Modeling is difficult

21. September 2011 um 00:33 2 Kommentare

Yesterday Pete Johnston wrote a detailed blog article about difficulties of „the right“ modeling with SKOS, and FOAF in general, and about the proposed RDF property foaf:focus in particular. As Dan Brickley wrote in a recent mail „foaf:focus describes a link from a skos:Concept to ‚the thing itself‘. Not every SKOS concept (in a thesauri of classification scheme) will have such a direct „thing“, but many do, especially concepts for people and places.“

Several statements in this discussion made me laugh and smile. Don’t get me wrong – I honor Pete, Dan, and the whole Semantic Web community, but there is a regular lack of philosophy and information science. There is no such thing as ‚the thing itself‘ and all SKOS concepts are equal. Even the distinction between an RDF ‚resource‘ and an SKOS ‚concept‘ is artificial. The problem origins not from wrong modeling, which could be solved by the right RDF properties, but from different paradigms and cultures. There will always be different ways to describe the same ideas with RDF, because neither RDF nor any other technology will ever fully catch our ideas. These technologies are not about things but only about data. As William Kent wrote in Data Reality (1978): „The map is not the territory“ (by the way, last year Chris Rusbridge has quoted Kent in the context of linked data). As Erik Wilde and Robert J. Glushko wrote in a great article (2008):

RDF has succeeded beyond the wildest expectations as a convenient format for encoding information in an open and easily computable fashion. But it is just a format, and the difficult work of analysis and modeling information has not and will never go away.

Ok, they referred not to „RDF“ but to „XML“, so the quotation is wrong. But the statement is right for both data structuring methods. No matter if you put your data in XML, in RDF, or carve it in stone – there will never be a final model, because there’s more than one way to describe something.


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  1. Hi Jakob,

    Thanks for the thoughts.

    Yes, I realise Dan’s/my use of expressions like „the thing itself“/“the thing in the world“ was a bit problematic. 🙂 And I do agree our data is always the map not the territory.

    I was struggling to find generic terms to distinguish between the case where our data „talks about“:


    and the case where our data „talks about“


    And I do agree with your final point that there is always more than way to describe things, more than one „map“ – though I also think maybe some „convergence“ of our „mapping styles“ can help us when we bring our different „maps“ together.

    So really the challenge I was working through (and, I think, the motivation for the creation of properties like foaf:focus) is how/whether we can deal with those cases where there are these differences in our approaches to our maps.

    But, yes, I agree those differences aren’t going to go away.

    Comment by Pete Johnston — 21. September 2011 #

  2. At least one statement in your post made me laugh and smile. It doesn’t sound very sophisticated to me if someone criticizes others for talking about a „thing itself“ and three sentences later writes something like this:

    „There will always be different ways to describe the same ideas with RDF, because neither RDF nor any other technology will ever fully catch our ideas.“

    There you are: Our „ideas“ (whatever these are) are the things themselves! So SKOS might be your way to go to model these ideas/concepts in RDF in the end. 😉

    P.S.: And of course I btw do agree with the commonplace that modelling is a challenging task whether you do it in RDF, ERM or whatever written or diagrammatic form.

    Comment by Adrian Pohl — 27. September 2011 #

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