Re: On {lo} and existence

[ucleaar <ucleaar@ucl.ac.uk>]

Jorge:
> I have been supposing that predicates are independent of worlds.
> No, you haven't. In some world you accept that "x1 is a man" can be
> satisfied by something with three heads. That means that that predicate
> is not world independent. In one world, being a man does not exclude
> having three heads, and in another world it does. That makes the
> predicate world dependent.
> If you define the predicate by listing the things that satisfy it,
> then obviously it is world dependent. If you define it by listing the
> properties of the things that satisfy it, then again it is world
> dependent, because "having three heads" is allowed in one but not in
> the other.

I define the predicate in neither of these two ways. I define it in
terms of a set of necessary and sufficient conditions (suitably
enriched to account for prototype categories) for satisfying
it. These conditions are independent of worlds. Take an easy
example like "bachelor". There is in this world no bachelor with
three heads, but in any world, if X is male and unmarried then
X is a bachelor, whether or not X has 3 heads.

> > If I wanted to say "I told a story about a man (who may or may not
> > exist in this world)", I'd say {mi te cfika lo dahi nanmu}.
> I don't understand. If you predicate about something, that something
> either exists or doesn't exist in this world. If you say {mi te cfika
> da}, I can ask {xu da poi se te cfika do xanri}, and the answer should
> be either yes or no. It may be that you don't know the answer, but
> in predicate logic it is either true or false.

I agree. And if the answer was yes, then it would mean that search
this world as you may, you won't find the man I was telling a story
about.

> > If we accept that my attempt to uphold the view that {lo} does not
> > {da poi} will not win consensus, then {mi te cfika lo nanmu} will
> > be equivalent to {da poi dahinai nanmu zohu mi te cfika da}, which
> > says - to me - that the man exists in this world.
> Yes, only if it is true that {ro da poi nanmu cu zasti}. The man exists
> because being a man entails existing, i.e. it is part of the meaning
> of {nanmu}, nothing else.

I agree with this too. I do think that being a man entails existing.

> > > It is a matter of what do we accept as a nanmu. In English, we quite
> > > happily accept a character of fiction to be a man. We could do the
> > > same in Lojban, and then there would be no problem with {mi te cfika
> > > lo cibyselstedu nanmu noi nanmu}, but yes with {ro nanmu cu morsi}.
> > I quite happily accept that a character of fiction be a man *in that
> > fictional world* but not in this world.
> We are failing to communicate. The background world is the world where
> the utterance takes place. In that world, each predicate is supposedly
> well defined. I can talk *in this world*, i.e. in the world where I'm
> making the utterance, about fictional characters. When I say in English
> that Sherlock Holmes is a man, I am saying that of a character of fiction
> in this world.

We must also bring into consideration the world that determines the
truth of a proposition. If you say S.H. is a man, and you say it of
this world, then it's false. If you say it of the fictional world
then it's true. Either way, you and your utterance remain in this
world.

> I am not entering the fictional world where Sherlock
> really exists and becoming myself a fictional character in order to
> make the utterance. Thus, I am talking of something that satisfies
> *in this world* the predicate "...is a fictional character".

Right.

> Then, in English, the predicate man() can be satisfied *in this world*,
> by characters of fiction.

No.

> On the other hand, the same word has a
> different meaning *also in this world*, when I say "all men are
> mortal". This is because in English, like in any natlang I suppose,
> words don't have fixed meanings. In predicate calculus, we probably
> don't want to use the same word for several different predicates.
> In Lojban, I suppose we don't want that either. So nanmu() probably
> cannot be truthfully predicated of fictional characters.

It can, provided that the world against which the truth of the
predication is evaluated is the fictional world.

> Or maybe it can, in which case {ro nanmu cu morsi} is false.

Again, it depends which world it is said of.

> What I've been trying to
> get at is that for most predications to be true in universe X, their
> sumti must also exist in universe X. E.g.:
>
>  Real    Fictional
>  false   true         Sherlock Holmes solved many crimes.

Agreed that it is false, but not because there is no Sherlock Holmes,
since obviously there is. The name "Sherlock Holmes" has a well defined
referent, namely the fictional character that is a fictional character
in this world. It is false because it is false that characters of fiction
can solve real crimes. On the other hand, the predication "Sherlock Holmes
du Sherlock Holmes" is true, and so is "Sherlock Holmes is a character
of fiction".

> > while for a few predicates to be true in universe X, certain of their
> > sumti needn't exist in universe X. E.g.:
> >  Real    Fictional
> >  true    false        I mentioned Sherlock Holmes.
> Unless the utterance is produced in that fictional world, I don't see
> how can you evaluate its truth value there. Utterances only make sense
> in the world where they are produced. The sentence you wrote corresponds
> to two different utterances. It would seem to be a sentence that by
> simply uttering it, it becomes true, so if someone utters it in that
> fictional world, it is a true utterance.

The true-merely-by-being-uttered follows from {mi}. Change the example
to "A.R. mentioned S.H.".

I mean "A.R. mentioned S.H." to be a proposition rather than an
utterance. As you know, I do not believe utterances have truth-values.
Utterances are actions, like sneezing or kicking a football are.
This *proposition* is true as it applies to this world, and false
as it applies to the fictional world.

> > > My question is, is that a mlatu? Does it satisfy the predicate "mlatu"?
> > > If it does, then I have no problem to say you draw {lo mlatu}. If it
> > > doesn't, then you drew something else, perhaps {lo cibyselstedu mlatu}.
> > My answer is: Yes, it is a mlatu, and yes it satisfies the predicate
> > "mlatu", but that {da poi mlatu zohu mi te pixra da}, which
> > is equivalent to {da poi dahinai mlatu zohu mi te pixra da},
> > is false.
> Then it doesn't satisfy the predicate {mlatu}.

It does. It possesses all necessary properties for mlatuhood.

> {le se pixra cu mlatu} is false.

If evaluated against this world, yes.

> I don't care what the truth value of another utterance of the
> same sentence would be in some other world, because I'm speaking in this
> world, so I only know the meaning of words in this world. Utterances
> have truth values only in the world in which they are uttered.
> Sentences don't have truth values.

As I said above, utterances don't have truth values either. It is
the propositions they express that have truth values.

> > > > Or, put another way, it is possible for
> > > > the model to exist only in an imaginary world created by the picture.
> > > By "exist" here you don't mean logical E. The model, or subject, obviously
> > > has to exist (E) to satisfy {mi te pixra da}. Now, why would you
> > > call it a mlatu if it doesn't mlatu?
> > It does mlatu. But it is in the picture-world that it is a mlatu.
> But that doesn't make sense. The utterance is not produced in the
> picture-world.

That is not relevant.

> > In the world where I create the picture, it does not mlatu; it is
> > nought but a se pixra.
> And you are referring to it in this world, so it doesn't make any sense
> to say that in some world it does mlatu.

It doesn't matter which world I refer to it in.

> It would be equally informative
> (except for pragmatics) to say that in some other world it does gerku.

Well that would depend on the semantics of {pixra}, or some lujvo
made of it. It could be that {pixra lo mlatu} is to be interpreted
as claiming that in the world within the pixra there is a cat.

> You say that the meaning "time elapsed between two events" is
> independent of the universe. Ok, but it doesn't really matter,
> since all my utterances in this universe must refer to objects
> of this universe (real or imaginary ones, but of this universe).

I take "imaginary" and "not of this universe" to be the same.
I do not see any basis for distinguishing between them. I agree
that every utterance refers to objects that are real or imaginary;
I don't think it could be otherwise.

> > Another example: if we are told that Aragorn's eyes are blue
> > then it is legitimate for us to conclude that were we to behold his
> > eyes we should perceive their colour as blue.
> Right. The question is, how is {blanu} defined? Is it true that
> characters of fiction can be blue? Is it true that characters of
> fiction can have eyes?

Yes and no. The proposition "characters of fiction can have eyes"
is false of this world. The proposition "Aragorn has eyes" is
true of M.E. world.

> This has to do with the definition of {blanu} and {kanla}.

Only to the extent that these predicates, like most others, require
their sumti to be real.

> The gismu list also says that {citno} means both "young" and "short
> in elapsed duration". Those two are different meanings. "Young" only
> applies to living things, or by extension to things with an expected
> maximal duration. For example, I never understood whether we would
> use {citno zdani} for "new house", since houses don't really have
> expected durations, so we don't say that they are young.

I don't find a problem with {citno zdani}. In England I would say
that a house that is more than 300 years old is definitely old.
Therefore a house that is 10 years old is definitely young.

> Also, would we say that a short event is a {citno fasnu}, a "young
> event"? I don't think so. I think {citno} will only be used for
> living things or other things with "lifetimes".

I should think not either, but because youth has to do with elapsed
duration from the perspective of some temporal reference point,
rather than with total duration.

{citno fa le nu troci} makes sense: "the struggle is young", "the
struggle has only just begun". Example context: early in an
election campaign.

> > So if {nu}
> > is defined as something that is not necessarily manifest, while everything
> > else is defined as by default something that is manifest,
> Everything else? How about {crida}, {xanri}, {namcu}, etc?
> What do you mean by manifest?

Empirically discoverable. Something like that. That covers {crida}
(seek trolls under bridges, and fairies at the bottom of the
garden) and {xanri} (look inside the imaginer's head). {namcu},
I don't know about.

> > then there is
> > an inconsistency. I've given additional reasons for why {nu} is
> > inconsistent (its guaranteed non-emptiness, its unverifiability).
> It would be as verifiable as {xanri}.

No. {xanri} is "x2 imagines x1". Verify by inspecting x2's mind.

---
And