W3C home > Mailing lists > Public > www-rdf-logic@w3.org > June 2001

Re: Why? Re: rdf as a base for other languages

From: pat hayes <phayes@ai.uwf.edu>
Date: Fri, 1 Jun 2001 17:20:21 -0500
Message-Id: <v04210115b73dc1a74deb@[]>
To: las@olin.edu
Cc: www-rdf-logic@w3.org
>Jonathan Borden wrote:
> > Sandro Hawke wrote:
> > >
> > > For example, here are 7 facts:
> > >   1.  I can imagine a condition, X.
> > >   2.  X can be expressed accurately as English sentence Y.
> > >   3.  Y has four words.
> > >   4.  The first word of Y is "the".
> > >   5.  The second word of Y is "sun".
> > >   6.  The third word of Y is "is".
> > >   7.  The fourth word of Y is "shining".
> > ...
> > > Do you have any problem with this approach, beyond style?
> >
> > My problem with this approach is this:
> >
> > In order to decide the truth of any statement "X" I cannot simply test
> > whether it is or is not a direct member of the set of Statements. If it is
> > not a member, "X" might still be true, because it is inferred 
>from the other
> > statements as you describe.
>This is essentially always true, unless you forbid inference and close the set
>of sentences you're considering.  What's important is what we (minimally)
>require that you be able to tell/infer and what we (maximally) permit you to
>infer and what we do about any discrepancy that (almost inevitably) remains
>between the two.

I don't see there being anything here to do with permissions or 
requirements. How can one website emit such constraints on another 
web agent's actions? There arent any guards here.

> > So why say that statements are true just because they are members of this
> > set? ...
> > To me, stating that each statement in Statements is a fact does not gain me
> > anything (in ease of inferencing) and costs me alot (of cumbersomeness and
> > confusion).
>Well, not "are true" and not "is a fact", but "is asserted by the 
>document", at
>least, which may be the same as far as your concern goes.

No, no. That is what "assert" MEANS.

Look, if I assert (note: *assert*) the following sentence: "The sun 
is shining.", then while of course you are free to believe or 
disbelieve me, or indeed to draw all sorts of conclusions about me, 
it remains the case that what I said was that the sun was shining. 
That is not a sentence, but a claim about the way the world is: it is 
such as to make the sentence (that I asserted) true. You may observe 
me and correctly say "Pat asserted: "The sun was shining" " , much in 
the way that you might observe a frog and correctly say: "The frog 
said: "Graaak" ", but that observation does not constitute an 
exchange of content, and what you have asserted is not what I said. 
If we are having a conversation under normal rules of mutual 
cooperative communication, then a basic act of communication has 
taken place not when you make an observation about my utterance, but 
when you interpret the *content* of that utterance and accept it, ie 
when my asserting "the sun is shining" leads you to believe that the 
sun is indeed shining. I presume that the basic idea of RDF (and DAML 
and OIL, etc.) is that they are primarily intended to be used to 
convey content in roughly this way, though of course greatly 
simplified since it occurs between mechanical rather than human 
agents. The wide world being what it is, no doubt issues of trust and 
cynicism may well arise, but these surely are intended to be 
concerned with the *content* of what the RDF (etc.) is encoding, not 
about its *form*. If the primary goal of all this effort is just to 
enable one agent to send some symbolic shapes to another to enable 
the recipient to assert something of the form "A sent me the 
following string:"kdjglafldgfla" " , then there seems to be little 
point in the entire enterprise.

> Certainly the
>benefit (which is nonetheless present for some and in some applications) comes
>at a cost (for those who buy into inference as a given).
>I am under the impression that assertion by the document of statements
>contained within the document is a fundamental tenet of RDF and there's no
>changing it without dropping RDF. Assertion is *not* the same as truth of all
>statements or documents,

It is the claim that they are true, however. The two are closely linked.

> but it is certainly something one could question if
>one were considering RDF or not RDF.  And I might take your approach in this
>respect if I were building a language from scratch.


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Received on Friday, 1 June 2001 18:20:28 UTC

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