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Re: [ontolog-forum] Truth

To: Pat Hayes <phayes@xxxxxxx>
Cc: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: John F Sowa <sowa@xxxxxxxxxxx>
Date: Tue, 24 Jul 2012 08:16:11 -0400
Message-id: <500E920B.1040701@xxxxxxxxxxx>
Pat,    (01)

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)

>> [The informal meeting in 2006] included John McCarthy, his student Selene
>> Makarios (who was working on a theory of contexts), and Mike Genesereth.    (03)

> 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?    (04)

> 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:  (ist c (that p))    (05)

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.    (06)

The option of saying that (that p) is true should be separate, since
there are many other things one might want to say about a proposition.    (07)

> BTW, JMcC also had a clear answer to the question, what is a context,  
> Which was, anything that you can write in the first argument position of an
> atomic ist sentence. That is, anything can be considered to be a context.    (08)

> The key point about the 'that' operator is, that it obviates the need to make
> any fundamental change to the underlying logic. The basic logic of IKL is
> simply first-order reasoning of the very same kind that has been used since
> Peirce and Russell. Contrary to what JMcC and his students have claimed,
> one does not need a context logic in order to logically formalize contexts.    (09)

>>  There are many different ways of axiomatizing how you would use the
>> 'that' operator to support a theory of context.    (010)

> Yes, exactly. For a lot more on this topic, see
> http://www.ihmc.us/users/phayes/IKL/GUIDE/GUIDE.html#ContextsModalities    (011)

And following is my paper for the AAAI Fall Symposium on Contexts,
which was held at MIT in 1995:    (012)

    Syntax, Semantics, and Pragmatics of Contexts    (013)

You, John, and I were at that conference.  At dinner, John successfully
got Ed Fredkin to pick up the tab.  As I recall, you and I happened
to go to the restroom at that moment and you remarked on the cost.    (014)

John    (015)

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