"Hierarchies require predictions on the future to be stable over time (fortune telling)." False and misleading. Note the derogatory "fortune telling." Taxonomies only need to reflect the past and present and include a mechanism to handle change and novelty. This is something that all good taxonomists do, but which seems not to have occurred to too many folksonomy enthusiasts.
Benefits of folksonomies
So if the majority of anti-taxonomy myths are false or overstated, what about the other side of the story, the perceived benefits of folksonomies in general and in comparison with taxonomies?
Folksonomies are easy to use.
It certainly seems on the face of it that just picking a word is a cognitively easier task than reading through a complex taxonomy and deciding which term to apply. However, there are a number of problems with that. First, picking from a simple taxonomy is at least as easy as thinking up a keyword. Second, there are ways to make it easier to select from a taxonomy, such as auto-categorization software, that automatically suggests terms from the taxonomy. In that case, the cognitive task of agreeing with the suggestion or not is much easier than trying to think up a term.
A central authority is lacking.
Being out from under the thumb of those dictatorial librarians seems to be something for which folksonomy advocates devoutly wish. I’m not sure why advocates hate the central authority of librarians so much, but there are good reasons for not taking that claim at face value. Number one is that folksonomy sites do have a central authority, and it is the most oppressive and most dangerous type of central authority there is—the authority of the majority. Against the will of the people, there is no recourse, no way of insuring the rights of the minority.
For example, the tag "design" has been in the top 25 most popular tags for the last three years. If you examine the sites that have been tagged with "design," you find that 99.9 percent of them refer to computer or software design. Pity the poor user who wants to use "design" to refer to interior design—you won’t be able to find your own bookmarks much less uncover a community of interior designers.
It seems to me that having a system in which there is a central group of authorities or librarians that you as a minority can appeal to might work better than letting the collaboratively emergent dictatorial majority unconsciously ride roughshod over the minorities.
Revolution? The limits of folksonomies
For something that is touted as revolutionary, folksonomies have major limitations that severely restrict their impact both in terms of the kinds of uses that can be made of them and the types of Web sites and environments on which they are useful.
The first limit is scale—sites like Delicious are already reaching millions of hits per tag. And a second scale limit is that, according to one study, people will only tag if they have 200 or more items to keep track of. Less than that and there was no reason to tag for personal benefit, and without a personal benefit, very few people bothered to tag much of anything. Those two scale limits severely restrict the types of sites where folksonomies can be successful.
Does all of the above anti-folksonomy rant mean that I think that folksonomies are completely useless? No, not at all. For certain limited areas and applications, they are a useful and even exciting but hardly revolutionary addition.
Within the limits discussed above, folksonomies can be a useful mechanism for their core strength—discovery of other people who have similar interests. Finding and exploring other people with common concerns, sharing the bookmarks that they have added and thereby greatly expanding your resources in those areas of interest is an exciting way to learn from and connect with people.
The real value of folksonomies or at least user-generated tags, can be realized best, however, by
First, folksonomies can be combined with taxonomies in a number of ways—from treating them as suggested terms to be added to a taxonomy, to offering user tags as additional options for browsing. Folksonomy terms as suggestions will probably be more useful, but more research must be done both on enterprise intranets and public sites like Factiva, which includes user-generated tags with taxonomies and facets.