Readers have repeatedly asked me for a criterion by which we might fairly objectively decide if Iraq is in a Civil War (contrary to Bush's and Rumsfeld's denials). I have attempted such an argument at Salon.com. Excerpt:

That there should be a political controversy over whether there is a civil war in Iraq is a tribute to the Bush administration's Orwellian attention to political rhetoric. By the most widely accepted social science measure, Iraq is incontestably in a civil war.

J. David Singer and his collaborators at the University of Michigan (where I also teach) have studied dozens of such conflicts and have offered a thorough and widely adopted definition of civil war. It is:
"Sustained military combat, primarily internal, resulting in at least 1,000 battle-deaths per year, pitting central government forces against an insurgent force capable of effective resistance, determined by the latter's ability to inflict upon the government forces at least 5 percent of the fatalities that the insurgents sustain." (Errol A. Henderson and J. David Singer, "Civil War in the Post-Colonial World, 1946-92," Journal of Peace Research, Vol. 37, No. 3, May 2000.) '