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Re: 1 Jn 2:19 and universal negation - yes!

On Sun, 8 Jun 1997, Micheal Palmer wrote:

> At 6:51 PM -0700 6/5/97, Paul Dixon - Ladd Hill Bible Church wrote:
> >IAKWBW KAI TOIS PISTOIS:
> >
> >I agree with Jim that 1 Jn 2:19 is "conclusively" a universal negation,
> >but not because of the OU+VERB+PAS  construction (which may yet support
> >this), but because of logical reasons.
> >
> >The last part of verse 19, "but that they may be manifest that OUK EISIV
> >PANTES EC HMWN, is the contrapositive of the immediately preceding
> >conditional, "if they had been of us, then they would have remained with
> >us."  For those of you unfamiliar with this reasoning - the contrapostive
> >is the only universal negation implied by a conditional ("If A, then B"
> >implies the universal negation "if not B, then not A").
> 
> Surely you don't mean that
> 
> 	If Fido is a dog, then he is a canine
> 	[If A		, then B]
> 
> implies the universal negation
> 
> 	If Fido is not a dog, then he is not a canine
> 	[If not A	    , then not B]
> 
> do you?

Michael:

As they say at Hertz, "Not exactly."  The contrapositive of

	If Fido is a dog, then he is a canine
	[If A           , then B]

is

	If Fido is not a canine, then he is not a dog.
	[If not B              , then not A].

Let's get this straight, please.  :)

Now if this still does not make much sense to you (you're possibly
thinking this is a truism), then it is because you selected a
bi-conditional statement (what definitions are made of, i.e., dog being
defined as a canine).  This still works, of course, but if you want to
really appreciate the goings-on, then just stick to a conditional, like:

	If Fido is a dog, then he is an animal.
	
Therefore,

	If Fido is not an animal, then he is not a dog.


Paul Dixon
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