W3C home > Mailing lists > Public > semantic-web@w3.org > February 2009

Re: live meaning and dead languages

From: Richard Cyganiak <richard@cyganiak.de>
Date: Tue, 10 Feb 2009 12:42:48 +0000
Cc: semantic-web@w3.org
Message-Id: <A4FE6065-DFF5-4B6B-8A57-77319518F38E@cyganiak.de>
To: rick <rick@rickmurphy.org>

Rick,

Let's continue this debate over on the armchair-semantic-web@w3.org  
list.

Cheers,
Richard

(P.S. it's a joke, I have nothing more to say on this topic)



On 10 Feb 2009, at 03:47, rick wrote:

>
> See below ...
>
> Richard Cyganiak 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 statement above makes no reference to the ROLE of the model  
> theory on the semantic web. But I'm glad you raised the issue. This  
> statement asserts the model theory on which the RDF semantics are  
> based. And the astute critic of the above would actually claim that  
> I have understated the model theory by not citing Kripke and  
> possible worlds.
>
>> The formal semantics of RDF, as defined in [1], are based on model  
>> theory.
>
> Yes, that's my assertion, too. Did you have something more specific  
> to say about which model theory? Possibly LBase?
>
>> 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.
>
> So this statement about the ROLE of model theory raises two  
> important questions:
>
> 1. If one is ignorant of model theory, does that invalidate model  
> theory?
>
> 2. If one violates the model theoretic semantics of the semantic  
> web, is the deployed usage part of the semantic web?
>
> In either case I think there answer is no.
>
> First, consider music theory as an analogy. If I play two notes B  
> and F simultaneously on my guitar that form a harmony called a  
> tritone, but I am ignorant of the music theory of tritones, are  
> these two notes any less a tritone? I believe my ignorance does  
> nothing to invalidate music theory.
>
> Second, the RDF semantics is a W3C recommendation which I understand  
> is a normative document. In addition, the LBase Working Group Note  
> defines LBase as the model theory of all semantic web languages. By  
> definition, any language whose model theory is not LBase is not a  
> semantic web language.
>
> Would you suggest the recommendation and note be deprecated to suit  
> the convenience of usage?
>
> Again, my claim is that some arm chair philosophizin' would save the  
> semantic web community some time. I'm not alone in this opinion, but  
> I suggest that's a decision made by each individual that best suits  
> their interests and abilities.
>
>> Various non-RDF technologies, such as Topic Maps or microformats  
>> are often lumped under the Semantic Web umbrella as well.
>>
>
> So is your claim that RDF technologies and non-RDF technologies that  
> violate the RDF semantics are part of the semantic web? What then  
> are the criteria for a semantic web technology? And how many other  
> technologies are semantic web technologies?
>
>> 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.
>
> As above, I suspect there's some good debate in drawing the boundary  
> around what's in this semantic web technology portfolio. Once the  
> boundary's drawn and there's agreement on questions 1 and 2 above,  
> let the philosophizin' begin.
>
>>
>>
>> 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
>>>
>>>
>>
>>
>>
>>
>
> -- 
> Rick
>
> cell: 703-201-9129
> web:  http://www.rickmurphy.org
> blog: http://phaneron.rickmurphy.org
>
>
Received on Tuesday, 10 February 2009 12:43:32 UTC

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