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Topic: 2.25 - The meaning of "implies" in mythmatics.
Replies: 3   Last Post: Jul 24, 2014 3:37 PM

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 YBM Posts: 846 Registered: 11/27/09
Re: 2.25 - The meaning of "implies" in mythmatics.
Posted: Jul 24, 2014 6:28 AM

Le 24/07/2014 09:09, John Gabriel a écrit :
> "If John Gabriel is always right, then John Gabriel is never wrong."
>
> Suppose that p = John Gabriel is always right and that q = John Gabriel is never wrong.
>
> Then according to the nonsensical imply truth table:
>
> ¬p OR q
>
> Assume p and q are FALSE.
>
> Then, ¬FALSE OR FALSE = TRUE.
>
> So, if "John Gabriel is always right" is FALSE (that is, John Gabriel is NOT always right), then *John Gabriel is always right*

No crank, if q is FALSE (John Gabriel is NOT always right) then
(p => q) is TRUE (that is "John Gabriel is always right" => "John
Gabriel is never wrong"), but this says nothing about truth of q
('John Gabriel is never wrong').

What mysterious reason makes you think that if (p => q) is TRUE, then
q is necessarily true?

Date Subject Author
7/24/14 YBM
7/24/14 Tucsondrew@me.com
7/24/14 Brian Q. Hutchings