Clay Shirky here. I’ve been writing about tagging since late 2003, when I first wrote about del.icio.us over on Many-to-Many (a group weblog about social software.) By way of introduction, here are excerpts from some of my M2M posts on the subject of tagging and folksonomy:

Folksonomies + controlled vocabularies: “The advantage of folksonomies isn’t that they’re better than controlled vocabularies, it’s that they’re better than nothing, because controlled vocabularies are not extensible to the majority of cases where tagging is needed.”

Folksonomies are a forced move: “It doesn’t matter whether we “accept” folksonomies, because we’re not going to be given that choice. The mass amateurization of publishing means the mass amateurization of cataloging is a forced move.”

The Innovator’s Lemma: “If we’re going to let just any old person write whatever they want and then make it available globally, we’re going to have to extend the same freedom to classifying the resulting flood of material. And critics will be able to say, rightly, that such a system will lack the coherence we would have had, had we not gone and let everyone publish willy-nilly. To which the only sensible reply is “Oh well.”

Tags != folksonomies && Tags != Flat name spaces: “This last point is key — the number one fucked up thing about ontology, out of a rich list of such things, is the need to declare today what category contains what as a prediction about the future. … A system that requires you to predict the future up front is guaranteed to get worse over time.”

Folksonomy: The Soylent Green of the 21st Century: “Every time you pick between the Heinz and the Del Monte, it’s like clicking a link, the simplest possible informative transaction. Your choice says “The Heinz, at $2.25 per 28 oz., is a better buy than the Del Monte at $1.89.” This is so simple it doesn’t seem like you’re producing metadata at all — you’re just getting ketchup for your fish sticks. … That looks like cheap metadata to me. And the secret is that that metadata is created through aggregate interaction.”