Graham's Hierarchy of Disagreement

Partially related to my last post, here are a couple of things worth looking at in regards to discussion and disagreement:

An article relevant to the above pyramid can be found at http://www.paulgraham.com/disagree.html

Note: the above image is not mine, and has been taken from http://en.wikipedia.org/wiki/File:Graham%27s_Hierarchy_of_Disagreement.jpg. Licensing is documented on that page.