In war and in politics unexamined axioms are always dangerous. That much we learnt from 2003. The axiom driving policy then was that Saddam Hussein had WMDs. On that unquestioned assumption, all the debate rested. And yet the axiom was false.

Today a similar unquestioned axiom is driving the debate about whether to stay in Iraq or leave. The axiom is that leaving Iraq would be a disaster for the security of the West. Here’s how President George Bush put it last Wednesday night: “To step back now would force a collapse of the Iraqi government, tear the country apart and result in mass killings on an unimaginable scale. Such a scenario would result in our troops being forced to stay in Iraq even longer and confront an enemy that is even more lethal.”

The fundamental question we have to ask right now is: how true is this? On the face of it the president has a very strong point. Withdrawal would indeed be likely to prompt a massive blood-letting in Iraq. It would give the Sunni-Shi’ite civil war far more oxygen and almost certainly provoke the Sunni powers, particularly Egypt and Saudi Arabia, to intervene financially or militarily in defence of Iraq’s outnumbered Sunni minority.

It would mean Iran emerging as a Shi’ite superpower in the region, with a strong presence in Iraq, Syria and Lebanon further intensifying the sense of Sunni beleaguerment and anger. We could see violence along the ancient Sunni-Shi’ite fault line sucking in much of the region, with its many fragile regimes. The consequences could be soaring oil prices, and any number of unforeseen disasters. After all, ask yourself: how many pleasant surprises come out of the Middle East? And yet the alternative — an indefinite entanglement with the pathologies of Iraq — prompts the question of whether there’s anything in this nightmare scenario that could be advantageous for the West. Is there a constructive argument for leaving? That’s the alternative scenario worth pondering.

Here’s how the counterintuitive argument would run. From 9/11 onwards the West’s war on terror has essentially followed the ideological narrative of Al-Qaeda and Osama Bin Laden: this is a war between Islam and the West. President Bush’s dismal war strategy has only intensified that narrative, and that storyline is easily the most powerful recruitment device for Islamist terrorists in the West.

But if America withdrew from Iraq and a Sunni-Shi’ite war took off, the narrative of the long war would inevitably change. It would go from Islam versus the West to Islam versus itself. Escalating conflict in the Arab Muslim world would only be fully explicable in terms of the Sunni-Shi’ite split.

Instantly, Sunni Al-Qaeda would have a serious enemy close at hand: Shi’ite Iran. Think of this not as a “divide and conquer” strategy so much as a “divide and get out of the way” strategy. And with deft handling it could conceivably reap dividends in the long run.

Wars, after all, are not just about guns and military action. They are also about ideas and ideology. Long wars, especially, are won by those who gain control of the narrative. The West won the cold war when it became understood globally as a battle between totalitarianism and freedom. Defining the conflict that way helped a great deal towards winning it, and in retrospect the Helsinki accords which publicly endorsed that narrative were the beginning of the end for the Soviet Union.

Similarly, redefining the war on terror as essentially the product of ancient feuds within Islam immediately shifts the argument onto terrain favourable to the West. For the first time in five years, it takes the narrative out of Bin Laden’s hands.

It also has the added benefit of being true. Al-Qaeda’s primary foes have always been Arab regimes not in accordance with extreme fundamentalist Wahhabist theology. But that theology is also full of contempt for those regarded by Al-Qaeda and most Sunnis as heretics: the Shi’ites of Iran.

We are learning in Iraq not to underestimate the power of this mutual hatred. The loathing of Muslims for other Muslims in the Middle East today is as deep as the loathing of Christians for other Christians once was in Europe. For Sunni versus Shi’ite, think Protestant versus Catholic. For 2007, think 1557.

Freud’s term for the passionate hating of people very like oneself — but different in some minor degree — was the “narcissism of small differences”. The West has a chance to exploit that Muslim narcissism for our own purposes — and for the sake of moderate Muslims across the world.

Or look at this another way: what is the greatest weakness of our enemy? The answer is fanaticism. It was fanaticism that prompted Bin Laden to attack on 9/11 before he had access to WMDs. He struck too soon because he couldn’t help himself. His rage forces him to make mistakes. The same went for Abu Musab al-Zarqawi, who alienated all of Jordan by bombing a wedding and who even prompted Bin Laden to worry about killing too many Muslims in Iraq.

Al-Qaeda hates the West but its main beef is with fellow Muslims who are heretics and traitors. The fanatics have certainly killed far more Muslims than non-Muslims over the years.

So why not let them hang themselves by this rope? By leaving Iraq, America could create a dangerous civil war that nonetheless has huge propaganda potential for changing the entire game of this larger war. It takes the West much further out of the picture and focuses the mind where it truly belongs: on current Muslim pathologies, paranoia and self-hatred. We can still prove our pro-reform bona fides by concentrating on Afghanistan, where we still have a chance to turn things around. And we also give Iran a big headache in grappling with the chaos on its border.

The other likely result of a Sunni-Shi’ite war is serious damage to the world’s oil supply. But isn’t that just what the West needs? Don’t we desperately need to wean ourselves off oil — and wouldn’t $100 a barrel be the best way to accelerate that? I’m not saying that leaving a civil war in Iraq is not dangerous. But so is staying. And the upsides of leaving haven’t been fully thought through yet, so let’s think them through, shall we? My fear is that Bush has not thought this through. There is no plan B because his rigid, incurious mind doesn’t have the dexterity to entertain it. The fundamentalist psyche doesn’t like paradox or nuance. But in dealing with this complex and metastasising problem, paradox and nuance and ruthless self-interest are indispensable.

This surely is the real conservative insight: that ideology must never trump reality, that new scenarios need new thinking, that in every crisis there is an opportunity. Currently the axiom that withdrawal is unthinkable is impeding our ability to think of new directions and new strategies. But we desperately need to think outside our comfort zone. Flexibility is not an enemy in wartime. In fact in this war our very survival may even depend on it.

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