Online as well as in the real world, a discussion is only productive if participation is curated. A discussion can be represented as a tree — okay, an upside-down tree — in which the trunk represents the column of replies in which the author has participated and the branches maybe the line along which the author's contacts veer off.
But to adapt a criticism often applied to sloppy thought or argument: we can't see the wood for the tree, because of all the twigs and leaves that get in the way. The momentum of a conversation is killed by spam and smarm, the threads become unintelligible, as much as the shape of a tree is obscured by over-exuberant foliage.
To reveal the underlying discussion, Kinja filters comments in three ways:
1. Thinning. Kinja establishes a circle stretching two or more degrees from the original author, including those readers with whom the author has interacted on this topic, people they've responded or even contacts that they follow or popular Kinja users beyond that. Some popular discussions attract hundreds or thousands of participants. Limiting that to 10 people — a minyan of commenters — thins the tree to the point that its structure becomes visible.
2. Pruning. The starter post and the main trunk of discussion will always be displayed, no matter how long ago they were published. They provide an introduction essential to the understanding of the live conversation. But we will prioritize the display of more recent responses; and collapse those that have not elicited replies. That further reduces the complexity of tree.
3. Pivoting. In order fully to visualize a tree or any other structure, you need to examine it from different points of view. The author's perspective is not the only one. If a reader doesn't relate to the circle chosen by the author, they can pivot to another. And if the author is absent, others can move the discussion forward.