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Re: a simple question

From: Bijan Parsia <bparsia@isr.umd.edu>
Date: Fri, 19 Dec 2003 23:31:16 -0500
Message-Id: <59CD41B4-32A5-11D8-B7A0-0003936A0B26@isr.umd.edu>
Cc: pat hayes <phayes@ihmc.us>, www-rdf-rules@w3.org
To: Drew McDermott <drew.mcdermott@yale.edu>

On Dec 19, 2003, at 9:08 PM, Drew McDermott wrote:

>    [Pat Hayes]
>    I think we are talking at cross purposes and in fact agree on almost
>    everything except rhetoric.
> Probably.  I certainly agree on much of what you say in your posting.
> However, ....

Including, grumble grumble, quoting style. Leading whitespace often 
gets mangled!

>    ----------
> What follows are several quotes from Pat's posting to the effect that
> we can and should distinguish "techniques" from "justifications":
>    This confuses two issues: strategies for useful reasoning are one
>    thing, justifications of conclusions are another.
>    ...
>    There is a deep-seated fallacy surfacing here, to the effect that 
> the
>    use of logic (or indeed anything else, but it seems to be usually
>    invoked by the use of the L-word) as a representational language
>    *requires* that a certain kind of mechanism be used to process it. 
> If

Hmm. Is that really what's surfacing? I mean, there's a fairly natural 
bias toward, if possible and practical, using sound & complete decision 
procedures. Or, at least, sound & complete reasoning mechanisms. But I 
think the If Possible and Practical codicil is firmly in place.

Sure, lots of semweb reasoning will be done by random Perl and Python 
scripts (or fairly cheap prolog hacks). But there's some sort of 
difference between acknowledging that and wanting to privilege "certain 
kinds of processing mechanisms" for interoperability purposes. And 
interop is somewhat the name of the game, I'm pretty sure.

>    ...
>    No,  it has got nothing to do with showing anything about 
> techniques.
>    People should, and will, use whatever techniques they find useful,
>    and good luck to them.  None of the SW specs (RDF, RDFS, OWL) say
>    anything about what  techniques can or must be used to process these
>    languages (except for owl:imports).

Surely they do, at least by their silence. If you are going to use 
those specs as the basis of judgments about interoperability or 
correctness of inferences, then it's pretty clear that a variety of 
classes of inference procedures are going to be incorrect. And since 
they can be incorrect in different ways, they will have 
interoperability issues.

>    We need both, but
>    we need to keep their roles clearly distinguished. To point out that
>    NAF is not a good foundation for truth-justification in general is
>    not to say that all SW reasoning must be done by clunky
>    general-purpose inference engines.
> It's this distinction between techniques and justifications that I
> want to deny.  I wish it were not so.

It seems to me that if you two are disagreeing on this, then you are 
disagreeing on quite a bit ;) Including a bit which has some 
consequences for the task at hand, specifying and standardizing 
representation languages.

[snip nice paragraph that seems straight out of Critque of Pure Reason]

So, Drew, is there any evolution in your position in CoPR and that 
paragraph? In your experience?

> In the following fragment, I believe you overstated your case:
>    In fact a reasoner is not even obligated to use a valid or 
> guaranteed
>    correct inference method. It might for example cut corners by 
> assuming
>    names are unique. its conclusions will not be valid, in general, but
>    nothing in the semantic specification of the language requires that
>    all reasoners only perform valid inferences.
> If you really stand by this, then there really is no difference in our
> positions.  The assumption set, in this case, will include an
> assumption that "the algorithm did not err on this occasion."  How
> would one check that without reopening the original question?

Er...isn't the difference that you think the assumption isn't checkable 
(in fact) whereas Pat thinks that it is?

Bijan Parsia.
Received on Friday, 19 December 2003 23:33:45 UTC

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