I was able to watch Sam pitch his first class yesterday on his theory. 1. Sam is amazingly intelligent. He is a speaker, writer, and reader of Arabic. 2. His presentation is very animated – he’s excited about this topic. 3. He is very well read on his sources having personally translated many of them.

Yeah – he had a shameless plug for his book and I’ll buy a copy if just to read what he translated since my Arabic reading isn’t so good. If you can get over the plug (and you really should), as davidbfpo above pointed out, he brings a level of specialism that is not found elsewhere that I know of.
His basic point – and Sam if I got this wrong, then tell me – is that there are tribes in Iraq (the Noble Tribes) that drive the society (drive may not be the right word, so I’ll go “Where the Noble Tribes go, so goes the country.)

As far as what Tom Odom says above, the “necessary” of what Sam does can be explained in the question, “What motivates Iraqi X to do what he is doing?” I served as a MiTT Chief for a year in addition to commanding a rifle company in Baghdad. The full tribe name of the Iraqis that I worked with can explain some of what they did (in retrospect since I was not aware of the importance of sub-tribe/clan until yesterday). It’s deeper than just “Mr Maliki” or Saddam Hussein al-Tikriti – what about the albu Nasirs that Saddam belongs to? How do you talk to them? How about the fact that there are Malikis all over the country and their power base is much larger than that of any other tribe cross province (there are more of certain tribes in certain provinces, but cross province – the Malikis take it.

Scott