Message-Id: <m0tI1a2-0000ZUC@xiron.pc.helsinki.fi>
Date:         Tue, 21 Nov 1995 17:30:40 -0500
Reply-To:     Jorge Llambias <jorge@PHYAST.PITT.EDU>
Sender:       Lojban list <LOJBAN@CUVMB.BITNET>
From:         Jorge Llambias <jorge@PHYAST.PITT.EDU>
Subject:      Re: jei
To:           Veijo Vilva <veion@XIRON.PC.HELSINKI.FI>
Content-Length: 2683
Lines: 64

la djan cusku di'e

> There is a kind of implicit "du'u" underlying "jei", which is the truth
> value of the proposition that <bridi>.  To say you know the truth value of
> a proposition is indeed the same as knowing whether it is true or false.

We are playing with the idiomaticity of English here. "I know the
truth value of that proposition" means the same thing as "I know
what is the truth value of that proposition". I have no argument with
that, of course. But "the truth value of that proposition" in the first
sentence is not the same argument that appears in "the truth value
of that proposition is 1".

English allows you to omit the "what is" from the indirect question, but
that doesn't mean that the logic of the sentence changes.

{jei} can't have both meanings. If it means "whether", then it can
be used to translate

(1a)    I know whether that is true.
(1b)    I know what is the truth value of that.
(1c)    I know the truth value of that.

But in that case, it cannot be used to translate

(2)     the truth value of that is 1.

(1a), (1b) and (1c) all mean the same thing. (1c) is just an idiomatic
variation of (1b). (1c) does not map to a predicate know(I,t) where
the second argument is the same value as the first argument in (2).

So, {jei} either means "x1 is the truth value of <bridi>", or it is
a compact form of an indirect question, but it can't be both.
According to the ma'oste it is the first. According to usage it is
the second. I recommend avoiding it altogether, since it is not
needed much. For the indirect question it is better to use {du'u xukau}.

Lojbab:
> If I understand you, then you do not like jei for "whether" because
> if the truth value of broda is, say 1.0, then to say
> "mi djuno le jei broda" means "I know the number 1".

More or less. But "I know the number 1" is meaningful in English,
because "know" accepts things other than propositions as objects,
while {mi djuno li pa} is utter nonsense, because {li pa} is not
a proposition. I know that the number one about what?

> If I understand this correctly, then I agree.  You should properly say
> "mi djuno ledu'u li xokau cu jei broda",

I would agree with that given the current definition of {jei}, but
notice that usage has been totally different. {jei} has not been used
according to its prescribed definition at all.

> which I would likely abbreviate
> as "mi djuno tu'a lejei broda" or "mi djuno fi lejei broda".

The one with {tu'a} is not really an abbreviation of your first sentence,
because there you had {jei} as a selbri, not as a sumti, but I agree that
it may work as well, as an abbreviation of:

        mi djuno le du'u le jei broda kei mokau

Jorge