History professors should give the Sept. 11 commission's final report a solid A as an illuminating chronology pulled together on the gallop. History itself is not likely to be as kind. The report has conceptual holes and works too hard to round off the necessary rough edges of politics and national strategy.

The commission investigating the 2001 terrorist assault on New York and the Pentagon follows the Senate Select Committee on Intelligence in pinpointing causes for the woeful performance of the CIA and other government agencies in fighting al Qaeda and other enemies. It also suggests organizational fixes for what it christens the war on "Islamist terrorism."

But both these inquiries step gingerly around a central question that John Kerry is also likely to handle delicately when he addresses antiwar Democrats assembled in Boston tonight. It is the role -- if any -- that preemptive strikes or preventive war should play in protecting the United States from terrorist groups that possess or seek chemical, biological or radiological weapons.

Indulging a blue-ribbon panel's instinctual penchant for the obvious, the commission mandates future administrations to "attack terrorists and their organizations" and permit them no sanctuaries. It adds: "[T]he U.S. government must build the capacities to prevent a 9/11-scale plot from succeeding."

Those conclusions make sense in a report that dwells heavily and persuasively on the failures of the Clinton and Bush administrations to take effective (i.e., preemptive) action to thwart the Sept. 11 plot as it was being refined in the caves of Afghanistan.

But the commissioners are then mostly silent on getting there from here; that is, on specific measures to accomplish those particular goals. They are totally silent on preventive war, a concept that is enshrined in the Bush administration's National Security Strategy.

Commission member Jamie Gorelick told Post editors and reporters that the doctrine and practices of preemption were deliberately kept out of the commission's closed-door discussions in a successful bid to avoid partisan arguments.

The description of private harmony from Democrat Gorelick and Republican Slade Gorton stood in contrast to the knife-between-clenched-teeth approach of many commission members during the public sessions I watched. Might it have been better if the commissioners had argued out the big questions of the principles and tactics of national security in private and sought common ground there? I happen to think so.

But the larger point that is ducked by the Senate and commission reports comes from an unwillingness to look directly at the consequences that flow from their two most important findings.

Both reports find that the United States faces a severe threat from global terrorist networks -- and does not have an intelligence organization capable of providing the clear-cut, unequivocal intelligence on the threat that any leader would want in making a mass life-or-death decision.

The reports are nonetheless useful debunking tools. They puncture the exaggerated claims that the intelligence failures on Sept. 11 and Iraq were a result of political manipulation and pressure by either the Clinton or Bush White Houses, or by Iraqi exiles. The true culprits were "group think" and other forms of faulty reporting and analysis by the agencies themselves on Iraq, and our government's appalling inability to internally share and track information on al Qaeda before Sept. 11.

But having diagrammed the past with lucidity and skill, the Sept. 11 commission cast surprisingly little useful light on the future. Its call for a national intelligence director to overhaul the mess -- enthusiastically backed by Kerry and gaining favor with the White House -- could actually make things worse.

Having one policymaker oversee both intelligence operations and analysis at the Cabinet level would mingle and corrupt both functions even more thoroughly than did the ascension of then-CIA Director George Tenet to President Bush's buddy, analyst in chief and an important if hidden voice on policy. The dangers to civil liberties from an intelligence czar have been pointed out more clearly in recent days by contrarian conservative columnist William Safire than by Democratic liberals in Boston.

Bush's continuing defense of preemption -- see his July 12 speech on Iraq -- and the Democrats' equivocation in their platform, which condemns "unilateral" preemption but not any other kind, both skirt a more complex reality that an experienced national political leader expressed to me recently:

"Most of the time you are not going to have perfect knowledge for making decisions. If you look at the way Saddam Hussein acted, any reasonable person would have concluded that he was hiding those weapons, just from what he said and did. The key point is always going to be the judgment you then make from what is almost always imperfect intelligence."