Ten years after "shock and awe", the reasons behind the invasion of Iraq have yet to be satisfactorily explained.
Journalists, scholars, soldiers, and ideologues have all toiled for answers. Oil, imperialism, militarism, democracy, Israel and free markets have been offered as explanations.
Some of these are mutually exclusive, and they all seem to enlighten less than they satisfy the innate human need for simplification. In the hands of academics, on the other hand, explanations inevitably turn "complex" (a ubiquitous marker that separates man from mandarin).
To say that the causes of the Iraq war are easy to explain is not to say that they are simple. But the lack of simplicity does not imply indeterminacy, either. The reality may be complex but is decidedly explicable.
One does not have to subscribe to the Tolstoyan notion of history - an inscrutable force, without agents, predestined and with infinite causes - to accept that a phenomenon as complicated as a war can have multiple causes. Iraq had many. Each of the aforementioned played some part in the calculus of decision makers; but they are not equally significant. Key actors were not driven by the same motives, nor did they reach their decisions simultaneously.
George W Bush, Dick Cheney and Donald Rumsfeld prosecuted the war, but the neoconservatives conceived it. September 11, 2001 was the catalyst, but the neoconservatives helped instrumentalise it.
The neoconservatives' interest in toppling Iraq preceded that of Mr Bush, Mr Cheney or Mr Rumsfeld. Regime change had been official US policy since 1998 and unofficial policy even longer. But the means were understood to be diplomatic pressure, economic strangulation and covert action - not invasion and occupation.
Mr Bush started receiving briefings on the subject only in the run-up to his presidential campaign. The Vulcans - the foreign policy study group advising Bush - were led by Condoleezza Rice, who in a position paper for Foreign Affairs had argued that Iraq's military power was "severely weakened" and that the US could live with even a nuclear Iraq.
Mr Cheney had spent the 1990s complaining about the "sanctions-happy" policy of the Clinton administration. He also headed USA*Engage, an industry consortium lobbying for the repeal of the Iraq Libya Sanctions Act of 1996, an Israel lobby confection.
Mr Rumsfeld had shown little interest in Iraq in the decade and half between his infamous handshake with Saddam Hussein and his signing of a letter drafted by the neoconservative-led Project for the New American Century. By the winter of 2001, however, Mr Bush, Mr Cheney and Mr Rumsfeld were all persuaded of the war's necessity.
September 11 partly explains the change in mood. But it did not make war inevitable. There was public opinion to be manipulated, there were bureaucratic hurdles to be overcome. Iraq had to be put on the agenda, presented as an imminent threat. Only then could a pre-emptive war be justified. For this, the conjunction of Iraq's alleged ties to Al Qaeda and its possession of WMDs was necessary. Together they would constitute a threat to make the search for further evidence an exercise in punctilious irresponsibility. As the White House talking point had it, the smoking gun might turn out to be a mushroom cloud.
A survey of the stories appearing in the immediate aftermath of September 11, linking Iraq to the attacks, reveals an almost exclusively neoconservative provenance.
Most of the stories I have seen cite unsubstantiated claims by one person, neocon ideologue Laurie Mylroie. Her theories were aggressively promoted inside government by Paul Wolfowitz, who also assigned his protégé Douglas Feith to find material to support Ms Mylroie's claims.
Mr Feith established two ad hoc offices - the Policy Counterterrorism Evaluation Group and the Office of Special Plans - to manufacture the Iraq-Al Qaeda connection and evidence of Iraq's alleged WMDs. He was assisted by exiles and con-men of the Iraqi National Congress and, more significantly in my view, by The New York Times correspondent Judith Miller, co-author with Ms Mylroie of a 1991 book on Iraq.
Meanwhile, neocon linchpin Richard Perle arranged for Mr Cheney to be personally briefed on multiple occasions by orientalist doyen Bernard Lewis, who assured the revanchist vice president that the only language Arabs understood was force. "Shock and awe" was the natural corollary.
But what of oil? For all its prima facie plausibility, the "war-for-oil" thesis seems to satisfy the test neither of logic nor evidence. In 2003, Iraq wasn't withholding its oil, it was being embargoed. The oil companies had spent a decade lobbying not for war, but for lifting of the sanctions. Minds might have changed by 2003, but there were many means available, less costly and more predictable than war.
At least three times in the six months leading up to war, Saddam Hussein had made desperate efforts to preserve his power by offering the US privileged access to Iraqi oil. Oil companies got on the bandwagon only after war had become inevitable, though not without trepidation. They all feared the destabilisation that might follow.
For Mr Cheney and Mr Rumsfeld, the primary motivation was not oil, but the war's demonstrative effect - a sanguine assertion of US military power, to intimidate any rogue who might consider harming the US by handing WMDs to terrorists. For Bush, according to most insiders, the chief motor was his simplistic, messianic belief in fighting an "evil" regime - a regime that had earlier bedevilled his father. He was also flattered by advisers and Iraqi exiles into embracing his new role as a leader of men, liberator of peoples, bestower of democracy.
It is possible that Mr Bush, Mr Cheney and Mr Rumsfeld would have decided to invade Iraq without neoconservative encouragement. But without their help it was unlikely that the war party could have overcome the resistance of the hesitant military, intelligence and diplomatic establishments. In their social cohesion, ideological coherence and dominance of the national security apparatus, and with the resources and institutional support of the wider Israel lobby, the neoconservatives had advantages unavailable to any other faction.
In the long paper trail the neoconservatives left over the previous decade - particularly the two policy papers Mr Perle, Mr Feith and David Wurmser wrote for Benjamin Netanyahu's first government - ideas that Mr Wurmser later elaborated in his 1998 book Tyranny's Ally - these motivations are unequivocally stated.
Neoconservatism has its ideological roots in revisionist Zionism, and so it gives Israel high priority. For the neocons, the war was desirable because it would fragment a potentially powerful Arab state and leave Israel's real nemesis, Iran, more vulnerable. It would also leave the Palestinians more isolated and amenable to compromise. For them the road to Jerusalem ran through Baghdad.
Nearly a million Iraqi dead later, with more than US$3trillion (Dh11trillion) lost and 5,000 servicemen killed, it isn't always clear if the US has learnt any lessons. In the aftermath of Vietnam, there was much soul-searching; Iraq has occasioned little. The rhetoric is still belligerent and the enthusiasm for war only marginally diminished.
Iraq seemed improbable until it happened. In his memoir, Mr Feith laments that his attempts to place Iraq in the administration's crosshairs were meeting with derision as late as the summer of 2001. September 11 changed all that.
War with Iran likewise seems unlikely today; and this has encouraged US politicians to engage in brinkmanship with Iran without fearing consequences. All of this could quickly change should a "catalysing event - a new Pearl Harbor" upset the equilibrium.
If there is one lesson to be learnt from Iraq, it is that history is contingent and ideas have consequences. Only inertia responds to human will. With its preponderance of lethal power, the US has a responsibility to avoid giving fortune hostages.
Muhammad Idrees Ahmad is a sociologist based in Scotland and the author of a forthcoming book on the Iraq war. He edits Pulsemedia.org