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Re: [ontolog-forum] Ontology, Information Models and the 'Real World': C

To: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Waclaw Kusnierczyk <Waclaw.Marcin.Kusnierczyk@xxxxxxxxxxx>
Date: Thu, 31 May 2007 19:19:08 +0200
Message-id: <465F038C.5030802@xxxxxxxxxxx>
Ingvar Johansson wrote:
> Waclaw Kusnierczyk schrieb:
>> I think we agree.  A context, as treated in IKL, corresponds to a 
>> perspective (no cognitive agent implied) on a proposition *as if it 
>> were* true or false, irrespectively of whether it *is* true or false.
> Dear Waclaw,
> Does this solve the following earlier problem of yours: "The question, 
> again, is about propositions. The sentence "no roses are blue" was true 
> some time ago, and is false now; but does it correspond to the same 
> proposition in both cases? Is it the proposition that changed its truth 
> value, or are we really dealing with two distinct propositions: 'no 
> roses are blue at t1', and 'no roses are blue at t2'?" ?    (01)

I am not sure what it is that you point to as *this* that would solve my 
problem.    (02)

What I have learned is this:    (03)

- propositions are eternal, and they are either eternally true, or 
eternally false -- in that sense of 'eternal' which refers to the whole 
history of a single world;    (04)

- in various contexts, propositions may be regarded false or true, 
irrespectively of their eternal truth value (*the* truth value);  this 
'regard' reflect the perspective on the world taken by the context, a 
hypothesis about the world, a possible scenario, etc.;    (05)

But I am still confused in this issue, in the sense that I do not see a 
clear, coherent view being discussed here.  I am somewhat skeptical 
about the 'we come to an agreement'.  I have had my own favourite, 
appearing to be coherent to me, view on propositions, but it does not 
seem to be fully compatible with any of those presented here by others.
Which does not matter much for you, I guess.  I think I understand Pat's 
view;  I need to think it over and possibly come back with further silly 
nagging.    (06)

Does that answer *your* question?  If not, you may need to restate it.    (07)

> If "no roses are blue" are stated twice (in the way you have described) 
> *in the same context*, then it seems to me that a distinction such as 
> mine between *sentence meaning* and *used sentence meanings* is 
> nonetheless needed as a complement.    (08)

If the sentence "no roses are blue" is read as 'no roses are blue now' 
twice, then it corresponds to two distinct propositions;  one of them, 
say, is 'no roses are blue at t1' and is (eternally) true, the other is, 
say, 'no roses are blue at t2' and is (eternally) false.    (09)

If the sentence "no roses are blue" is read as 'no roses are ever blue' 
twice, then it corresponds twice to the same proposition;  this 
proposition is either eternally true or eternally false, and if there 
were, are, or will be blue roses at any time whatsoever, the proposition 
is false, irrespectively of there not being or not having been any blue 
roses at some particular when the sentence is interpreted.    (010)

When it comes to multiple possible worlds, I agree to the view that a 
proposition may be false in one world, but true in another, provided 
that it actually means:    (011)

- that only one of those many worlds is the actual one, and that the 
proposition is either true or false, immutably, in that world, and    (012)

- that those other worlds are either just hypothetical scenarios of how 
the actual world could have been or could be -- and thus we talk about 
how the proposition *could have been* or *could be* if those scenarios 
have happend or would happen -- or    (013)

- that those multiple worlds are all actual worlds, but as such they are 
distinct and unreachable from each other, and in this case it does not 
seem sensical to speak about *the same* proposition, even if there is an 
isomorphism between the worlds which would allow a sort of cross-world 
identity.    (014)

If this does not make sense to you (which I believe is quite possible), 
I won't come, I am afraid, with a much better version.    (015)

I think your 'sentence meaning' and 'used sentence meaning' could be 
somehow attached here, but I am not sure how (and if), and I am not very 
much convinced it is necessary.    (016)

vQ    (017)

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