Subject: Re: [lojban] Set of answers encore

From: [email-masked]
Date: Mon, 1 Oct 2001 22:24:46 EDT

In a message dated 10/1/2001 7:17:57 PM Central Daylight Time, 
[email-masked] writes:

> >Why would "le du'u <bridi>" be different from "le broda"? If 'le'
> >always refers to the extension, then doesn't "le du'u <bridi>" refer
> >to the extension of "du'u <bridi>"?
> 
> Yes, but the extension of {du'u broda} preserves the intension
> of {broda}. {le broda} and {le brode}, for broda different than
> brode, can refer to the same extension, but {le du'u broda} will
> 

Well, sorta. Suppose that {brode} and {brode} refer to exactly the ame 
things in fact, "has a heart" and "has a liver," say (I'm sure la pier will 
tell me this examples is hopelessly out of date and it probably is, but 
suppose). The {ko'a broda} and {ko'a brode} will be true or fasle together 
for every referent of {ko'a}. That means that le du'u koa broda} and {le 
du'u ko'a brode} always have the same truth value, for a given referent of 
{ko'a}. And so theya re equivalent and interchangeable in any context where 
only the truth value matters. But there are contexts where the truth value 
is not all that matters: {mi jinvi...} for example. There you cannot 
exchange items with the same truth value and be sure to keep the truth value 
of the whole the same. Why not? The standard answer is that in those 
contexts (intensional contexts) the referent of the expression {le du'u ko'a 
broda} is no longer the basic referent, its truth value, but its regular 
sense -- roughly the rule by which one determines its truth value in a given 
world. Clearly, looking for a heart (pump in the blood system) is different 
from looking for a liver (filter in the blood system), so the rules are 
different and thus the two expressions are no longer interchangeable. The 
reason for this rule is that, without it, you get absurdities like moving 
from "Jim believes that 2+2 =4," to "Jim believes that Casaubon showed the 
Smargdarine Tables were a third century pseudograph" on the grounds that they 
are both true. The rule slows the errors down quite a bit. It is debatable 
whether this means that {du'u ko'a broda} has a different extension from 
{du'u ko'a brode} or whether it means that in some cases it is not the 
extension but the intension that counts (I find the latter easier to deal 
with).