Krugman and his wife, Robin Wells, at home with their cats, Doris Lessing and Albert Einstein. Photograph by Tina Barney

When it is cold at home, or he has a couple of weeks with nothing to do but write his Times column, or when something unexpectedly stressful happens, like winning the Nobel Prize, the Princeton economist Paul Krugman and his wife, Robin Wells, go to St. Croix. Here it is warm, and the days are longer, and the phone doesn’t ring much. Here they live in a one-bedroom condo they bought a few years ago, nothing fancy but right on the beach. The condo’s walls are yellow and blue, the furniture is made of wicker, there are pillows and seashells. There are tall, sprawling bougainvillea bushes along the side of the road.

“We first fell in love with St. John,” Krugman says. “It was New York lawyers who’d decided to give up on the whole thing and live on a houseboat and wear their gray ponytails.”

“But St. John went too upscale,” Wells says.

“Our complex is more Midwesterners. Retired car dealers and so on.”

The east end of St. Croix is something of a tourist spot, but the west end, where they decided to settle, is where the Crucians live, and it has a Jimmy Buffett feel to it that they like. In Frederiksted, the west end’s tiny town, there are a couple of coffee shops, a KFC, a Wendy’s, a few churches, a post office, and a promenade by the sea with concrete picnic tables. Not many people about. Farther out along the coast, there are beach bars with plastic chairs and Christmas lights, men with beards and very tanned middle-aged women sitting and smoking in the afternoon.

“The west end is where the whites who’ve gone native live,” Wells says. “They have a couple of beach bars with not very good blues and jazz bands. They were playing Neil Young as we went by the other night, and Paul said, ‘Boy, that was an awful rendition.’ ”

“It was Buffalo Springfield.”

“Yes, Springfield, O.K. I said, ‘Aging boomers, they love any rendition, no matter how bad.’ ”

Here Krugman wears the same shirt for days, a short-sleeved plaid cotton shirt, and bathing trunks. He sits in the room where they eat their breakfast, which has a long window open to the sea. He types at a tiny table that folds out of a closet, which requires him to sit more or less inside the closet, but this is helpful, because the light can be so bright in the room that it becomes blinding. If he turns his head, he can see the sky.

First thing when he wakes up, he checks out a few Web sites, and if he’s not writing his column that day he and Wells will go for a walk on the beach, or they will stroll into Frederiksted and have breakfast at Polly’s, a little coffee shop that serves iced lattes and pretty good egg burritos. If he is writing his column, he will start it on the morning of the day it’s due, and, if the spirit is with him, he will be done soon after lunch. When he has a draft, he gives it to Wells to edit. Early on, she edited a lot—she had, they felt, a better sense than he did of how to communicate economics to the layperson. (She is also an economist—they met when she was a postdoc at M.I.T. and he was teaching there.) But he’s much better at that now, and these days she focusses on making him less dry, less abstract, angrier. Recently, he gave her a draft of an article he’d done for Rolling Stone. He had written, “As Obama tries to deal with the crisis, he will get no help from Republican leaders,” and after this she inserted the sentence “Worse yet, he’ll get obstruction and lies.” Where he had written that the stimulus bill would at best “mitigate the slump, not cure it,” she crossed out that phrase and substituted “somewhat soften the economic hardship that we face for the next few years.” Here and there, she suggested things for him to add. “This would be a good place to flesh out the vehement objections from the G.O.P. and bankers to nationalization,” she wrote on page 9. “Show us all their huffing and puffing before you dismiss it as nonsense in the following graf.”

On the rare occasion when they disagree about something, she will be the one urging him to be more outraged or recalcitrant. She pushed him to denounce the filibuster. She wanted him to be more stubborn in holding out for the public option in the health-care bill. He spent a few sleepless nights wrestling with his conscience about that but ultimately decided that a flawed bill was so much better than no bill at all that he had to support it. “You can get beaten down,” he says. “When Robin and I started writing about health care, single payer was clearly the way to go. And then bit by bit you start saying, ‘O.K., you take what you can get.’ There’s a trap I’ve seen some people fall into—you let your vision of what should be get completely taken over by what appears possible right now—and that’s something I’m trying to avoid.”

In the late afternoon, they lie on beach loungers underneath a clump of sea-grape trees, facing the ocean. Krugman sips a piña colada through a straw and reads the galleys of a book about the financial crisis. They were thinking of having dinner at a place in town, but then they discovered that there was to be an Elvis impersonator singing there, so they decided to go to the Sunset Grill, where the stereo is playing Wings. It’s getting buggy on the beach, and Wells hands Krugman a can of Off. The tide is coming in. Krugman puts his book down, eases himself out of his lounger, and, still wearing his hat and sunglasses, wades cautiously into the sea.

In his columns, Krugman is belligerently, obsessively political, but this aspect of his personality is actually a recent development. His parents were New Deal liberals, but they weren’t especially interested in politics. In his academic work, Krugman focussed mostly on subjects with little political salience. During the eighties, he thought that supply-side economics was stupid, but he didn’t think that much about it. Unlike Wells, who was so upset when Reagan was elected that she moved to England, Krugman found Reagan comical rather than evil. “I had very little sense of what was at stake in the tax issues,” he says. “I was into career-building at that point and not that concerned.” He worked for Reagan on the staff of the Council of Economic Advisers for a year, but even that didn’t get him thinking about politics. “I feel now like I was sleepwalking through the twenty years before 2000,” he says. “I knew that there was a right-left division, I had a pretty good sense that people like Dick Armey were not good to have rational discussion with, but I didn’t really have a sense of how deep the divide went.”

For the first twenty years of Krugman’s adult life, his world was divided not into left and right but into smart and stupid. “The great lesson was the low level of discussion,” he says of his time in Washington. “The then Secretary of the Treasury”—Donald Regan—“was not that bright, and you could have angry exchanges where neither side understood the policy.” Krugman was buoyed and protected in his youth by an intellectual snobbery so robust that distractions or snobberies of other sorts didn’t stand a chance. “When I was twenty-eight, I wouldn’t have had the time of day for some senator or other,” he says.