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Re: [ontolog-forum] Truth

To: John F Sowa <sowa@xxxxxxxxxxx>
Cc: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Tue, 24 Jul 2012 23:45:57 -0500
Message-id: <4A527E95-C5B5-4A13-89F1-B2C3A7F57546@xxxxxxx>

On Jul 24, 2012, at 7:16 AM, John F Sowa wrote:    (01)

> Pat,
> I agree very strongly with these points, but I think they were
> discussed at a different meeting.  At the one I recall, McCarthy said
> that it was premature to standardize a theory of contexts.  He said
> that as we were leaving the comp. sci. building at Stanford.    (02)

He never disagreed with this position, AFAIK. JMcC's point was that there was 
no single "theory" of contexts; that contexts are not a natural kind, and a 
"context" is just anything that anyone cares to use in a context kind of a way, 
ie as something that influences triuhvalues and denotations. So to my (often 
repeated) objection that time, for example, and belief, for example, were very 
different kinds of thing and influenced truth in very different kinds of ways, 
so subsuming them under a common rubric of "kinds of context" was actually 
regressive rather than helpful, his response was always that the point of a 
context logic was not to capture the essence or nature of contexts, but rather 
to be simply a general framework for stating inferences which might be 
influenced by *any* kind of context.    (03)

>>> [The informal meeting in 2006] included John McCarthy, his student Selene
>>> Makarios (who was working on a theory of contexts), and Mike Genesereth.
> PH
>> And me. And it was then that I asked John about his basic logical construct
>> 'ist', written as ist(c, p) and read as meaning "p is true in the context c".
>> The question was, is the 'p' in this formula a sentence or a proposition?
>> It is *written* in the McCarthy/Guha/Makarios context logics as a sentence;
>> but to my delight, John said it was a proposition. Which is exactly what
>> it is in the IKL way of writing this as a logical relation between two 
>> a context and a proposition:  (ist c (that p))
> I prefer the IKL method, because it enables the two operators to be
> used independently.  "(that p)" is a kind of quasi-quotation that
> allows variables in p to be bound to quantifiers outside of p.    (04)

Hmm, I don't think it is correct to think of it as quasi-quotation. Rather than 
quoting the sentence, it treates it as defining a zero-ary predicate, and 
creates a term denoting that entity.    (05)

Pat    (06)

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