The blogosphere still feels largely like a boundless op-ed page. And opinion columns often serve mainly to validate the views and passions of like-minded people. But there's a growing effort to figure out how to attack and solve problems with this fascinating interactive communication tool... Dr. Klein's group is designing an "argument tree" in which contributions must fit into one of four categories: issues needing addressing, options for resolving them, information supporting an option and information rebutting one.