Why did America go to war in Iraq? It is extraordinary that more than four years into the conflict, this is still a question without a proper answer. Was it really all about "weapons of mass destruction"? Was the real motive a grand plan to remake the Middle East? Did America simply feel the need for a massive demonstration of its power, in the wake of the attacks of September 11 2001? Or was this a "war for oil"?

My guess is that the second motive, remaking the Middle East, was the most important - and that all the other considerations played a part as well. But I also think there was a fifth element - not so much a motive as a state of mind.