Message-Id: <m0qnSCV-00005XC@xiron.pc.helsinki.fi>
Date:         Wed, 21 Sep 1994 09:43:21 -0400
Reply-To:     Logical Language Group <lojbab@ACCESS.DIGEX.NET>
Sender:       Lojban list <LOJBAN%CUVMB.bitnet@FINHUTC.hut.fi>
From:         Logical Language Group <lojbab@ACCESS.DIGEX.NET>
Subject:      Re: any? (response to Desmond)
To:         lojban@cuvmb.cc.columbia.edu
In-Reply-To:  <199409210715.AA28528@nfs1.digex.net> from "Desmond
              Fearnley-Sander" at Sep 21, 94 11:19:27 am
Content-Length: 2268
Lines: 49

la dezmnd. cusku di'e

> Surely not.  I may know a lot about Charles and Diana but not know whether
> they live in the same county.  I lack that specific information.  For me
> the sentence "Charles and Diana live in the same county." is neither true
> nor false.  Of course *in fact* it is either true or false, but that is not
> a linguistic matter.  (I like the idea that language and reality are
> independent worlds, that language is for conveying and analysing
> information and that matters of fact only impinge on language by
> influencing what we find worth saying.  Philosopher's might have a field
> day with this.  I'd better retract it.)

Indeed.  I think that you are on firmer ground to say that "C. and D. live
in the same county" is either true or false >tout court<, but that you don't
know which.  This puts the problem onto knowledge (epistemology), which is
known to be a sticky area, and leaves truth value simple.

Three-valued logics can be made to work, but they are messy.  Instead of
a single clear negation operator, transforming truth into falsity and falsity
into truth, you end up with five operators:

        ~T = F, ~F = T, ~U = U (swap true and false: standard negation);
        ~T = F, ~F = U, ~U = T (rotate left);
        ~T = T, ~F = U, ~U = F (swap false and unknown);
        ~T = U, ~F = T, ~U = F (rotate right);
        ~T = U, ~F = F, ~U = T (swap true and unknown);

plus a bunch more that aren't invertible, like T -> F, F -> U, U -> U.

> John Cowan:
> >Nah.  Too late now.  Use "le" throughout instead.
> >
> That also makes sense to me.  I would be interested in the simplest lojban
> rendering of
> (1)  A man is eating an icecream.  The man is happy.
> (2)  Two people are in a room.  The man is happy.
> (3)  A man may eat an icecream.  A man may be happy.
> (4)  A man may eat an icecream.  That would make him happy.

Without worrying about Lojban vocabulary, it comes out:

1) le -man -eats loi -icecream .i le -man -happy.
2) re lo -persons -in le -room .i le -man -happy.
3) lo -man (modal) -eat loi -icecream .i lo -man (modal) -happy.
4) lo -man (modal) -eat loi -icecream gi'e -happy.

--
John Cowan              sharing account <lojbab@access.digex.net> for now
                e'osai ko sarji la lojban.