It's controversial, and arguments about it have spilled out on such sites as Kings of War, Line of Departure and Small Wars Journal, so it's worth commenting on when the august journal International Security leads with "Testing the Surge: Why Did Violence Decline in Iraq in 2007?"
The narrative is by now familiar. From 2004 to mid 2007 Iraq was violent, then it became relatively calm. Relative calm is just that, relative. The authors do well to note that Iraq today "is no Garden of Eden". Operational execution of suicide bombing has increased in proficiency to the extent that detonations now invariably cause deaths between 50-100 people in the country. Police stations are still highly desirable targets.
So what of the surge? It draws argument because of the concatenation of circumstances and the various narratives at play. It was the start of population-centric coin en masse; FM 3-24 had been published in December 2006. So COIN doctrine was necessarily foregrounded in US policy circles as having reduced violence from 2007 onwards.
David H. Ucko wrote an article in PRISM, the NDU's journal in which he considered factors at play in the reduction of violence in Iraq in 2007, but this new article by Biddle et alia is by far the most comprehensive examination of the matter using declassified Significant Activity charts (SIGACTs) to provide a quantitative aspect to the analysis.
The conclusion? Quite mainstream. The surge itself is an insufficient explanation as to the violence reduction witnessed, rather it remains the most likely answer that it was a dynamic between the Awakening of tribal units coupled with the increase in manpower afforded the US military on the ground. Indeed, as regards academic debate on the influence of the surge, Biddle et alia decide that "Our analysis, however, suggests a mixed verdict." Which points to the problem of human variables and the insufficiency of current quantitative analysis to examine such variables. We can only try and Biddle at alia's article is the best attempt yet to assess the surge.