W3C home > Mailing lists > Public > www-rdf-logic@w3.org > April 2002

Re: Some DAML clarification

From: Steven Gollery <sgollery@cadrc.calpoly.edu>
Date: Sun, 07 Apr 2002 15:33:59 -0700
Message-ID: <3CB0C957.2EB7C79B@cadrc.calpoly.edu>
To: www-rdf-logic@w3.org

I'd like to try to put this in terms that don't involve eccentric 19th
century British mathematicians and characters from Greek mythology: Let me
know if I've got it right, okay?

At some point any system of logic and semantics must rely on the existence
of something outside itself. In Charlie's case, the connection between
Premise (as a concept) and Conclusion (also as a concept) exists, not in
the ontology, but in the inferencing engine -- in fact, it's part of the
definition of what an inference engine is. Rules about rules eventually
come to an end, and then the inferencing engine has to rely on some
"innate" built-in behavior to process them.

The same thing is true of any attempt to define "meaning" in an ontology:
it only works if we assume that whatever is processing the ontology
(whether the processor is human or software) already possesses an
underlying context for that meaning. Ontologies (and ontology definition
languages) cannot be self-contained.

Steven Gollery

Drew McDermott wrote:

>    [Charlie Abela]
>       A question that has been haunting me these days is how, if
>    possible, to match within an ontology, the premise and its
>    conclusion. Inferencing must play a role here, but still there has
>    to be some declared form of connection between the two.
>    [me]
>    I don't understand this part
>    of your e-mail.  Can you
>    elaborate?
>    [Charlie]
>    I mean the following;
>    Every rule will have a means of declaring its premises and
>    conclusion, as in the example listed earlier.  Now assuming that
>    some form of reasoner is going to be used.  And given a premise (
>    such as one containing a triple) the reasoner must match with a
>    premise/ or premises in a particular rule and infer its
>    conclusion. How will this inference come about?  I am not sure how
>    this process should be handled. Should there be some property in a
>    basic rules ontology that connects a premise to a particular
>    conclusion ? Sort of
>    If
>      Premise A
>    Then
>     Conclusion B
>    And in the basic ontology there would be defined in some way that:
>    Premise leadsTo Conclusion So inference engine upon given Premise A
>    will try to find a rule that matches this Premise and the infer its
>    Conclusion
>    Hope I am not making a mess out of this and have explained more the
>    issue
> It sounds like you have fallen prey to the "Achilles and Tortoise"
> fallacy described by Lewis Carroll.  Perhaps someone can post a
> pointer to an online copy of it, you can read it, and Enlightenment
> will settle over you.
> The fallacy is to suppose that because a rule says "From P conclude
> Q," there must be another rule somewhere that says "If a rule says
> 'From P conclude Q', and you have concluded P, then you must conclude
> Q."  An infinite regress suddenly yawns before us.
> The most remarkable example of the fallacy I ever came across was in
> an otherwise good book about programmed cell death and other
> biological wonders, where the author made the suggestion that
> somewhere deep inside DNA there is a message saying "Reproduce!"
>                                              -- Drew McDermott
Received on Sunday, 7 April 2002 18:33:14 UTC

This archive was generated by hypermail 2.3.1 : Wednesday, 2 March 2016 11:10:37 UTC