On Wed, Dec 17, 2008 at 5:29 PM, Jorge Llambías
<jjllambias@gmail.com> wrote:
Here is a hopefully more clear restatement of the problem. Given {su'o
da na broda gi'e na brode}, we can rewrite it in purely prenex form as
follows:
su'o da zo'u ge na ku zo'u da broda gi na ku zo'u de broda
"There is some x which is neither broda nor brode."
Applying De Morgan's laws, we can move the negation through "ge",
changing it to "ga", and then through "su'o", changing it to "ro":
na ku ro da zo'u ga da broda gi da brode
"Not every x is broda or brode."
So far so good. I doubt anyone objecs to any of that. The original
"na"s can't be taken to have scope over "su'o" because "gi'e" will
block them.
Now let's consider just {su'o da na broda}. The obvious prenex
rewriting, if we hadn't read of any special rule, is:
That last sentence sets up an interesting straw man -- First, it uses a word, "obvious". Obvious to whom? To those who expect na to behave the same as naku? And why should that be true? "It's obvious, if I had never encountered a platypus or echidna, that all mammals are placental"
No generic statements about obviousness can be made with regard to lojban, especially if one encounters na as their first negation. Which, if you read the CLL through as your first exposure to lojban, as I did, is in fact what happens. The "naku" comes a whole chapter later. And how is it first encountered? By saying that a bridi that includes a na can be rewritten as a prenex with "naku" all the way on the left, and then proceeds to explain how to move it around etc. So to me, the use of "na" as described in CLL is natural, and the way want to rewrite it is unnatural.
su'o da zo'u na ku zo'u da broda
"There is some x which is not broda."
na ku ro da zo'u da broda
"Not every x is broda."
which pretty much would agree with the case with "gi'e".
But for some inexplicable reason, the official rule is that in this
case "na" jumps over "su'o" without changing it, and "su'o da na
broda" has to be read as "no x is a broda". The special scope rule
for "na" is not applicable in general, so why have it at all? Just to
make things complicated?
So it's not that the na "jumps the su'o". It's that na is defined that way, and naku is a special subcase of na that works quite differently. I'd've personally been a lot happier if they had created an entirely different cmavo for "naku" rather than modifying na in a way that is counterintuitive to the way it normally works (or the way things like tense+KU works, for example). If they had a completely different cmavo, I doubt we'd be having this argument.
--gejyspa