whosoever steps through into their workshop? They ought to be shot I tell you! Criminals and money-hoarders the lot of them.”
Cockney Pete: “Hold on old chap, what about James Horseshoe? He opted not to have a family so he could spend almost every penny of his earnings helping the poor in his village. Not only that but he’s by far the cheapest blacksmith in the land, he often charges less than it costs him to do the job, out of kindness of spirit.”
Brigadier Martinson: “Well dear sir perhaps he is merely the exception that proves the rule, what what!”
Okay maybe that wasn’t as ‘real world’ as I had aimed for but if you’ve any concept of who I am, you’d know I’m not all that connected to the ‘real world’ as those pesky realists have taken to calling it. If you don’t see a problem with that reasoning then this post is for you. With any luck, you’ll feel a small pang of embarrassment for every time you’ve said this and every time this has been said near you and you haven’t glared, sighed or expressed your vicarious shame in some other delightfully British way.
The issue results from a very simple mistake made by very simple people: ‘Prove’ is polysemic or, for the unenlightened amongst you, it has multiple meanings. To prove bread is the part of the bread-making process when you leave the warm yeasty dough to the side to allow the yeast to further develop. It has nothing to do with proof (i.e. scientific proof, logical proof or any other kind of evidence used to support a claim.)
To prove a theory is to provide evidence for it. When it has been evidenced, it has been proven. Another small misconception here is that when something is proven, it is 100% fact. For example, God has been proven not to exist. That is a fact. The statement ‘God does not exist’ has been proven over and over again. So, too, the statement ‘God does exist’ has been proven many times. They are true because evidence has been provided for both claims. As to which claims you agree with and which evidence you accept, that is a matter of personal choice and logic. You can scoff and call your scientific, atheist proof more sound than silly religious person proof but, actually, no proof is stronger than other proof. All claims are only accepted or not accepted and if a claim is accepted by more people, it says nothing about its truth.
Many people believed certain facts, such as the medical efficacy of leeches, that are not believed now. The popular opinion is to say that the claim is wrong and people were once wrong about it. The problem is, what is there to show how much righter we are? Evidence? Proof? Well they had that too. Just because we accept our evidence as being better, that means nothing about absolute truth. Only relative truth. After all, we may be more correct than the past and less correct than the future. Or maybe the future will agree with the past claims and our current opinion will be the one shown to be wrong. Again, scoff all you like, it’s the only response when you have no logic to combat with.
This was an aside however. The ‘prove’ in the phrase ‘the exception proves the rule’ refers to neither of these meanings and has a different meaning instead. It is the ‘prove’ used in the term ‘proving ground’. A proving ground is traditionally an area where a tribal warrior would prove their strength. But here is the key! That doesn’t mean he is displaying his strength and ‘proving’ it to the rest of the tribe. He isn’t providing evidence of his strength. He is testing it. He wants to know how strong he is, so he tests himself in the proving grounds (The testing grounds.) This is the meaning in our tragically over-used phrase.
When you make a claim in the form all A is B or, if you prefer, all A are B (such as all blacksmiths are greedy), that claim is deniable if you provide evidence to the contrary. Specifically, one non-greedy blacksmith would completely destroy the claim. If I have a pile of blank food tins and I say ‘All of these contain peaches!’ but then opening the first tin reveals baked beans, the claim is false. How can the claim ‘All these tins contain peaches’ be true if one or more contains baked beans instead? Does that actually make sense to anyone?
The purpose of the phrase is, as is shown by the meaning of ‘prove’ that you now know, ‘the exception tests the rule’. Apply that to our original argument. All blacksmiths are greedy. James Horseshoe is put forward as an exception. Thus the rule (or the claim) is being tested (or proven) and if the exception is shown to be sound, the rule will fall. So we talk to James Horseshoe and we all agree that he’s a great guy and not greedy in any way. The rule was proven and it didn’t pass the test.
So, when an exception appears, the rule is proven. It is put to the test and if the exception is a valid one, the rule cannot be true.
Do we all understand this now? Can I count on you all to never use this in public (or in private for that matter) again? If you all get it, this is one thing that the world won’t bother me about ever again, right? Brigadier Martinson was listening and he still doesn’t get it, but then, the exception proves the rule.