Joseph Boudreaux, 2nd Chief of the Golden Eagles Mardi Gras Indians. (Erika Goldring/Getty Images)

 Adam B. Kushner is the editor of Outlook.

When Hurricane Katrina annihilated my home town, it also seemed to extinguish a strain of American optimism. Suddenly, people wondered aloud whether New Orleans should be rebuilt at all. It would cost a fortune and put people back in harm’s way. “That doesn’t make sense to me,” said Dennis Hastert, who was then speaker of the House. With sea levels rising, how long would it be until the whole city was underwater anyway? “A lot of that place could be bulldozed,” he concluded.

This vile strain of thinking was surprisingly common. In an essay titled “Don’t Refloat,” Slate held that “it would be a mistake to raise the American Atlantis. It’s gone.” In this newspaper, a Columbia University geophysicist pointed out that “10 feet below sea level and sinking is not safe.” Even now, a decade into a successful recovery, the argument lives on. Rep. Marcy Kaptur (D-Ohio) rued in May that nobody had listened to her when she recommended leaving the soused Ninth Ward “open for agriculture, so that when you get another big threat from the ocean, you won’t harm as many people.”

Today, this argument is clearly buffoonish, but I understand why people made it. Because, after the storm, I made it myself.

I was one of the pessimists who thought flood-prone neighborhoods shouldn’t be rebuilt, and I told anyone who would listen — in print at the New Republic (where I was a young editor at the time), on television talk shows and even in conversations with my childhood friends, some of whom divorced me over it. Like the others, I thought I was telling an unpopular but necessary truth. I knew that natives wouldn’t trust spendthrift Republican politicians, outside journalists and academics to look out for our best interest. The truth needed to come from an insider, and I decided that insider was me.

Paeans to New Orleans tend to take a sentimental tone: It’s colorful, musical, weird, delicious, diverse, relaxed. All true. But the horror of Katrina, which left hundreds of thousands homeless and took nearly 2,000 lives, seemed to demand that we overcome sentimentality. With so much at stake, skeptics like me thought instead about utility: What is the safest thing for the most people?

This was profoundly wrong. New Orleans has no place in a cost-benefit analysis, because what it offers — what it adds to America — cannot be counted. Its value is avowedly sentimental, and it was folly to believe that a culture could be weighed in this way. After 18 years there, I should have known that myself. The reason I didn’t helps explain why others couldn’t either.

I loved New Orleans growing up. It bred in me a snobbery about food, a love of music and the urge to dance everywhere, all the time, as people there do. I thought I grasped what gives the city its celebrated character: the odd alchemy of European Catholic settlers, freed slaves and the African traditions they preserved, anti-American pirates, Acadian (Cajun) refugees, Creole tradesmen and later waves of immigrants from Germany, Croatia, Ireland, Italy and Vietnam. I had a hazy understanding that strands from each of these cultures — their food, their music, their architecture, their language — wove together to make New Orleans unique.

Yet in a city built from the sum of its parts, I truly knew just one part: the white, wealthy avenues of my youth. I managed to avoid learning much about several neighborhoods, especially the mostly poor, mostly black ones that Katrina would hit hardest. Perhaps it was inevitable, then, that I saw dysfunction all around me instead of beauty, echoing the concerns of my set. The politics were corrupt. The per-capita murder rate was, at points during my childhood, the nation’s highest. Certain powerful white enclaves remained defiantly racist, and, in a city that was two-thirds black, Mardi Gras parades weren’t fully desegregated until 1992. The public school system, from which I graduated, was a scandal. Inequality never stopped growing. And apart from the tourism and shipping industries, the city had no broad-based economy. (After a dalliance with Louisiana in the 1980s, oil companies relocated their headquarters to Texas.) I knew from a young age that if I wanted to dream big, I’d have to leave. I moved away for college, sure I understood the place, and haven’t lived there since.

So when Katrina struck, I landed, heartbroken and searching, upon these conclusions: Katrina was a mid-level (Category 3) hurricane that washed over a mostly empty city, resulting in a man-made disaster thanks to levees that weren’t up to code. When they breached, New Orleans — which, topographically, resembles a bowl — filled slowly over the course of a day, allowing most hangers-on to plot their escape to higher ground. The death toll could have been so, so much worse.

The real freak superstorm — the “big one” meteorologists have been predicting — will be different. It will plow into the frayed wetlands, pushing a 25-foot surge of Gulf water over (or through) the levees and into the topographical bowl, drowning those beneath the waterline. When it lands, the 100,000 residents who have no access to a car won’t be able to hunker down or swim to higher ground. They could die in a catastrophe on par with Nagasaki.

The only sliver of hope to protect the city is an engineering moonshot: Refurbish the marshlands of southern Louisiana. These once sapped the energy from tropical storms and slowed their surges, but thanks to shipping lanes and oil-and-gas extraction canals carved through them, saltwater is washing them away. More than 2,000 square miles (the equivalent of Delaware) have eroded in my parents’ lifetime, and another football field’s worth vanishes every hour. To reverse the destruction, coastal scientists have a scheme to collect Mississippi River sediment that currently flushes out to the ocean, pipe it to the swamp, plug the gaps and shore up what’s left. They estimate that this work would cost $100 billion. It’s a hopeless request in a deficit-allergic age.

Therefore, I decided it would be dangerous and negligent to rebuild the neighborhoods that remained vulnerable. How, knowing what we now know, could we put people back in harm’s way? Clear thinking, I saw, could save lives.

Katrina, though, was an attack on my ignorance. Even as I wrote off the future of my home town for the good of its people, I read stories about the storm’s impact that made me realize that I had only rarely been to New Orleans East, an African American neighborhood, or partied in Treme, where so much inventive music was born from the mixture of peoples in close quarters. My first visit to the Lower Ninth Ward was three months after the storm.

Slowly, I began making up for lost time. I built myself a New Orleans syllabus. I followed Mardi Gras Indians, the African American revelers who pay tribute to Native Americans (who fought with the Union for abolition) by sewing elaborate feathered costumes from scratch each year and dancing off against each other. In 2007, led by a funky brass band and hawkers pulling coolers full of Abita beer, I danced down the street for the first time in a second line, a kind of weekly parade put on by “social aid and pleasure clubs” — clubs that began 150 years ago as community insurance for freed blacks who couldn’t afford the extravagant costs of funerals for their loved ones. White and black New Orleanians have spent decades enjoying these exuberant rituals together. Yet I was just discovering them.

On every trip home to visit my parents, I drove into areas that had played crucial roles in the city’s history. I asked a lot of questions, even when I thought I knew the answers; New Orleanians answered them eagerly and bought me drinks. (More than once, I was asked a deflating question: “Where are you from?”) I reported. I ate at unassuming neighborhood restaurants that had spent generations honing the recipes that made them famous. At clubs in Treme, I finally appreciated how much local geography shaped local culture — how the drumming rhythms of nearby Congo Square, where slaves were permitted to maintain African traditions, infused the ragtime played in Storyville brothels that became early jazz. I read history, anthropology, musicology, geography and journalism.

It would be wrong to say I discovered anything surprising. It was more like giving form and color to the rough sketches I’d spent a lifetime looking at. But only when the entire composition had come into view could I see clearly what it meant. New Orleans was an entire city devoted to the value I professed to hold most dear: joie de vivre.

And in New Orleans — unlike in the Potemkin parties of Las Vegas or Key West — it emerges organically and is felt universally. YouTube overflows with videos of spontaneous dance parties on the street, in the airport, starring cops. It’s absurdly easy to find a transcendent meal at the dive on a random corner. The celebrations and even the frustrations (many of which have abated in the years since the storm) serve as a collective bonding experience: We’re all in this together. Strangers habitually start conversations with each other, even across otherwise rigid racial or economic barriers. The only other time I’ve felt anything like it was living in New York, during a fleeting month of esprit de corps after the Sept. 11 attacks.

This spirit of laissez les bon temps rouler is what the rest of us say we want. How many books and articles and TED talks instruct us to slow down, to keep perspective, to focus on the things we love, to enjoy life before it ends? New Orleans is an entire city dedicated to those ideas. A place like that should be protected at any cost — even $100 billion — not closed down for the sake of some imagined greater good. The politicians and geophysicists couldn’t see that because they weren’t there, at least not in any meaningful way.

As an animating principle, joie de vivre has its drawbacks, and they help explain the city’s dysfunction. A major metropolis devoted to the good life cannot be a place of surpassing efficiency. But why couldn’t I see that flaw as the tolerable side effect of a miraculous, serendipitous, singular creation?

Some knowledge you do not simply absorb; you have to work for it. I had known my New Orleans but not the New Orleans. I was not really an insider. And if that was true of someone who had spent 18 years there, it was much more true of the armchair policymakers I had joined in dismissing the city’s future. Thankfully, our plan did not prevail — and never really even got a hearing. The intuitive response (fight back, rebuild) was always the best.

Because I had not fully known it, I could not see that the culture of New Orleans might exist beyond quantifiable valuation. Perhaps the formula “cost of abandonment < cost of further death” makes sense in other, less-distinctive places, such as the subdivisions in Western states now under threat from forest fires. But surely it makes no sense in a place with an ancient, unique spirit. Joie de vivre does not answer to the cause of utility.

This was a disturbing realization for a believer in science and data. The era of “Nudge” and behavioral economics has promised to deliver more technocratic policymaking. But intelligence is not wisdom. My belated New Orleans education forced me to swallow an impossible, and yet an inevitable, fact: the spiritual, the musical, the mystical side of human relations. Sometimes what is important cannot be seen, only felt.

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