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Re: summary of reification semantics issues (material for discussion).

From: pat hayes <phayes@ai.uwf.edu>
Date: Fri, 14 Mar 2003 11:44:33 -0600
Message-Id: <p05111b09ba97c18f31c8@[]>
To: Seth Russell <seth@robustai.net>
Cc: www-rdf-comments <www-rdf-comments@w3.org>

>You say:
>One objection to the de re interpretation is that it does not allow
>for the adequate representation of propositional attitudes such as
>belief. This is controversial (see the discussion of the Russellian
>theory in http://plato.stanford.edu/entries/prop-attitude-reports/) ,
>but in any case there is ample experience which suggests that the de
>dicto interpretation would produce other problems with the
>representation of such ideas, and that an fully adequate
>representation of propositional attitudes is unobtainable using
>reification alone.
>The only problem I know of for the de re interpertation of the 
>reification syntax is that you can't substitute equivalents.

With de re semantics, you CAN substitute equivalents. The problem 
which arises with propositional attitudes is that such substitution 
produces unintuitive results (arguably) when it is done using an 
equivalence outside the propositional attitude report but applies it 
inside (as in the Superman example). The only adequate way to handle 
this is to have a mechanism for keeping track of the scope 
distinctions between propositions asserted inside and outside such 
attitude reports, eg distinguishing

s=k  and  P(s)  --->   P(k)


s=k and LL believes[....P(s)...]  --/--> LL believes[....P(k)...]


LL believes[.... s=k and P(s)...]  ---> LL believes[....P(k)...]

>It seems to me that the solution of that would be to come up with a 
>property for equating URIRefs that would exclude substitutions into 
>reification triples.  In other words, why throw out propositional 
>attitudes, why not just fix the semantics of equivalence ?

Because the semantics of equivalence is very basic, and doesnt need 
fixing. Equivalence just means two names denote the same thing. If 
they are the same thing, then obviously they have the same 
properties. The problem arises because when reading prop-attitude 
claims we often read them as saying that *the person with the 
attitude* would agree with this if it were presented to them *in this 
form*, and the basic problem is that this conflates issues of what 
the facts ARE with issues of HOW the facts are SAID. That is why the 
middle entailment is considered to be incorrect, not because LL 
doesn't believe that this actual guy, Superman=Kent, is strong - she 
does, as a matter of fact - but because if you were to ask her, is 
Kent strong? she would say 'no'. Thats because she doesnt know who 
Kent actually is, of course; but the last thing we want is for our 
basic logic to get as confused as Lois is about the way things really 

>If it is too late to fix dmal:equivalentTo, then invent a OWL 
>property that would exclude sustititions in reifications.

That amounts to adopting the de dicto interpretation. What is the 
justification for not allowing substitutions if those substitutions 
are in fact valid?

>What (if any)  are the other problems with propositional attitudes 
>exclusive of this one?

See above.


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Received on Friday, 14 March 2003 12:44:18 UTC

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