If what has happened to New Orleans had happened to Venice, the whole of Europe would now be calling for the greatest rebuilding project in history - to begins as swiftly as possible and at whatever the cost.
This urgency pervades the tone of almost every pronouncement in the United States today, only more so because underpinning the emotional urge to see New Orleans rise again from its toxic swamp is a belief in a quintessentially American capacity for personal and collective renewal.
These feelings are all the more intense for coinciding with the anniversary of 9/11: the square-jawed, patriotic determination of the firemen at Ground Zero is the posture every American public figure has been striving to adopt in the aftermath of Hurricane Katrina.
Politicians from George Bush downwards, aware of their shaming failure to provide an adequate immediate response to the crisis, seek to deflect criticism by banging drums for the idea of a splendid renaissance of the city. There are, after all, millions of votes to be rescued from this catastrophe, as well as thousands of homeless. Opinion polls suggest many ordinary Americans doubt the wisdom of rebuilding on the flooded site, but the only national figure to express that doubt, Dennis Hastert, the Republican speaker of the House of Representatives, was shouted down by Lousiana's Democrat senator, Mary Landrieu, and others.
But Hastert was right to raise the question, even if his timing was insensitive. The ancient world is scattered with lost cities - from Angkor in Cambodia to Leptis Magna, the great Roman settlement buried in the sands of present-day Libya - which were diminished and abandoned as a result of declining empires, shifting water courses and trade routes, and wars lost.
New Orleans's celebrated French Quarter and Garden District, built on higher ground, are storm-damaged but above water and clearly capable of revival as America's most atmospheric heritage site. But Greater New Orleans - a seething metropolis of half a million souls, more comparable to Italy's industrial slums of Mestre than to historic Venice across the lagoon - may be doomed to be the modern world's first lost city. For the poor black families who make up the bulk of its population, that may in the long run be the best thing that could have happened to them. The question of whether or not to rebuild is partly one of geography and engineering, and partly, more controversially, one of social planning.
It is also a question of money. Sums of more than $100bn (£54bn) have been bandied about. But whatever happens, all those citizens will have to be rehoused and reabsorbed into the economy somehow. And in the end, because so many are without savings or insurance cover for the assets lost, the federal government is going to have to help them out.
As the emotional level subsides along with the flood waters, the authorities will have to consider the options objectively, including the presently unthinkable one of allowing the city's ruined districts to be reclaimed by nature. They were, after all, claimed from nature in the first place by developers who drained the swamps between the Mississippi and Lake Pontchartrain over the past century. Parts of the city were built seven feet below sea level, protected by levees which few people believed could ever be breached. To rebuild close to the repaired levees, even if they are substantially stronger and better maintained than they were, will be a gamble on the future of the Gulf Coast's climate.
It is certain that there will be more hurricanes, perhaps even this season. What cannot be quantified is the risk that, in decades to come, global warming will make those hurricanes even more violent and destructive than Katrina. It is not a risk that the global insurance industry will be eager to take. Engineers with large federal budgets at their disposal will no doubt be able to devise better ways of predicting storms, controlling water flows, and protecting buildings. Some American commentators have already pointed out that no one questions the wisdom of continuing to develop San Francisco and Los Angeles, despite the geological certainty that the San Andreas fault will one day unleash another mighty earthquake.
But even so, the difficult question has to be asked: does it make sense to try to recreate the New Orleans that was there before - a city that was revealed by Katrina to be almost completely dysfunctional.
We have watched in horror the disintegration of civic society in New Orleans this past fortnight: the total absence of mutual trust and respect between citizens and authority, the prevalence of armed gangs, the impotence of the police and emergency services, the priority given to protecting property before helping those in extreme distress. We have learned that a city most of us thought of as a jazz-loving tourist destination contained 130,000 people living below the poverty line, had a murder rate 10 times the national average, and had a public school system in which almost half the schools were officially categorised as "academically unacceptable".
There are, or were, pockets of hope and excellence in the city's social infrastructure, such as Dillard University, a college originally for black students which dates its origins from 1869, and was last week evacuated to Shreveport, Louisiana. Even with its imperfections, America is still rightly admired by the poor of other continents as a land of opportunity. But the harsh truth is that the life chances of a child born to a poor black mother in New Orleans before the flood were about as low as they could be anywhere in the Western world, and little better than they would have been in Africa. It would be a less than marvellous achievement to rebuild a city that looked the same as before but offered nothing better.
Maybe the neighbourhoods can be recreated as mixed communities with better employment prospects and higher aspirations, as has happened, for example, in the once notorious Cabrini-Green housing projects of Chicago. Maybe those who have been dispersed to other cities across the southern states, having left so little behind (half of New Orleans's dilapidated housing stock was rented rather than owned), would be better off staying wherever they have come to rest and starting again. Maybe they should take a Greyhound bus to the other side of America and make a new life for themselves and their families as so many did in the Depression years. Maybe real-estate developers will see the percentage in building entire new towns for them on safer ground. If state governors and entrepreneurs need a model, they have only to look at the way low-tax, free-enterprise Hong Kong successfully accommodated hundreds of thousands of refugees from China in the 1970s.
All of this is easy to say, skating as it does over immense practical and human difficulties. But the debate needs opening up now, before New Orleans's fate is fixed by politicians over-anxious to win praise for a swift reconstruction which could turn out to be unsafe and socially misguided.
"Back and better as soon as humanly possible" is the slogan on Dillard University's website today. But can back really be better for the poor of New Orleans?Reuse content