THE UNITED STATES is the most open of democracies, but openness may now be a luxury the United States can no longer afford in such large doses.

At its simplest, this openness is demonstrated by the unrestrained freedom of elected representatives to inquire into whatever area of government they wish, from the details of trade agreements to the details of CIA covert actions. In fact, all American citizens consider themselves licensed participants even at the highest levels of government.

To Europeans, the spectacle of Congress investigating and publishing the secrets of the CIA, America's secret service, is astonishing. Part of that astonishment comes from a misunderstanding of the sources of the American system's strength: There are good reasons why Americans like openness. In the old countries of Europe, where the state has its own mystique, power deals in secret. But in the fiercely competitive democratic arena of American politics, publicity and drama are central to politics -- and drive the Congress and the executive branch to seek public support for often-conflicting policies.

Individual rights and duties are also far more important in American political life than in European. Only in special circumstances can state secrets be as important as the prerogatives of the individual American. Many Europeans think exactly the opposite. In 1986, for example, when French secret-service agents in New Zealand sank the Greenpeace ship, Rainbow Warrior, there was no surge of horror in French public opinion -- even though Frenchmen had sunk a ship and killed a man in the harbor of a friendly country. Imagine the reaction in America if CIA agents blew up a ship and killed someone in Naples or Vancouver!

By the same token, U.S. office holders are vastly more susceptible to the tempests of popular sentiment. One American held hostage by terrorists really does distress the American people and their government. Frankly, the same cannot be said for Europeans. The archbishop of Canterbury's special envoy, Terry Waite, is a hostage of Lebanese terrorists and there has been no press, public or parliamentary outcry in Britain. It is assumed that the British government is working secretly for his release, and that's that.

History helps explain the differences in outlook. Most European countries have been invaded and occupied during the last 50 years. (Eastern Europe, for that matter, still is.) Since 1812, the United States has never been invaded or occupied, and so Americans cannot readily imagine the experience. In Europe, there is a consensus that secrecy is essential, that American levels of publicity about government decisions would result in more intense debate and disagreement than can be afforded, and would risk foreign competitors securing commercial and/or political advantages. America has never had the need to create a very powerful, unified central government to organize scarce resources against military, political, commercial, and cultural invasions.

Still, the fact is that America's Founding Fathers -- even as they built into the American system the checks and balances that guaranteed rivalry and openness -- recognized the need for secrecy. They themselves used it effectively. The Constitutional Convention ruled that secrecy should prevail throughout its deliberations. Imagine what might have happened if the debate on states' rights had been conducted in public: Voters in Rhode Island, pressure groups in New York, commercial interests in Boston, landowners in the Carolinas, all would have mounted strong protests about one element or another. Delegates might have been recalled, the Constitution might never have been born.

Secrecy, in other words, lay at the heart of the democratic freedoms that Congress, the press and every American now enjoy. There is nothing un-American about secrecy, despite the conflict with the very American urge for openness and self-examination.

During times of war, of course, the need for secrecy is virtually unquestioned. But there are many peacetime precedents as well. In the last quarter-century, President Kennedy managed the Bay of Pigs and the Cuban missile crisis from the Oval Office. Congress and the press kept his secrets -- knowing about the events in general but never seeking to make them public until the crisis had past.

Dislike of secrecy is woven into America's national questioning of presidential authority. Intertwined is the still unresolved constitutional question of who controls foreign policy. Ronald Reagan had effectively reasserted presidential authority and gained with it some greater freedom of action in foreign affairs.

But Congress could neither bring itself to support Reagan's Central American policy enthusiastically nor to oppose it forthrightly. The White House felt both driven and empowered to pursue the president's policies through its own channels, outside the established bureaucracies, including the CIA. Now with the revelation of the incoherency of Reagan's secret policies -- the dealing with terrorists even as he publicly deplored them -- we are witnessing another swing of the pendulum.

Because Congress for so long was prepared to leave secrecy to the executive branch, congressmen today have no substantial experience in managing secrets. They have forgotten the intense period of total war, both hot and cold, that lasted from World War II to Vietnam. Their sense of security is reinforced, these days, by Gorbachev's peaceful-sounding Russia. And, just as human beings tend to react defensively to the unknown (or forgotten), an unimaginative Congress has also assumed that secrecy is un-American.

What kind of foreign policy do Americans want? Evidently, not a secret one. But they accept that in the real world some degree of secrecy is necessary for national security and negotiating purposes. Today, therefore, what is needed is a national determination to protect necessary secrets; to implement policies in the national interest that must be secret to be effective.

John Ranelagh is the author of "The Agency: The Rise and Decline of the CIA."