Knowledge Organization - Evolution
The organization and categorization of knowledge has evolved from centralized taxonomies, via decentralized facets, to distributed tagging.
"Taxonomies are suitable for classifying corpora of homogeneous, stable, restricted entities with a central authority and expert or trained users, but are also expensive to build and maintain. Faceted systems (a sort of polyhierarchy) are useful with a wide range of users with different mental models and vocabularies. They are also more scalable because new items (for users) and new concepts (for cataloguers) can be added with a limited impact and with no need to start a new classification from scratch. Folksonomies require people to do the work by themselves for personal or social reasons. They are flat and ambiguous and cannot support a targeted search approach. However, they are also inexpensive, scalable and near to the language and mental model of users." (http://www.iskoi.org/doc/folksonomies.htm )
Clay Shirky has also outlined the different conditions where tagging may be better than the old models:
The old ‘ontological’ methods of cataloguing work when the domain to be organized is a small corpus with formal categories, consisting of stable and restricted entities with clear edges; the participatns are expert, authorative, coordinated. However, tagging is suited when the domain is characterized by a large corpus without formal categories, with unstanble and unrestricted entities having no clear edtes. Participants are uncoordinated amateurs without authority. (paraphrased from http://shirky.com/writings/ontology_overrated.html)
David Weinberger, on why classification can be different in digital environments:
"In the physical world, a fruit can hang from only one branch. In the digital world, objects can easily be classified in dozens or even hundreds of different categories; In the real world, multiple people use any one tree. In the digital world, there can be a different tree for each person. In the real world, the person who owns the information generally also owns and controls the tree that organizes that information. In the digital world, users can control the organization of information owned by others." (David Weinberger in Release 1.0.: http://www.release1-0.com/, reproduced in JOHO blogf)
Sorting Things Out, by communications theorists Geoffrey C. Bowker and Susan Leigh Star (The MIT Press, 2000), covers a lot of conceptual ground in this context: " After arguing that categorization is both strongly influenced by and a powerful reinforcer of ideology, it follows that revolutions (political or scientific) must change the way things are sorted in order to throw over the old system. Who knew that such simple, basic elements of thought could have such far-reaching consequences?" (Rob Lightner)