Not one day after my posting that tagging is really at least a little bit like categorizing, I discover this blog
in which there is a link to presentation by Thomas Vander Wal himself, in which presentation Thomas says:
People are not so much categorizing, as
providing a means to connect items
(placing hooks) and provide their meaning
in their own understanding.
providing a means to connect items
(placing hooks) and provide their meaning
in their own understanding.
I guess the first part of this disagrees with my claim that tagging does involve categorizing. Although the phrase “not so much” is a little bit confusing. Maybe they are categorizing a little bit even by Vander Wal’s reckoning?
The second part I must admit I don’t understand. What is it to “connect items” and “place hooks”? Does it literally mean to say that I can “connect” elephant with subatomic particle? What is the mechanism for this? How does it work? Does an arbitrary connection really lead to “tagging that works”?
Csaba's Blog 
this is my understanding of vanderwal’s definition: you’re connecting two objects by tagging them with the same tag, and a tag is a hook for aggregating these objects.
tagging works because of people using the same tag in the same way for the objects, this is not arbitrary but depends on “shared and emergent social structures and
behaviors, as well as related conceptual and linguistic structures
of the user community” (Marlow et al. 2006, “Position Paper, Tagging, Taxonomy, Flickr, Article,
ToRead”, p. 1)
is there only one right answer to the question “what is tagging?” i think in some (most?) cases people do categorize, others just associate or do something else… this is the reason why one cannot make assertions about the nature of tags or a tag without taking the user(s) into account.
Yes, I think I see what you mean, and I agree. If what you mean is this:
The human cognitive architecture allows us to form “shared” aggregations of various forms, not just taxonomic categories. Here is an example of two different sorts of aggregations:
1. CAT is a taxonomic category that includes several specializations like SIAMESE, BURMESE, and so on. The category structure and the applicability of the terms to various exemplars is more or less constant between people.
2. HOUSEHOLD PET is a non taxonomic category, but an aggregation of exemplars that can vary between people. A cat is probably one, but is a snake, or a crocodile? Nevertheless, there is still some deep shared understanding that allows everyone to agree that a volcano is not a household pet.
So only example 1 is the canonical case of categorization, and we should invent a different name for whatever is going on in 2.
example 2 is the sort of categorization, we do most of the time! it’s people’s everyday life categorization. it’s not a consistent categorization scheme, but most of the time it’s sufficient (e.g. for a talk with your neighbour).
Yes, again I think we agree. Except I don’t accept your claim that it is “not a consistent categorization scheme”. I actually wrote a paper about this, which you can see on http://www.springerlink.com/content/m14xuq3593268143/.
I am not sure if you can get this paper, but I give a brief overview in my post “Ad hoc categories”.
The main point is that a cognitive psychologist, Larry Barsalou, actually did try to investigate empirically the same claim, that everyday, ad hoc categories are not consistent. But in fact he found that categories like “ways to escape from the Mafia” and “things to save in a fire” were in fact remarkably stable across time and subjects, and displayed many properties of “normal” categories. (e.g. prototypicality effects). Interesting stuff.