Re: Contexts and quantifiers in KIFsowa <email@example.com>
Date: Fri, 9 Apr 93 23:21:11 EDT
From: sowa <firstname.lastname@example.org>
To: email@example.com, interlingua@ISI.EDU, firstname.lastname@example.org,
Subject: Re: Contexts and quantifiers in KIF
There are a number of issues in your note that indicate a major
difference in how we would relate formalisms to the world, although
I don't believe it would change the way that we would use to formalisms
computationally. Following are some comments on your comments:
> 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.
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and Attitudes, MIT Press, 1983) is a bit out of date as a description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.
> Secondly, the fact that Tarski restricted the scope of his original paper to
> formalized languages is not particularly telling in this context. The purpose
> of his paper was to demonstrate an approach to semantics, and he succeeded
> for a broad class of formal languages. What he did not do in that paper was
> demonstrate that the same approach could be applied to natural languages.
Again, I completely agree with this statement. But I begin to disagree
with the following:
> But he also did not say that the approach could not be applied to natural
> languages. Indeed applied logicians and philosophers have applied the
> approach successfully to significant subsets of natural language.
My only disagreement is with the word "successfully". The primary
example of the application of Tarski-style semantics to natural
language is the work of Richard Montague and his followers. I have
a great deal of respect for that work, but I believe that the approach
is fundamentally flawed, for many of the same kinds of reasons that
Barwise & Perry give for situation semantics.
> The work
> we have done on the SUMM shows that the approach works for that subset of
> natural language that is captured in information systems of the kind that
> can be captured by EXPRESS, NIAM, ER, etc. So the issue is not whether the
> information is initially expressed in a formalized language, but the
> communicants can agree that a formalization captures the essence of what
> they are communicating with sufficient accuracy.
I agree that the Tarski-style of semantics works quite well for a
broad range of formal languages, among which I would include NIAM,
ER, EXPRESS, KIF, and even the version of CGs that we are mapping
to KIF. My reservations about its adequacy as a foundation for
natural language semantics, especially in Montague's formulation,
should not be considered as a rejection of its use for defining the
semantics of formal languages. That's what Tarski designed it for,
and it is still the best approach available for such systems.