People have different standards of what levels of detail are worth debating about, and on more than one occasion, I've found myself going down what I thought was a rathole with someone who insisted on arguing trivial details, only to realize that those trivial details were key elements of a chain of reasoning that led to an important point which hadn't occurred to me, and which substantively changed the direction of the conversation.
I think a tagging system is a fantastic idea, especially if users can assign different weights to different tags for sorting and filtering purposes. I haven't seen a discussion system, apart from Slashdot's very limited implementation, that allows comment tagging, and a broader implementation might be wildly successful. You could have a voting mechanic that assigns a score to the comment, then allow users to assign different coefficient values to each qualitative modifier to build their own view. No need to limit it to a small set of predefined tags, either; users could define their own tags a la Delicious.
I think a tagging system is a fantastic idea, especially if users can assign different weights to different tags for sorting and filtering purposes. I haven't seen a discussion system, apart from Slashdot's very limited implementation, that allows comment tagging, and a broader implementation might be wildly successful. You could have a voting mechanic that assigns a score to the comment, then allow users to assign different coefficient values to each qualitative modifier to build their own view. No need to limit it to a small set of predefined tags, either; users could define their own tags a la Delicious.