>John F. Sowa wrote:
>> Ingvar,
>>
>> My position and Pat's position are compatible and for the same
>> reasons: we both have propositions, but we admit that their
>> truth values in different contexts can be different.
>
>One could call it 'hard-headed language puristness', but it seems to me
>that Ingvar makes a valid point (if I understand him correctly); to me,
>to say (as Pat did) that a proposition has a fixed truth value, which is
>not a function of anything (or is a nullary function), and then to say
>(as Pat did) that a proposition may have different truth values in
>different contexts is plainly confusing. (01)
What I said is that propositions have fixed
truthvalues, and that propositions may also stand
in relations to other entities. One of these
relations is conventionally denoted by "ist",
holds between entities called 'contexts' and
propositions, and is understood - externally to
the actual logic - to have the interpretation
that the proposition is 'true in the context'.
This relationship of truth-in-a-context has
absolutely no relationship with actual logical
truth, and is indicated in the formalism simply
by the ist relation: that is, we say that P is
'true in C' simply to mean that "ist(C, P)" is
logically true. Now, perhaps calling this 'having
a different truth-value in a context' is
confusing, since this truth-in-a-context is not
really anything to do with actual truth-values:
but it is simply an extension of the conventional
nomenclature. So if you find this awkward,
abandon this terminology and say instead that P
is C-true, or something similar, which draws
attention to the fact (and it is a fact, even in
a context logic) that truth and C-truth are
different; and the the latter has a parameter. (02)
>
>While in the case of multiple possible worlds -- which seem a purely
>theoretic device that does not reflect the actual reality we live in --
>it does sound reasonable to say that a proposition may have different
>truth values in different worlds, as far as the worlds are truly
>different possible worlds, rather than consequtive stages of the same
>actual world (in which case we would have to admit that the truth of a
>proposition is time-dependent). But it does not seem to me reasonable
>to say that a proposition may have different truth values in different
>contexts in the same actual world (03)
My position is that I have no idea what a
'context' is supposed to be (and I have spent
more mental hours than I want to admit trying
find out what others mean by this horribly
evasive word) and I prefer to do without them
altogether. There simply is no fact of any matter
involving the term "context". But if someone
wishes to speak of truth in a context - and many
people do - and has some notion of what a context
might be (and people do use it to mean possible
worlds, by the way, among many other kinds of
thing), then the IKL stance and formalism
provides them with the ability to formalize their
intuitions by writing axioms about some suitable
relation between their kind of context and
propositions. In other words, contexts are hereby
brought into the scope of ontological
engineering, rather than being some mysterious
aspect of truth itself that we must resolve
before we can even get started. (04)
>-- especially after having said it has
>a fixed truth value. It may be that a context considers, in any sense
>you like, a proposition to be true or false, independently of its actual
>truth or falsity, but the proposition does not thereby change its truth
>value. We end up saying that a proposition is true, but (and?) false in
>some context, for example. Awkward, as Ken says. (05)
If you think this is awkward (and I agree) then I
suggest you would be better off without having
contexts at all. It is part of the very idea of
contexts that they can change the meanings of
things, so that sentences may be true but seem
false in a context, or vice versa. They are
inherently <it>de dicto</it>, inherently opaque,
inherently elusive. Awkward, I agree, but
awkwardness is inevitable when one sets out to
write axioms (which are by their nature intended
to be effectively eternal, or at the least
long-lived) about such truth-shifting entities as
contexts. (06)
Pat (07)
>
>vQ
>
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