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On Sat, Nov 09, 2002 at 10:29:53PM -0000, And Rosta wrote:
> > On Sat, Nov 09, 2002 at 07:23:04PM -0000, And Rosta wrote:
> > > Here's why I had preferred nonimporting ro:
> > > First, I wanted to be able to say {ro pavyseljirna cu blabi} without
> > > having to claim that you can go out and find unicorns, and without
> > > having to rephrase to {ro da ga na pavyseljirna gi blabi}
> >
> > Why would you want to say that? Since there's no unicorns, any
> > statement about all of them is pretty boring. I can say {ro
> > pavyseljirna cu xekri} and be correct also
>
> Not according to my beliefs. I believe that all unicorns are white
> and some, but not all, are male.
But there are no unicorns... It's equally true that they're all
green with purple dots, whatever you may believe.
[...]
> > > Second, I wanted De Morgan to work. De Morgan with importing ro
> > > fails precsisely when the quantified set is empty
> >
> > That is pretty lame. I don't think we want naku rules to "sometimes
> > work"
>
> Why not? The occasions when they do work would be those that I expect
> would include all actual usage. The rules themselves would be
> principled and consistent. The only objection to the rules would be
> if they made us say what we didn't mean, or forced us to paraphrase
> to avoid saying what we didn't mean, but afaics this wouldn't happen.
The rules would not be consistent; that's the whole reason to fix
ro... See below.
[...]
> > If not there's nothing to prevent you from claiming {lu'a pi PA
> > lo'i pavyseljirna cu broda} for any PA or any broda, and being
> > perfectly correct
>
> Not by any sensical epistemology I can think of. Every claim is
> true or false of a given world. Give me a set of truth conditions
> and a world, and I'll tell you whether the claim is true of
> that world or not.
With non importing universals, you can universally claim anything
in the empty universe, and it's all true.
However, regardless of whether universals import, you can universally
claim anything about things which don't exist in any universe,
provided that the universe is nonempty if you use a importing
universal quantifier, and it is true:
Ax((Fx & ~Fx) -> Gx)
is true for any universe, and any predicates F and G. (A false
proposition implies all propositions -- we know Unicorn(x) is going
to be false in this universe, just like we know Fx & ~Fx is always
false, so we can infer anything from it, such as white(x), purple(x)...)
I dunno whether this qualifies as a sensical epistemology for you
or not, but it does for me.
[...]
> > There's another more sinister problem with this: it makes *all*
> > universal claims false. Because for anything of the form where in
> > this world Ax(Gx -> Fx), we can make another state of afairs where
> > there's another Gx which isn't Fx. If you want Ax to iterate over
> > the possible values which aren't even in the current universe, I
> > think it's more destructive to the logical system than our inconsistency
> > with De Morgan
>
> Read what I've said above & see if you still think this.
>
> Your comments above and below all make much more sense to me if
> you weren't aware of the convention of the implicit world-indicator.
Yeah; I misunderstood what you were suggesting. I thought you were
suggesting that Ax should cause x to be evaluated for all the values
in *all* worlds.
So, now that I understand what you're saying (I think): I think it
is entirely beside the point. Yes, in some universes we can say
ro pavyseljirna with import, or su'o pavyseljirna and be making
true statements. But I think you're trying to skirt around the
issue again, instead of addressing the real point: in a world with
*no* unicorns, what is the truth value of {ro pavyseljirna cu broda},
and what is the truth value of {naku ro pavyseljirna cu broda}.
Hopefully one is true and one is false ;)
I am not opposed to the implied world foo you bring up, I just think
it is entirely beside the point.
[...]
> > > The fact that we want to say true things about {su'o pavyseljirna}
> > > means that nonimporting ro wouldn't make our problems go away
> >
> > I don't think we want to say such things except when lying (which
> > is a perfectly legitimate application of the language)
>
> I'm not sure whether you really mean this, or it is just a rhetorical
> flourish, but if you mean it, then the response is that Lojban must
> be open to multiple metaphysicses. Not only is it not our job to
> dictate to others a correct metaphysics; we are also pledged to
> try to avoid building metaphysical constraints into the language.
> I'm sure Lojbab and xod would back me up on this, so it's not some
> kind of jboscological perversion I'm espousing here.
I'm not sure if I follow this part -- what's wrong with lying? I
would also say there's nothing wrong with someone saying {su'o
pavyseljirna} and refering to this world if they *believe* that
there *are* unicorns.... But if they believe that there aren't
any, they should/would stick to {ro} or a generic unless deliberately
decieving the listener.
(For the record it was mostly a rhetorical thing, but I imagine I
also "mean" it, whatever that means).
mu'o
--
Jordan DeLong - fracture@hidden.email
lu zo'o loi censa bakni cu terzba le zaltapla poi xagrai li'u
sei la mark. tuen. cusku
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