Why does wikipedia work?

I had an interesting conversation this morning with a colleague about community approaches to large-scale projects. We were mainly thinking about software, and in particular, the pieces of software that are most susceptible to a modular approach using a set of tools and formats that are intuitive and standard. Things like the Locale Builder and Keyboard Layout Creator, for instance -- but we were really interested in thinking about how that approach might or might not scale with projects of increasingly ambitious scope, software or otherwise. It's an interesting question.

So I started thinking about wikipedia, which I'd call a resounding success for a community-driven and -owned knowledge base. I don't know how you feel about wikipedia coverage for your own areas of expertise. However, I am routinely impressed with the coverage in the areas that I feel qualified to assess, and the quality of the content in the areas that I can evaluate makes me more likely to take the content that is newer to me at face value. I used to work with someone who spent a lot of his free time contributing to wikipedia, and at the time it never occurred to me to ask him why.

Well, now I'm asking why.

It can't be for personal visibility for the author(s), because outside the wiki community the authors aren't really known -- and if they are known, it's for their knowledge in the area among other subject matter experts, and their wikipedia work doesn't add to that. I'm pretty sure that it isn't for the money, and I'd be hard-pressed to say that it's to learn, in that the authors are typically in content-generating or -sharing mode rather than anything else.

As I list and discard possible motivations, I'm left with really only one: joy in sharing one's own knowledge, as an end in itself. I was going to say that anyone who has ever enjoyed teaching or writing a book can probably understand this, but on second thought that isn't necessarily true. A teacher or a conventionally published author gets to experience lots of other things, including every motivation listed in the paragraph above (visibility, money, learning), plus a few more (the fulfillment that comes from connecting with people and seeing them grow, to name one). The anonymous author of wikipedia articles gets none of these things.

Yet the enterprise flourishes. It's something to think about.