Like many Americans, I decided in early 2003 that a war with Iraq was increasingly necessary. War seemed justifiable because of the intelligence reports concerning Iraq’s weapons programs and because Saddam Hussein, who had committed atrocities in the past, was likely to be highly dangerous if he acquired weapons of mass destruction. The arguments for war could be supported by reference to the well-known just war theory.

I now believe that the war was deeply misguided. For just war theory—a framework of ethical reasoning with a long history in Christian thought—to remain plausible, its advocates need to acknowledge the weak arguments that they have embraced. Only by coming clean on our errors can we think more clearly in the future.

The first criterion of just war, and the one on which I’ll focus, is that there be a “just cause.” There were two potentially persuasive arguments for just cause in regard to Iraq. First was the claim that it was developing weapons of mass destruction in contravention of United Nations Security Council resolutions and was stymieing the work of UN weapons inspectors. The intelligence agencies of several nations presented reasons to believe that Iraq had retained materials for such weapons after the Gulf War of 1991 and that it had weapons programs under way. Even after Iraq readmitted UN weapons inspectors in November 2002, the regime was making it very difficult for them to do their work. These developments persuaded many people that Iraq posed an imminent threat, and that the threat constituted a just cause for war.

A humanitarian version of the argument for just cause was crucial for liberal hawks and tugged at the consciences of many Christians. Saddam Hussein was broadly acknowledged to be a dictator who wasted the resources of his country, murdered political enemies and brutally repressed his citizens. His repression included using chemical weapons against Kurds. Although in 2003 no acts of genocide were occurring or looming in Iraq, those who pushed the humanitarian just cause argument took a long view: large-scale atrocities had happened, and they deserved a just response; Iraqi citizens faced ongoing oppression and killing; future oppression and atrocities were all but certain to occur.

The just cause of addressing weapons of mass destruction collapsed after investigations by the press and by governmental and independent commissions revealed deep flaws in the intelligence. This much has become clear about the Bush administration: it put pressure on the intelligence community to paper over ambiguities in the evidence on Iraq’s weapons and to make assessments that would bolster the case for war, and it exaggerated to the public the clarity of the intelligence. Those who have repented of their initial support for the war can place a portion of the blame on the politicians and intelligence experts who had the actual evidence and assessments.

Another problem with the argument for just cause was that it was applied to a preventive war. The just war tradition has long allowed preemptive attacks in the face of an immediate threat, viewing such attacks as in the category of self-defense. But the just cause argument has never been used to defend a preventive war—a war to preclude a future threat from emerging. One’s judgment as to whether the invasion of Iraq qualified as preemption or prevention depends both on keeping the conceptual distinction straight and getting the facts right. I myself did not consider the war to be preventive at first, but I was one of many who blurred the distinction by maintaining that it was Saddam’s noncooperation that was the issue rather than an objective assessment of the risk based on evidence. It should have been clear enough, with inspectors in Iraq, that Saddam was in no position to launch any kind of attack imminently.

A second criterion of just war is the principle of proportionality—the attacking nation has to consider the long-term ramifications. A war wouldn’t be just if the civilians of Iraq were likely to be worse off afterward. If a better outcome was dubious from the beginning, the war should probably not have been fought.

Are Iraqis better off or worse off after the past three years? Iraq has seen real political progress. Iraqis voted in three free elections in 2005, something rare in the Middle East. Yet hope has alternated with deep discouragement as Iraq has spiraled into sectarian violence between Sunni and Shi‘ite militias and insurgent groups. Iraq is now a training ground for al-Qaeda terrorists. There are so many deadly bombings and reprisals that the society can barely function, while American military casualties mount. General John Abizaid, testifying before House and Senate committees in mid-November, stated his conviction that Iraqi leaders still have the will and potential to pull the society together and resolve differences peacefully. But no one knows whether this can happen.

On the issue of proportional benefits, it can be said that the Bush administration engaged in wishful thinking rather than careful planning about the postwar future. It ignored the State Department’s prewar advice about Iraqi society and deployed an insufficient number of troops to secure the country. Those of us who supported the war on humanitarian grounds have reason to feel duped regarding the administration’s intentions.

My changed assessment indicates how vulnerable just war arguments are in the face of insufficient information, poor reasoning or corrupt reasoning. The lack of sufficient information may be excusable—it plagues all arguments about war. But poor reasoning, especially reasoning that refuses to listen to other arguments, is not excusable. And corrupt reasoning is reprehensible.

Americans are facing up to the misuses of the just war argument. Their judgment was expressed in the midterm elections. Because of that judgment, a more searching and more constructive public debate on the war is likely to take place. Many Republicans who retained their seats in Congress are sounding new notes. Democrats are likely to use their power to open debates and investigations. A bipartisan study group will put new ideas on the table. Just war theory is still relevant to this debate, for it can help the U.S. see where it went wrong and learn from its errors.