Subject: [lojban] Re: importing ro

From: Jordan DeLong <[email-masked]>
Date: Wed, 6 Nov 2002 09:49:52 -0600

On Wed, Nov 06, 2002 at 04:46:33PM +0200, Adam Raizen wrote:
> la .and. cusku di'e
> >The book is quite clear that ro as a quantifier is importing (16.8,
> >as pc has just pointed out on Jboske). Like you, my preference
> >would have been for nonimporting ro, but I can't see any grounds
> >for overriding the book -- it's not inconsistent or 'broken' on
> >this point. 
> 
> It sure is inconsistent on this point. According to the book, 'ro 
> pavyseljirna xirma cu blabi' is false, since 'ro pavyseljirna' has 
> existential import, and thus 'naku ro pavyseljirna xirma cu blabi' is 
> true, since it is the negation of a false statement. According to ch. 16 
> sec. 11, this is exactly equivalent to 'su'o pavyseljirna xirma naku 
> blabi', which is false, since once again it claims existence of 
> unicorns, and so either the book allows contradictions, and should be 
> called 'the complete zenban language', or we can disregard that 
> silliness about 'ro' having existential import, and use 'ro' as is 
> standard in mathematics at least (whether or not that is the standard 
> use in logic, as pc seems very certain that it is not).

"naku ro pavyseljirna cu blabi" is not a true statement, because
it makes more claims than you are giving it credit for, and you
only contradicted one of them. In fact, it's not even a true
statement with a nonimporting universal quantifier, if we keep our
negation boundary rules unchanged (more on this below).

The reason is that you're constructing your original statement
wrong. To work with an importing ro you have to do it by using a
nonrestricted variable when you don't want to claim something exists;
like this:

ro da zo'u ganai da pavyseljirna gi da blabi
Ax(Ux -> Wx)

Which is true even in a universe of discourse where there are no
unicorns. Though, it is false in the empty universe (not that we
care much about that).

It should be noted, btw, that:

no pavyseljirna cu blabi

is a false statement because no imports also, since it can be moved
around.

Actually the more I think about this the more I like importing
universals for lojban. Take a look at the generalization of what
you were talking about:

naku ro da poi gerku cu broda

Now; imagine that ro *doesn't* import. The above sentence, then,
can't have the negation boundary moved:

su'o da poi gerku naku broda

which claims there is at least one gerku.

So what's really going on is what AndR says here, I think: It is
"da" that imports, not ro. Which is both consistent with book and
makes sense (and i'm even starting to like it better than nonimporting
foo).

-- 
Jordan DeLong - [email-masked]
lu zo'o loi censa bakni cu terzba le zaltapla poi xagrai li'u
sei la mark. tuen. cusku