Message-Id: <m0rgdaK-00001pC@xiron.pc.helsinki.fi>
Date:         Mon, 20 Feb 1995 14:17:22 EST
Reply-To:     jorge@PHYAST.PITT.EDU
Sender:       Lojban list <LOJBAN%CUVMB.bitnet@FINHUTC.hut.fi>
From:         jorge@PHYAST.PITT.EDU
Subject:      Re: status of lo/dapoi, here are some messages from the old thread
To:           Veijo Vilva <veion@XIRON.PC.HELSINKI.FI>
Content-Length: 2857
Lines: 69

la lojbab cusku di'e

> |1. Therefore the statement "Elves have pointed ears" is false since
> |there is no such thing as an elf. Likewise definitional statements
> |"Elves are humanoid" is also false even if definitional.  How can you
> |describe the properties of a hypothetical but non-existent object if any
> |statement about such an object is false.

Those statements don't cause trouble because they are quantified by {ro}.
"All elves are humanoid" can be true even if there are no elves, and
can also be part of a definition even if there are no elves.

"At least one elf is humanoid", on the other hand, to be true requires
that there be at least one elf.

"At least one elf is humanoid" is true if by elf you mean the character
of fiction elf, and you allow the predicate "...is humanoid" to apply to
characters of fiction. (It obviously doesn't apply to numbers,
"3 is humanoid" is nonsense, but it may apply to other abstract
objects.)

The sentence can also be true, of course, within a work of fiction.

It can't be the case that:

        lo pavyseljirna cu pavyselcirna
        At least one unicorn is a unicorn.

is true and at the same time:

        no da cu pavyselcirna
        There is nothing that is a unicorn.

To me, these two are contradictory. Therefore, if {lo pavyseljirna
cu pavyselcirna} is true, then {da poi pavyselcirna cu pavyseljirna}
is also true.

> |2. If statements about non-existent objects are false, then their
> |negation is true.  We can possibly weasel around this with "na" negation
> |(and I think I did in the negation paper), but I am not sure.

The negation of a false statment is a true statement. I don't think there
is any problem with that in this case.

> |3> And then there is the argument that all statements about non-existent
> |objects being equivalent to each other, since all are statements about
> |the members of the empty set.

Yes, but what is a non-existent object? A unicorn is not a non-existent
object. There is no such thing as a real life animal that has all the
properties ascribed to unicorns, but the unicorn as a mythological
character exists as a mythological character. Or would you say
that noda is a mythological character?

> |But the status quo remains, as far as I know, that "lo [unicorn] cu
> |brode" is not the same as da poi [unicorn] cu broda.

And what is the difference? Is {lo pavyselcirna cu pavyseljirna} true?
Is {noda pavyseljirna} true?

The problem is not with {lo} or {da poi}, the problem is how
you define the selbri {pavyseljirna}. Once we are clear on that, then
it becomes clear that {lo pavyseljirna} and {da poi pavyseljirna} refer
to the same thing, just like {lo gerku} and {da poi gerku} refer to
the same thing. Whether the thing they refer to is a real life beast
or a mythological character depends on the definition of
{pavyseljirna}.

Jorge