Ernest Becker, the Pulitzer Prize winning author, wrote, “In order to turn out a piece of work the author has to exaggerate the emphasis of it, to oppose it in a forcefully competitive way to other versions of the truth…the problem is to find the truth underneath the exaggeration.”
"More than thirteen years after the U.S. intelligence community named the prevention of terrorism its number one goal, it seems to have little understanding of what drives terrorism, or how to counter it. And, if the recently increasing criticism is correct, the government’s investment in academic terrorism research isn’t helping. It may be because the government is continuing to fund research supporting discredited theories of terrorist radicalization, rather than objective empirical analyses."
The difficulty and challenge is being able to have a solid metrics system and equation in reaching solid conclusions. Whether you agree with Michael's assessment that seems to point to American intervention as a more serious problem than extreme religious ideology it is difficult to sift through human motives and which one is more dominant than the other.
To be sure Americanism is part of the drama. So is the history of Ba'athism and Islamism. How does one go about deconstructing which variable is more important than the other? How do you create a reliable equation that includes all the factors? The Iran and Iraq war of the 1980's versus the invasion of Kuwait by Saddam or the invasion by America? How do you determine and divide the quantity of the pie factor causation?
The pie consists of many moving pieces from geopolitics, ideology, psychology, historical and cultural movements, war...et cetera.
I think Zack Beauchamp does a good as job as any in trying to encompass all the factors and variables in the rise of ISIS. See his article here.
Also combining "objective empirical analysis" assumes those analyzing and those being analyzed are rational actors which is rarely the case. Human beings are motivated by many factors including factors that are hard to quantify and pin it down to some metric system. I agree with the drive to be more empirical and stay close to factual causation however there needs to be checks and balances to even those groups who claim objectivity because each think tank or person may have their own agenda including Michael German.