Path: utzoo!attcan!uunet!mcvax!ukc!warwick!mirk
From: mirk@warwick.UUCP (Mike Taylor)
Newsgroups: comp.ai
Subject: Re: Fun with the semantics of paradox
Keywords: Undecidable, Ambiguous
Message-ID: <905@ubu.warwick.UUCP>
Date: 16 Jan 89 14:33:20 GMT
References: <1883@buengc.BU.EDU> <2996@uhccux.uhcc.hawaii.edu>
Sender: news@warwick.UUCP
Reply-To: mirk@uk.ac.warwick.cs (Mike Taylor)
Organization: Computer Science, Warwick University, UK
Lines: 27

Two people have individually stated in this debate that there are 5
truth values, these being True, False, Ambiguous, Undecidable and
Meaningless.  It is intuitively clear to most people what is meant by
a sentence being either true or false.  The latter three categories
are not so clear.

Am I right in thinking that an ambiguous sentence is one that can
consistently be either true or false and that an undecidable one
cannot be either?  What, then is a meaningless sentence?  Surely
either an ambiguous sentence or an inconsistent one is meaningless?
Or do people simply mean not well-formed?

To clarify what I mean above by my understanding of the terms
ambiguous and undecidable, I suspect that the sentence "This sentence
is true" is ambiguous, since it can consistently be either true or
false, and "This sentence is false" is undecidable, since it cannot be
either.  Both sentences seem to me to be meaningless.

If this is correct, then Dave Peru's original assertion, that the mind
teeters between considering a paradox to be true or false, is correct
of ambiguous sentences, but not of undecidable ones - there is an
analogy here with unstable and unstable equilibrium points of a
physical system.
______________________________________________________________________________
Mike Taylor - {Christ,M{athemat,us}ic}ian ...  Email to: mirk@uk.ac.warwick.cs
*** Unkle Mirk sez: "Em9 A7 Em9 A7 Em9 A7 Em9 A7 Cmaj7 Bm7 Am7 G Gdim7 Am" ***
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