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Re: [ontolog-forum] Truth

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>, "Matthew West" <dr.matthew.west@xxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Wed, 25 Jul 2012 00:37:18 -0500
Message-id: <A8B6DDF7-D05D-4232-8A81-1EEE37B1E9B7@xxxxxxx>

On Jul 24, 2012, at 2:05 AM, Matthew West wrote:    (01)

> Dear Pat,
> I'm trying to get my head round this stuff.
> 
>> 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 things, a
>> context and a proposition:
> 
> MW: How is ist different from simple inference? i.e. from
> If c then p.    (02)

Several ways. First, c is not a sentence, but a context. It might be a time, 
for example, in which case ist(c, p) says that p is true at that time. Or it 
might be a fictional story, eg     (03)

ist(SherlockHolmesStories Inhabits(Dr.Watson 221b_Baker_street) )    (04)

or indeed, it could be a sentence, I guess. But then (this is the second point) 
the relationship between the context (even if it is a sentence) and the 
sentence in that context is not a simple Boolean relationship like ((not c) or 
p). It is probably not a function of their truth-values at all, in fact. It 
would be more like a modal relationship where the c part determines the 
particular modality.     (05)

But just to re-emphasise my point, above, I wasn't trying to get clear about 
the c part, but rather the apparently more obvious part, the p. It turned out 
that this had been miscategorized for over a decade in the development of 
context logics.     (06)

Pat    (07)


> Regards
> 
> Matthew West                            
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