John F. Sowa schrieb:
> Wacek and Ingvar,
>
> It happens that English has no tenseless verb forms.
> In predicate calculus, you could write:
>
> ~(Ex)(rose(x) & blue(x)).
>
> This statement has no reference to any time or place.
> In English, it is possible to make a statement without
> reference to place, but not to time.
> (01)
And isn't this the reason why Quine introduced his notion of 'eternal
sentence'? And propositions expressed by eternal sentences cannot change
truth-values, can they? (02)
> vQ> 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?
>
> I would like to express the proposition stated by the
> above formula in predicate calculus. That statement
> is independent of any time, place, or context. The
> proposition it states has no unbound variables that
> could be bound, explicitly or implicitly, to any context.
>
> Yet that proposition can have different truth values
> in different contexts despite the fact that its meaning
> does not change.
> (03)
Are you denying the old truth: 'same meaning, same reference'? To me,
this truth implies 'same proposition, same aboutness', which you are
denying. (04)
best,
Ingvar (05)
> IJ> I would say that there is only one *sentence meaning*
> > "no roses are blue", but two *used sentence meanings* and
> > two propositions, one which is true and one which is false.
> > Propositions cannot change truth-values.
>
> I would identify 'sentence meaning' with 'proposition'.
> Then you could apply the word 'used' to either one, if you
> like. I wouldn't say that propositions or sentence meanings
> change -- they just represent configurations of individuals,
> properties, and relations, real or hypothetical. But they
> can be used for different purposes.
>
> vQ> Note that I do not argue for this or other theory of
> > propositions; I am just curious, and it seems to be
> > an issue that should not be just neglected (e.g., for
> > the purpose of precise documentation of IKL, a very
> > practical task).
>
> Since IKL (like predicate calculus and conceptual graphs) has
> no default tenses, it has no implicit context dependencies.
>
> vQ> As above; if a proposition is fixed to a fact, it cannot
> > be refixed to another fact -- or would this be what you suggest?
> > If the fact is (was) that Osama slept at t1, the proposition
> > that Osama slept at t1 was true, remains true, and will always
> > be true.
>
> That raises some important questions:
>
> 1. What is a fact?
>
> 2. What are the references in a proposition bound to?
> To individuals in a particular fact? To individuals
> independent of any specific fact? Or to configurations
> of individuals, which may be considered independently
> of any specific binding?
>
> I would claim that facts (at least facts about the world,
> not facts such as 2+2=4) are bound to specific chunks of
> space-time.
>
> But I would say that propositions are abstractions about
> configurations, which could characterize different facts in
> different contexts. If a proposition names an individual,
> such as Osama or Bob, it is not necessarily bound to a
> particular fact in which that individual participates.
>
> For example, you might ask "How often did Bob wake up last night?"
> To answer that question, I would consider the proposition that
> Bob wakes up and try to determine how many times the corresponding
> configuration was a correct characterization. (Perhaps Bob fell
> asleep in front of his web cam, which was on for the whole night.)
> I could answer that by checking each event in the record for which
> the configuration of Bob waking up occurred.
>
> An interpretation of that kind is required to support hypothetical
> statements, which may refer to actual individuals. For example:
>
> If Gerald Ford had been elected president in 1976,
> Ronald Reagan would not have been elected president in 1980.
>
> That counterfactual statement refers to actual individuals and
> possible outcomes of actual events. Both of the propositions
> in the antecedent and the consequent could be translated to
> different languages while retaining the same meaning, but there
> are no facts to which either of the propositions could be bound.
>
> This interpretation is consistent with the claim that a proposition
> represents an abstract configuration, which might include references
> to actual individuals independent of any specific facts in which
> those individuals participate.
>
> John
>
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> (06)
--
Ingvar Johansson
IFOMIS, Saarland University
home site: http://ifomis.org/
personal home site:
http://hem.passagen.se/ijohansson/index.html (07)
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