A discussion at work today had me thinking about the differences between blog comments and forum posts. It originated out of this assertion by Martin Dougiamas, the lead developer at Moodle, saying that he wouldn't give the blog module comments because there is no difference between a blog comment and a forum posting.
Unfortunately, Martin is wrong. His assertion that forums replace commenting in blogs is fundamentally flawed, and in my opinion betrays a lack of understanding of how blogs function. One of the key affordances that blog commenting offers is a discussion in context of the original material. Removing the comments to a separate area breaks that contextual link.
At a very broad level, yes, forums offer a similar set of functionality; but if that's really the case, then why have blogs at all - why not just post to the forum? The reason is that the blog offers a different kind of interaction than the forum, and has a different set of behaviours for authors and contributors (the blogger vs. the original poster) in the initial act of authoring. Jeremy Finke gives a good summary: "Blogging is a one to many communication. Forums are a many to many communication." Another way of putting it is that blogs offer the creation of a specialized community, whereas forums offer the creation of a generalized community.
My contention with Martin's assertion, however, is in the removal of context. Comments on blogs work well because there's a very tight correlation with the original material and the comments that follow, and all of the activity is contained within a single location. Using Forums for blog comments, as I mentioned, breaks that contextual link, and creates a separation between the original content and the discussion it inspires. Forum posters have to go outside of the discussion to read the original material (if there's even a link back to it, which in the Moodle Blog module there is not) in order to make a meaningful contribution (remember, if you're posting the original material to the forum, there's no actual need for the blog in the first place), and the potential for derailing the discussion is much higher.
As well, in Martin's/Moodle's model, the blogger and his/her readers now have to go searching through the Forums to see if the original blog entry has inspired discussion; in the blog comment module, it is immediately apparent whether or not a discussion has emerged from the post just by reading it.
Another key function that blog comments offer is for the blogger to moderate the discussion, and give them ownership over it. As soon as you remove the comments to a forum, the blogger loses any control over the ensuing discussion.
So what do you think - can a forum serve as an effective communication tool for blogging?
Here are the slides from the talk I gave in Finland..