Re: live meaning and dead languages

Hi Richard --

You wrote...

*...that's overstating the role of model theory on the Semantic Web. The
formal semantics of RDF, as defined in [1], are based on model theory. But a
lot of the deployed usage of RDF considers it simply as a distributed graph
data model, and ignores (or even violates) the model theoretic semantics.*

The trouble is, if you don't have some kind of reference for what is
supposed to be deducible, then the results you get are implementation
dependent.

In the non-SW area, the SQL language suffers from this.  There is a SQL
query that gives different results in Oracle and in MySQL.  Neither of the
results is intuitively correct to most people.

In [1], it's argued that this problem is much more serious for the SW.

                                     Cheers,  - Adrian

[1]  www.w3.org/2004/12/rules-ws/paper/19

Internet Business Logic
A Wiki and SOA Endpoint for Executable Open Vocabulary English over SQL and
RDF
Online at www.reengineeringllc.com    Shared use is free

Adrian Walker
Reengineering


On Sun, Feb 8, 2009 at 5:57 PM, Richard Cyganiak <richard@cyganiak.de>wrote:

>
> On 8 Feb 2009, at 18:11, rick wrote:
>
>> As I have written before, the model theory on which the semantic web is
>> based is defined in Alfred Tarski's Semantic Conception of Truth.
>>
>
> Rick, that's overstating the role of model theory on the Semantic Web. The
> formal semantics of RDF, as defined in [1], are based on model theory. But a
> lot of the deployed usage of RDF considers it simply as a distributed graph
> data model, and ignores (or even violates) the model theoretic semantics.
> Various non-RDF technologies, such as Topic Maps or microformats are often
> lumped under the Semantic Web umbrella as well.
>
> So, only a particular part of the Semantic Web technology portfolio is
> based on model theory. I agree, however, that it's the part that can benefit
> most from armchair philosophizing.
>
> Have fun,
> Richard
>
> [1] http://www.w3.org/TR/rdf-mt/
>
>
>
>  Briefly, Tarski defines truth in terms of material adequacy and formal
>> correctness. Note that Tarski does not define meaning, only truth. I think
>> everyone would agree that material adequacy applies only to resources can be
>> dereferenced and that  it is formal correctness that provides the foundation
>> for inference.
>>
>> So what can we say about meaning on the semantic web? We can say that URIs
>> are definitions, but we need to be clear that meaning is not definition.
>> Quine writes about this in Two Dogmas of Empiricism. Live meaning as
>> referenced above implies interpretation.
>>
>> The question then is whether inference is interpretation. I believe
>> inference as used on the semantic web is necessary, but not sufficient for
>> interpretation. Interpretation as it applies to meaning implies abduction as
>> well as induction and deduction. Inference on the semantic web implies
>> formal correctness and truth.
>>
>> It's not clear whether the semantic web lacks this design principle
>> intentionally, but without this design principle, the semantic web will lag
>> the web in its utility.
>>
>> As a compelling example, consider how the web serves as a meme pool for
>> cultural transmission. How would we expect the semantic web to serve as a
>> meme pool with dead languages ?
>>
>>  I think this worry becomes more so as axioms and systems of axioms become
>>> more complicated. (I just about see similarities between OWL2 and the
>>> Shorter Latin Primer I had at high school).
>>>
>>> A term which is too tightly nailed down in its relationship to other
>>> terms has been dug into an early grave. Having fixed its meaning, as our
>>> world moves on, the term will become useless.
>>>
>>>  A semiotic domain is a good next step to start developing this
>> flexibility.
>>
>>> The trick, in natural language, is that the meaning of terms is somewhat
>>> loose, and moves with the times, while still having some limits.
>>> This looseness of definition gives rise to some misunderstandings (aka
>>> interoperability failures), but not too many, we hope.
>>>
>>>
>>>  Pragmatics is a step after semiotics.
>>
>>> So I wonder, as some people try to describe some part of their world with
>>> great precision, using the latest and greatest formal techniques, just how
>>> long that way of describing the world will last. Maybe there is a role in
>>> such precision in allowing us to be clear about differences of opinion ---
>>> but it doesn't seem to me to be a good foundation for building knowledge.
>>>
>>>
>>>  While I agree that we need to recognize the limitations of where we are
>> today, I think Tarski's Semantic Conception of Truth is a pretty good place
>> to start. We also need to recognize the challenges of moving along the path
>> to live meaning.
>>
>> If you're looking for some fun reading, Robert Kent has already defined
>> the Information Flow Framework which parameterizes languages, logics, models
>> and theories into a much more flexible approach than the semantic web. But
>> hold onto your towel ...
>>
>> http://www.ontologos.org/IFF/IFF.html
>>
>>> Perhaps fortunately, I am an engineer not a philosopher!
>>>
>>> Jeremy
>>>
>>>
>>> [1] Don Cupitt, 2001, Emptiness and Brightness,  p95
>>>
>>>
>>>
>>>
>>>
>>>
>> --
>> Rick
>>
>> cell: 703-201-9129
>> web:  http://www.rickmurphy.org
>> blog: http://phaneron.rickmurphy.org
>>
>>
>>
>
>