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From: rlr@pyuxd.UUCP (Professor Wagstaff)
Newsgroups: net.philosophy
Subject: Re: Rosen on logic and proof
Message-ID: <748@pyuxd.UUCP>
Date: Fri, 22-Mar-85 20:45:09 EST
Article-I.D.: pyuxd.748
Posted: Fri Mar 22 20:45:09 1985
Date-Received: Sat, 23-Mar-85 03:51:01 EST
References: <844@wucs.UUCP>
Organization: Huxley College
Lines: 66

>>Hardly.  If by rational, you imply something about decision-making processes,
>>well, don't rivers and rocks make "decisions" about which way they will flow
>>and fall?  Quite rational, they way they make those "decisions"...  [ROSEN]

> No it isn't rational, that's the whole point.  Only a Humpty-Dumpty would
> describe the processes in rivers and rocks as "rational".  [TOREK]

Didn't the water make a rational decision to go flow in the direction of the
rest of the river?  Didn't the rock make a rational decision by deciding to
fall downward and not work against the gravitational force?  What's that you
say?  They're NOT deciding?  How can you say that?  In what way are the rock's
processes of decision different from ours?  (I think we actually get to this
later.)

>>Can you prove that [logic] is truth-preserving?  Especially when the 
>>definition of truth and falsehood, concordance and contradiction, are 
>>fundamental to the notions of logic.

> Yes, you can prove that logic is truth-preserving, though of course you 
> have to use logic to do it because you have to use it to prove *anything*.
> And of course a proof is not likely to win any *new* adherents to logic.

If you use the method to "prove" the truth-preservingness of the method,
you have proven NOTHING.

> The notion of proof involves making no assumptions about the *truth*/falsehood
> of a statement.  Logical laws are rules of inference however, not statements,
> and neither true nor false.

Why?  Because you say so?  Because you take them as givens!  You say that they
are neither true nor false simply because you cannot prove that either way.
I agree with you about the nature of logic, Paul, but the point is not
that you don't have to prove them, it's because they are *defining* certain
terms.  One has to get all the way back to the very nature of what assumptions
underly the definitions.

>>>Read again what I said (edited [now twice], but meaning unchanged):
>>> Carroll ... shows ... that reason is not a premise but rather the 
>>> way of getting from premises to conclusions. 

>>THIS, what you've just said, is a premise!  Prove it!  (That's the whole 
>>point here.)  

> That reason is not a premise?  That follows from the fact that it's a rule
> of inference, which is different.

Solely because you say so?  It's not "different", except in the way I describe
above (i.e., its basis in definitions).

> That's what Carroll proved, that reason's function is not performed by
> treating it as a premise.

What Carroll showed was the paradox of trying to prove logic with logic.  NOT
that you have no reason to do so.  He's probably spinning in his grave after
hearing your contention that he was trying to show that reason shouldn't be
treated as a premise!  It's funny that you interpret it that way---it seems
to highlight your assumptions about logic.  (I never thought I'd be arguing
THIS side of the logic issue!)

I'm reminded the scene in Annie Hall when Alvy Singer pulls Marshall McLuhan
out from behind a billboard to tell some pompous buffoon that he's got his
(McLuhan's) notions all wrong.  (Not to imply that you're a pompous buffoon.)
"Why can't real life be like this?"
-- 
"Which three books would *you* have taken?"
				Rich Rosen	ihnp4!pyuxd!rlr