How to Disagree

An interesting essay by Paul Graham reviews how the web has transformed our communication and takes a detailed look at how people disagree in comment threads,  forums, and blogs.  Creating a disagreement hierarchy, Paul describes the following 7 stages:

DH0. Name-calling
DH1. Ad Hominem
DH2. Responding to Tone
DH3. Contradiction
DH4. Counterargument
DH5. Refutation
DH6. Refuting the Central Point

What is the advantage of classifying these types of disagreements?  According to Paul, this will help people better understand what they read - allowing them to weed out intellectually dishonest arguments.