As a student, I once sat in a Rome trattoria and watched an American couple work themselves into a head-shaking lather at the management's inability to supply them with a bottle of ketchup. More than a quarter-century later, reporting from the United States for a British newspaper, I have this nagging feeling that in a world of increasingly shared values, Europeans and Americans still don't get it about one another.

This is not to say that the values we share, or the aims for which we have sometimes fought as allies, cannot or do not ultimately transcend things like the mutual disbelief in that trattoria over the bottle of ketchup. By and large, and on the big issues, they do.

But on the more elusive everyday questions that make up most of life--from the way we think about food, to the way we think about health and violence and perhaps even science--it is striking how often Americans and Europeans can find themselves, not so much at odds, as simply looking down different ends of the telescope.

"Those who only know one country, know no country," social scientist Seymour Martin Lipset wrote in his study of American exceptionalism, and it is remarkable how tenaciously true this judgment remains, even amid a process of economic and political globalization, which tries to persuade us that national differences are old-fashioned and that to draw attention to them is to commit a form of modern apostasy.

It is no accident that the issue of food has already reared its head. Over the past few months, while Europeans and Americans have stood more or less shoulder to shoulder in the fight for human rights and self-determination in the Balkans, these same allies have simultaneously been engaged in an increasingly acrimonious argument over what we consume.

Most Americans give barely a moment's thought to the genetic modifications that have been applied to the food of which they eat so much. Yet the hormone-enhanced steaks and the biotech-improved vegetables that to Americans seem almost routine have roused European populations to genuine anger and protest this year. So strong have been the feelings in Britain, for instance, that Tony Blair's government, normally respectful of public opinion, was forced to retreat, under attack from all parties, from its perceived indifference to genetically modified food. Meanwhile, throughout continental Europe, especially in Germany and the Netherlands, where Green politics are rooted and strong, protesters have ensured that the issue of importing genetically modified foods--much less the foods themselves--is not even on the table, thus forcing talk of a transatlantic trade war.

Part of this argument is simply good old-fashioned political posturing, with governments on both sides of the ocean squaring off on behalf of their agricultural interest groups before hammering out the latest compromise, over cold towels and hot coffee, in a familiar all-night bargaining session.

But it would be a mistake to see this dispute as merely routine political bravado. From the earliest times, human societies were defined by their food rituals, and food remains to this day not merely the staff of life but the very stuff of cultural identity and difference. For two centuries, French life has marched to the dictates of Revolutionary-era laws governing the making and the price of bread. In Germany, the nation's self-image is intimately bound up in the ancient purity legislation in the brewing industry. Spain is inseparable, in its own mind, from its ancient maritime fishing rights. Even in Britain, a nation not celebrated for its food, any threat to daily bottled milk delivery and the size of a pint beer glass can touch deep ancestral chords.

The outcry in Europe against the genetically modified products of the American food industry may seem a bit of a cheap chauvinistic shot at Uncle Sam, but it is also about something more elusive but endemic. Europeans still like to think of themselves as close to the soil--as farmers who just happen to have lived in cities for generations. Food connects Europeans with their history and their sense of themselves. American food, especially the meat that goes in the ubiquitous burger, reminds Europeans of what they have lost, even if the sense of loss is sometimes heavily sauced with hypocrisy. As political scientist Benjamin Barber has put it, McWorld serves up unintended cultural jihads.

If this implies that the differences between Europeans and Americans are in some fundamental sense political, then so they are. It would be ridiculous to deny that these disputes have nothing to do with European resentment toward American transcendence, or with Europe's consequent inferiority complex. But these differences are also cultural, in a nonpolitical sense.

To those who doubt that we are what we eat, compare the experience of restaurant dining on either side of the Atlantic. To a European in an American restaurant, two things are particularly striking. First, there is the remorseless insistence on choice, more choice and still more choice, exemplified by the multiple-choice experience that confronts anyone naive enough to think that Starbucks will provide a mere cup of coffee. Second, there is the opulent generosity of American servings, which embody the belief that this is a world of infinite resources, offering up limitless horizons of fulfillment and in which the idea--let alone the experience--of rationing is unknown and even suspect.

In much of Europe, to this day, a restaurant experience offers the precise reverse. You get what you are given--table d'hte--and whether you are Oliver Twist or an American tourist, you don't ask for more or for ketchup. Europe remains a continent in which there is a right way and a wrong way for everything to do with food, from growing to preparation to eating. In the more class-divided societies, such as Britain, even knowing which fork to use was until recently a secret preserved by the rich few from the poor and middling many.

Food is just one human activity that stands as a metaphor for wider differences. In Europe, the rules are obeyed. In America, authority is disdained. The results can be seen in phenomena as varied as the crime rate and the level of voter participation in elections. By and large, if a European political leader says that the nation is at war, then the nation is at war. If the U.S. president wants to go to war, Congress, at least theoretically, has first to agree.

We should understand the serious implications of these wide-ranging differences. They apply to guns just as much as to butter. To many Europeans, indeed, nothing is more genuinely incomprehensible about modern America than the desire of tens of millions of its citizens to own guns and the insistence of a vast swath of American society that gun ownership is a sacred right that cannot be reformed in the light of recurrent tragic experience.

Americans may point, with irresistible justice, to the continuing violence of 20th century Europe and, less gruesomely, to the strength of the animal-hunting culture everywhere from Ireland to the Urals. Anyone who has ever been in Italy at the start of bird-shooting season can legitimately say that trigger-happy madness is not an exclusively American condition.

What causes European disbelief, though, is that America is so uncharacteristically unwilling to confront the problem rationally. Hunting as well as sports shooting remain popular even in Britain, but that did not prevent a nationwide handgun ban from being introduced there with near-universal support following the school shootings in Dunblane, Scotland, in 1996. To Europeans, America's fixation with guns is a source of both fascination and horror. The recent killings in Littleton and Atlanta now define this country in European eyes to a degree that ought to shock Americans.

And yet, like many of the other stereotypes of America on which Europeans are raised, the gun-happy stereotype is far from accurate. There are far too many guns in America, and far too much shooting, and the gun laws are undoubtedly far too lax. But what Europeans do not grasp is that guns and shooting do not really define day-to-day American life and that one can go for years without ever seeing a gun, let alone being the victim of one. Europeans who come to the U.S. and step out of their hotels half expecting to become shooting victims find very quickly that they got it wrong.

But it is not just Europeans who worry about the "wrong" things or who journey across the Atlantic in a mood of misplaced fear. Periodically, Americans decide en masse against traveling to Europe on account of threats from Arab or Irish terrorism that pass all but unnoticed there. In both cases, the reality is that visitors to Europe are much more likely to get hurt in a traffic accident than they are by a bullet or a bomb.

Every society has its distinctive collective worries, and none tell you more about the particularity of that society than its medical preoccupations. Germans famously worry more than most about the regularity of their bowel movements. The French, no less characteristically, focus their anxiety on the liver and digestion. Englishmen and women, especially from the upper classes, were brought up to regard such things as signs of feebleness, which could be overcome by character-building and regular cold showers.

The supreme particularity of the American health obsession is fear of the loss of youth. No other nation shares this preoccupation to such a degree. Europeans see this expressed in Americans' attention to exercise, their love of magic potions and, above all, in the widespread use of cosmetic surgery. And if television medical ads are a good guide to the ailments that worry modern Americans most, then, to this British eye at least, the United States is inhabited by a population consumed by the problems of acid reflux and martyrs to the perils of overactive bladder syndrome. Perhaps this really is so, in which case, one is tempted to suggest that Americans should cut down on the pizza and coffee rather than spend even more on remedies, but the point is that these are very distinctive obsessions: Acid reflux is as unknown in France as the French crisis of the liver is in America.

Such differences can be treated as nothing more than amusing splashes of local color. But, in my opinion, they are evidence of something more lasting and more significant. At a time when economists, pundits and presidents are telling us that we all inhabit a new and gloriously convergent world, these differences offer a counterpoint to oversimplification. The pundits are not wrong about the fact that the world is changing, or even about the way in which it is changing, but they are too casual about understanding and appreciating the ways in which parts of the world refuse to change, will not change and should not be expected to change. When life and death and liberty are at stake, we all stand together. The rest of the time, we should get on with being different and stop worrying about it.

Martin Kettle is the Washington correspondent of London's Guardian newspaper.