He's too good at math.

Hindsight has a way of making history seem inevitable. Two years ago, when Paul Wolfowitz was named World Bank president, I wrote that he was "not so bad a choice" for the job. Now it seems he was a terrible pick, and for reasons that should have been plain.

My (unenthusiastic) endorsement stemmed from an impression that, of all the neocons, Wolfowitz seemed to be the most genuinely idealistic—that, despite his disastrous misjudgments on Iraq, he was the sort of "optimistic globalist" who believed in the bank's basic tenet: that the developed world can improve the underdeveloped world with the aid of rational principles.

What's clear in retrospect is that judgment and character trump dedication and belief—and, in this regard, Wolfowitz's doom was all but fated.

Several factors shaped this fate, but not least was the fact that his major in college was math. I've known a few mathematicians who have gone into policy analysis, and they share not merely an intolerance of bureaucracy but a disdain toward all political processes. In math, methodologies and answers are right or wrong, and those who choose the wrong ones are properly ignored or savagely dismissed. Mathematicians who enter the political realm tend to retain this attitude.

Some mathematicians at least bring an analytical rigor to calculations of policy, and perhaps Wolfowitz did, too, in his early years under Jimmy Carter and the first George Bush. But his career's pivotal chapters were shaped by ideological disputes—the anti-détente rebellion within the Republican Party, the "Team B" hawks' hyping of the Soviet threat, and, later, in his exile during Bill Clinton's presidency, the planning and petitioning for a more aggressive unilateral foreign policy, especially for "regime change" in Iraq. The legacy of those battles, it seemed, came to dominate his whole style of thinking and behaving.

In his period of exile, Wolfowitz's stature rose—to that of "intellectual godfather"—within a clique of exiles who met regularly for seminars and luncheons at such neocon think tanks as the American Enterprise Institute and the newly created Project for a New American Century. And when the Republicans won back the White House, many members of this clique moved, along with Wolfowitz, into key positions of influence.

Here, then, we had a mathematician, predisposed to viewing ideas (and those who hold them) as starkly right or wrong. This tendency was reinforced by a coterie of like-minded mentors and acolytes. (It may be pertinent that two of his most important mentors, military strategist Albert Wohlstetter and Iraqi exile Ahmad Chalabi, were also mathematicians by training.) The resulting righteousness was abated by neither political shrewdness nor managerial acumen. (Wolfowitz was a famously indifferent administrator as deputy secretary of defense, an appointment that also puzzled many, as the job of most deputy secretaries had been precisely to manage the Pentagon.)

His main flaw in the Pentagon was not that he was wrong about Iraq—everybody is wrong about something, and many were wrong about that country—but rather that his inflexible, largely theoretical style of thinking impeded him from detecting when he was wrong or how to make things right.

The signature moment may have been his dismissive riposte to the pre-war prediction by Gen. Eric Shinseki, then the Army chief of staff, that a few hundred thousand U.S. troops would be needed to impose order after the fighting. "It's hard to conceive," Wolfowitz testified before the Senate armed services committee, "that it would take more forces to provide stability in post-Saddam Iraq than it would take to conduct the war itself and secure the surrender of Saddam's security forces and his army. Hard to believe." (Emphasis added.)

Had Wolfowitz consulted anyone who'd studied the actual history of occupations (and one such historian was a former colleague of his), he would have learned that, in these sorts of conflicts, more forces are almost always needed for post-war stabilization than for securing victory on the battlefield. Wolfowitz's chief failure, in other words, was a failure of imagination—or at least a failure to step outside his preconceptions (and outside his clique, which shared them) to see if they aligned with reality.