🚀 go-pugleaf

Hmmm... rather to my astonishment, it appears that the word "logic" here
is becoming polymorphous.  On at least one hand, we have a very general
idea of logic as "the study of the principles of reasoning" or "valid
reasoning as opposed to invalid reasoning".  On another hand, we have
the much more constrained definition of formal or mathematical logic.
(An appropriate Peano axiomatization leading to the generation of
infinite hands is left as an exercise.)

I believe that the original question was really in the first domain, so
it isn't clear that the mathematical arguments -- while interesting in
themselves -- are very informative.  Considering the question from the
more general position, it appears that the original question

   Can anyone explain why we use logic? Unfortunately, any logical
   arguments to support logic, are unfortunately, invalid.  --Ray Cote

is clearly an attempt to attack the use of "logic" by paradox, by
claiming that there is no "logical" reason to use logic.  However, as
someone else pointed out, the question presumes an appeal to logic on
its face, because the distinction between a "valid" and "invalid"
argument is itself a logical one.  One might argue therefore that the
best argument for using logic is the fact that the attempt to challenge
the use of logic must itself appeal to "logic", that is, to valid
reasoning.  This can lead to the idea of a Platonic Form for "valid
reasoning" that pre-exists our attempts to use that valid reasoning,
making "logic" into a sort of natural-science search for a better and
better description of this Ideal of Valid Reasoning.

More pragmatically, there appear to be only two forms of reaching
agreement available: either we appeal to an idea of "valid argument"
under which, by a dialectic or discursive process, we arrive at a
conclusion acceptable to all parties; or we deny that such a process can
exist, in which case we are reduced to the more direct method of hitting
one another over the head with large rocks until one side or the other
gives in.

--
		Charles R. Martin/(Charlie)/martinc@cs.unc.edu
     Dept. of Computer Science/CB #3175 UNC-CH/Chapel Hill, NC 27599-3175
	    3611 University Dr #13M/Durham, NC 27707/(919) 419 1754
     "Oh God, please help me be civil in tongue, pure in thought, and able
      to resist the temptation to laugh uncontrollably.  Amen." -- Rob T