Re: Contexts and quantifiers in KIF (Chris Menzel)
From: (Chris Menzel)
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Subject: Re: Contexts and quantifiers in KIF
To: (sowa)
Date: Sat, 10 Apr 1993 01:18:22 -0500 (CDT)
Cc:, interlingua@ISI.EDU,, (Jim Fulton)
In-reply-to: <> from "sowa" at Apr 9, 93 11:21:11 pm
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Hi John, 

Jim writes:

: > The SITUATION construct you discussed adding to your TARGET
: > language, not your 
: > METALANGUAGE, is a MODAL construct.  It is formally intensional in
: > that it (or 
: > constructs like it) resist quantification across the construct and
: > they resist 
: > replacement of identicals or equivalences.  Moreover, if the word 
: > 'situation' 
: > is taken literally, it appears so similar in meaning to Kripkean "possible 
: > worlds" that the differences appear to be quibbles.  

And you respond:

: I agree with your statement up to the word "moreover".  I am using
: the term "situation" in a way that is consistent with situation semantics
: and the AI use in situation calculus (although the term "consistent"
: may be a bit too strong, since there are many variations of both those
: approaches that are not consistent among themselves or with each other).
: The basic point is that a situation is limited to a specified duration
: and extent of space-time, unlike the possible worlds of Montague and
: Kripke, which have no bounds.  The book by Barwise & Perry (Situations
: and Attitudes, MIT Press, 1983) is a bit out of date as a description
: of situation semantics, but its introductory chapters are a good
: statement of why they prefer finite situations to the open-ended
: possible worlds as a basis for semantics.

It is probably best not to make the distinction between worlds and
situations come down to finite vs. infinite, or closed vs. open-ended,
for several reasons.  First, situations themselves, in some
presentations of situation theory, can be infinite and open-ended in a
certain sense.  For instance, consider the situation occurring in your
office from noon to 1:00 pm today, and consider the basic facts or
"infons" (to use situation theoretic jargon) true in that situation.
There are all sorts of facts about you, for example, that are
supported in that situation.  In fact, for any bunch of facts about
you that you could come up with, we could probably think of more;
facts about the individual hairs on your head, say, or fibers in your
suit, or the propositions you considered, and so on and so on.  The
point, of course, is that just because that situation was bounded in
time and space doesn't mean there aren't cogent senses in which it was
infinite and unbounded.  By the same token, there are accounts of
worlds in which they can be as spatially and temporally bounded as
situations.  On David Lewis's view, for instance, there's a world that
consists of nothing more than, say, a coffee cup that springs into
being for 30 minutes and then ceases to exist just as abruptly.  And
for philosophers like Plantinga, Adams, Chisholm, Pollock, Fine,
possible worlds are abstract entities that do not exist in space and
(perhaps) time, and so the notion of spatio-temporal boundaries don't
have much purchase.  In the only other relevant measure of size--the
number of "facts" they make true--they now look a lot like situations.

A more cogent dividing line between situations and worlds, then, is
not finite vs. infinite but rather partiality vs. totality:
situations, unlike worlds, do not in general decide every issue.  The
situation in your office, for example (I assume, unless you're better
connected than I think), does not decide whether or not Boris Yeltsin
has a scar on his left knee; it contains no information that either
entails this issue or its negation.  A possible world, by contrast,
decides every issue; in every world either Yeltsin has such a scar or
(assuming he exists) he doesn't.  But note also: the distinction
between worlds and situations is not necessarily an intrinsic one; in
the "natural model" of a common version of current situation theory
(formulated by Barwise and Etchemendy) situations form a type of
lattice: and maximal nodes in the lattice are nothing other than total
situations, i.e., situations that decide every issue, i.e., possible
worlds.  So even though situation theory gives us good reason to add
"partial" situations to our semantical ontology, they are not any
different in kind from full blown, total possible worlds; worlds still
creep back into the theory as limiting cases.  So they are not
dispensed with quite as easily as you suggest.

For more up-to-date accounts of situation theory than Situations and
Attitudes, I'd recommend Barwise's collection of very nice essays The
Situation in Logic (CSLI Publications), Keith Devlin's informal and
enjoyable Logic and Information (Cambridge), and volume 1 of Situation
Theory and Its Applications (CSLI Publications).



Chris Menzel			    Internet ->
Philosophy, Texas A&M University    Phone ---->   (409) 845-8764
College Station, TX  77843-4237	    Fax ------>   (409) 845-0458