This last point is key — the number one fucked up thing about ontology (don’t get me started, the suckiness of ontology is going to be my ETech talk this year…), but, as I say, the number one thing, out of a rich list of such things, is the need to declare today what contains what as a prediction about the future. Let’s say I have a bunch of books on art and creativity, and no other books on creativity. Books about creativity are, for the moment, a subset of art books, which are a subset of all books.
Then I get a book about creativity in engineering. Ruh roh. I either break my ontology, or I have to separate the books on creativity, because when I did the earlier nesting, I didn’t know there would be books on creativity in engineering. A system that requires you to predict the future up front is guaranteed to get worse over time.
And the reason ontology has been even a moderately good idea for the last few hundred years is that the physical fact of books forces you to predict the future. You have to put a book somewhere when you get it, and as you get more books, you can neither reshelve constantly, nor buy enough copies of any given book to file it on all dimensions you might want to search for it on later.
Ontology is a good way to organize objects, in other words, but it is a terrible way to organize ideas, and in the period between the invention of the printing press and the invention of the symlink, we were forced to optimize for the storage and retrieval of objects, not ideas. Now, though, we can scrap of the stupid hack of modeling our worldview on the dictates of shelf space. One day the concept of creativity can be a subset of a larger category, and the next day it can become a slice that cuts across several categories. In hierarchy land, this is a crisis; in tag land, it’s an operation so simple it hardly merits comment.