AP Photo

MacDILL AIR FORCE BASE, Fla. -- When asked whether nationalism is putting down roots in Afghanistan's tribalized society, Gen. David Petraeus is judicious: "I don't know that I could say that." He adds, however, that "we do polling" on that subject. When his questioner expresses skepticism about the feasibility of psephology -- measuring opinion -- concerning an abstraction such as nationalism in a chaotic, secretive and suspicious semi-nation, Petraeus, his pride aroused, protests: "I took research methodology" at Princeton. There he acquired a Ph.D. in just two years: His voracious appetite for knowing things is the leitmotif of his career.

Petraeus thinks he knows that President Hamid Karzai is widely viewed as "the father of the new Afghanistan." Although there was...