A blog post by Alistair Roberts, as curated by Steve Sailer. (Steve's version is shorter and more targeted; the original blog post is the fourth in a series on triggering and suffers for its reliance on the particular issue.)
It seems like a very useful dichotomy, and strongly reminds me of Ask and Guess.
One point which stuck out to me:
So when discourse_1 argues with discourse_2, discourse_1 takes offense and closes down the discussion, leaving both sides interpreting themselves as the victor in the discussion.
One obvious problem I see for discourse_1 discussions - when you can score points by taking offense, there is a natural death spiral of taking more and more and more offense.
Managed to find an old Bloom County cartoon: Offensitivity http://www.explorerforum.com/photopost/data/503/medium/4156bloom.jpg
Yes. Either that, or it empowers martinets to come up with petty etiquette norms and declare that someone's approach is "rude" or "trollish", regardless of their actual merits. This is especially ironic when the debate itself involves important issues in ethics, empathy or similar: the person with the most ethical or empathetic position in the debate can nonetheless end up being silenced.