Subject: [lojban] Re: importing ro

From: Adam Raizen <[email-masked]>
Date: Wed, 06 Nov 2002 20:22:16 +0200

la djorden. 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).

"naku ro pavyseljirna xirma cu blabi" is the negation of "ro 
pavyseljirna xirma cu blabi", and so one of them must be true and the 
other false; that is simply the definition of negation. If ro has 
existential import, as the book seems to claim at first glance, then "ro 
pavyseljirna xirma cu blabi" is false, and its negation is true. This is 
not just Logic, but also what CLL says (15.2): "The most important rule 
about bridi negation is that if a bridi is true, its negation is false, 
and vice versa." [twice, a few paragraphs apart] (bridi negation is 
demonstrated to be putting 'na' in front of the selbri, which is 
elsewhere explained to be equivalent to putting 'naku' before the whole 
bridi.)

> It should be noted, btw, that:
> 
> no pavyseljirna cu blabi
> 
> is a false statement because no imports also, since it can be moved
> around.

If it is indeed false, then either 'su'o pavyseljirna' is not importing 
(probably not the best option), or 'no pavyseljirna' != 'naku su'o 
pavyseljirna', which is extremely counterintuitive, no matter how 
intuitive an importing ro might be.

> 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.

If ro doesn't import, then your first sentence would use an importing 
"not all", since with the empty set for the set of gerku the sentence 
without "naku" is vacuously true, and thus its negation would be false. 
Therefore, there is no problem with equating that with the second 
sentence; both are importing.

> 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).

It can be made consistent, but then we would have to drop the ability to 
move negation across quantifiers while switching the quantifier, which 
is also inconsistent with the book.

mu'o mi'e .adam.