Dan Bricklin picks up a thread from Shelley to AKMA and Winer on blog post categorization (David Weinberger tracks it, but also see his recent newsletter on tags and Jay's comments) to suggest Guiltlessness as a design criteria for a type of successful system.

In Cornucopia of Cooperation and Social Spillover, I suggested that tagging was an example of the Volunteer Manual method of building a database. I still find this true, because:

• Blog post categorization is still not tagging, but will be soon
• Tagging in del.icio.us and Flickr supports freeloading and rewards contribution

Categorization in blogging still lacks a easy tagging interface. In Typepad today, for example, you have to (a) add a new tag to your list, and (b) be done if you want just one tag, or (b) select multiple tags from your list. Encouraging one tag is categorization, is the pursuit of topic by design.

The Topic Exchange (nod to Phillip and M2M's Seb) lets you categorize your post through a trackback or manual entry into a topic channel on an aggregating site. More persistent groups within this system had a fascination with RidiculouslyEasyGroupForming, such as social software bloggers. Easy New Topics (nod to Matt and Paolo), took additional steps to enable extensible categorization within the blog client and easy group forming around topics. K-collector's pioneering implementation of ENT did bring together some early adopter bloggers around select topics, not too coincidentally among those more fascinated with ontology like KM bloggers. Note that contribution to these systems is not a byproduct of regular use (without adding a category, your post is not added to the database) and has relatively high transaction costs. Since use centers around formed groups, I would agree that guilt may come into play.

You can, and many do, use del.icio.us and Flickr without adding tags to links and pictures as objects. You still contribute value to the system, the object itself, which others can pick out of the stream to add value. When you do tag, however, you gain the reward of your own organization and the emergent structure of the group. Use centers, first and foremost, around individuals instead of groups, so guilt is barely a factor.

Dan's original example of Napster demonstrated Cornucopia effects where Greed is Good. You can take advantage of the common resource, but as a byproduct, you contribute to the commons, thereby increasing its value. But it must be noted that in some social systems, Guilt is Good. In particular, it can be used to curb negative behavior and even freeloading, which can increase the value of the system. UCLA researchers have highlighted the role of shunning in social systems:

Perhaps a system isn't social if it only has first order commons dilemmas (governing the resource) and doesn't support management of the second order (governing each other). When a group explicitly forms around a tag, guilt may come into play (for example, shame on you people for not posting really ugly and fairly pointless parking lot photos!), and that's not necessarily a bad thing.