(FORTUNE Magazine) – We Americans like to boast about our economic turnaround in the '90s, but you could argue that England--where I've spent the past few weeks--is the real comeback story of the advanced world. When I first started going there regularly in the early '80s, London was a shabby and depressed city, and the country's old industrial regions were a Full Monty-esque wasteland of closing factories and unemployment lines. These days, however, London positively buzzes with prosperity and with the multilingual chatter of thousands of young Europeans--French especially--who have crossed the Channel in search of the jobs they can no longer find at home. How this turnaround was achieved is a fascinating question; whether the new Labour government can sustain it is another.

But I'm not going to try answering either question, because I've been thinking about food. Marcel Proust I'm not (what the hell is a madeleine, anyway?), but the change in English eating habits is enough to get even an economist meditating on life, the universe, and the nature of consumer society.

For someone who remembers the old days, the food is the most startling thing about modern England. English food used to be deservedly famous for its awfulness--greasy fish and chips, gelatinous pork pies, and dishwater coffee. Now it is not only easy to do much better, but traditionally terrible English meals have even become hard to find. What happened?

Maybe the first question is how English cooking got to be so bad in the first place. A good guess is that the country's early industrialization and urbanization was the culprit. Millions of people moved rapidly off the land and away from access to traditional ingredients. Worse, they did so at a time when the technology of urban food supply was still primitive: Victorian London already had well over a million people, but most of its food came in by horse-drawn barge. And so ordinary people, and even the middle classes, were forced into a cuisine based on canned goods (mushy peas!), preserved meats (hence those pies), and root vegetables that didn't need refrigeration (e.g. potatoes, which explain the chips).

But why did the food stay so bad after refrigerated railroad cars and ships, frozen foods (better than canned, anyway), and eventually air-freight deliveries of fresh fish and vegetables had become available? Now we're talking about economics--and about the limits of conventional economic theory. For the answer is surely that by the time it became possible for urban Britons to eat decently, they no longer knew the difference. The appreciation of good food is, quite literally, an acquired taste--but because your typical Englishman, circa, say, 1975, had never had a really good meal, he didn't demand one. And because consumers didn't demand good food, they didn't get it. Even then there were surely some people who would have liked better, just not enough to provide a critical mass.

And then things changed. Partly this may have been the result of immigration. (Although earlier waves of immigrants simply adapted to English standards--I remember visiting one fairly expensive London Italian restaurant in 1983 that advised diners to call in advance if they wanted their pasta freshly cooked.) Growing affluence and the overseas vacations it made possible may have been more important--how can you keep them eating bangers once they've had foie gras? But at a certain point the process became self-reinforcing: Enough people knew what good food tasted like that stores and restaurants began providing it--and that allowed even more people to acquire civilized taste buds.

So what does all this have to do with economics? Well, the whole point of a market system is supposed to be that it serves consumers, providing us with what we want and thereby maximizing our collective welfare. But the history of English food suggests that even on so basic a matter as eating, a free-market economy can get trapped for an extended period in a bad equilibrium in which good things are not demanded because they have never been supplied, and are not supplied because not enough people demand them.

And conversely, a good equilibrium may unravel. Suppose a country with fine food is invaded by purveyors of a cheap cuisine that caters to cruder tastes. You may say that people have the right to eat what they want, but by thinning the market for traditional fare, their choices may make it harder to find--and thus harder to learn to appreciate--and everyone may end up worse off. The English are often amused by the hysteria of their nearest neighbors, who are terrified by the spread of doughnuts at the expense of croissants. Great was the mirth when the horrified French realized that McDonald's was the official food of the World Cup. But France's concern is not entirely silly. (Silly, yes, but not entirely so.)

Compared with ethnic cleansing in Kosovo and the plunging yen, such issues are small potatoes. But they do provide, well, frites for thought.

PAUL KRUGMAN is a professor of economics at the Massachusetts Institute of Technology.