From: ksand@apple.com (Kent Sandvik )
Newsgroups: talk.religion.misc
Subject: Re: Criticism:  "There's no logic in Christianity"
Date: 6 Jan 93 20:04:16 GMT
Followup-To: talk.religion.misc
Organization: (Evil Eye Creature from Mars, Inc.)

In article <C04CrJ.Mv0.1@cs.cmu.edu>, drake+@cs.cmu.edu (Drake) wrote:
> ksand@apple.com (Kent Sandvik ) writes:
> >Sigh, my complain is that we all agree on the premisses of Eucledian
> >geometry, even if we can't verify them. At the other hand we *don't*
> >agree on the Christian premisses, making statements about logic and
> >Christianity something that we can't speak of. In other words moot.
> 
> *BRRAAAPP*
> 
> Sorry, Kent, that's wrong, but thank you for playing anyhow!  We have
> some very nice parting gifts...
> 
> I'm surprised that nobody has pointed this out yet, but nowhere is it
> claimed by any competent geometrist that the premisses (we mathemeticians
> like to call them 'axioms' or 'postulates') of Euclidean geometry are 
> in fact 'true.'  Not only do we have axioms (such as "In a plane, there
> can be drawn through any point A, lying outside of line a, one and only
> one straight line which does not intersect line a") but we also have
> undefined terms ("plane," "point," and "line," for example).

See my writing, I said 'agreed', it does not state that we know they
are right or wrong. And this is the core issue, if we agree upon
the a priory definitions, life is much easier concerning verification
of logical conclusions. 

> There is a difference, which you consistently fail to recognize, between
> "truth" and "validity."  This may help to point out the difference:
> 
> 	"If the premisses provide adequate grounds for affirming the
> conclusion, if asserting the premisses to be true warrants asserting
> the conclusion to be true also, then the reasoning is correct.  Otherwise
> it is incorrect."

Note the words 'if th epremisses provide *adequate ground for affirming
the conclusion' -- and this is the point I've tried to hammer on for
the last two weeks :-).

> 	All Catholics are human.
> 	I am a human.
> 	Therefore, I am a Catholic.
 
> Do you see how an argument can be both valid and untrue, or both invalid
> and true?  The important point is that if an argument is valid and logical,
> then the truth of the premisses *guarantees* the truth of the conclusion.
> Conversely, if one or both of the premisses can be shown to be false, then
> the conclusion is also false.

All of your examples stated premises that we both agree upon, in other
words no problems. However if we created statements consisting of
really non-agreeable premises, then we are in deep water once again.

> I suggest you study the above examples and come to a basic
> understanding of the rules of logic before you further embarass yourself
> by confusing truth and validity.  If you have any questions on these
> matters, please ask.

OK, I have a question, how do you define truth 1), if you know the exact
definition and agreement on this one, you could use truth in logical
constructs, if you don't, you are hosed :-).

Kent

1)Wittgenstein at his early age had an interesting notion of truth.
-------------------
Kent Sandvik (UUCP: ....!apple!ksand; INTERNET: ksand@apple.com)
DISCLAIMER: Private activities on the Net.		
"Don't just do something!  Stand there!"  -- Mystery Science Theater 3000
Xref: sparky talk.religion.misc:26042 alt.pagan:15302