PARIS. — Paris.--ANEW BIOGRAPHY provides a troubling look at a los America, that of Henry Stimson, twice U.S. secretary of war, once secretary of state, governor general of the Philippines, an austere New York lawyer who became the most important American statesman of his time. The book is called ''The Colonel,'' and is by the London journalist and editor Godfrey Hodgson (Alfred A. Knopf).
Henry L. Stimson, 1867-1950, was a public servant of much the same privileged background as George Bush and a number of Mr. Bush's colleagues in the current administration. The difference between him and them, and then and now, is that it is unimaginable that he would have conducted himself as Mr. Bush did in his presidential campaign two years ago, and continues to do in the current congressional campaign, saying mendacious things and making preposter- ous promises in servile attendance upon public-opinion polls.
Not that Henry Stimson was a paragon. He possessed character rather than a particular wisdom. He did not see deeply into his times, nor notably foresee the evolution of the events in which he played a part. He contributed greatly to the unfortunate legalist bias of American foreign policy, evident today in the proposal that the United States put Saddam Hussein on trial.
He had the prejudices of his generation and his class. He considered the non-white races generally backward, and the duty of the white man to give them guidance and tutelage. However he also held that ''we cannot discriminate among our own citizens on the ground of racial origin.''
He negotiated an end to American military occupation of Nicaragua in 1927, but perpetuated indirect U.S. control through a U.S.- trained militia -- an instrument of policy employed in Central America and elsewhere ever since. He was a progressive governor general of the Philippines, but considered the Filipinos incapable of responsible self-government.
He also oversaw the internment in concentration camps of Japanese-Americans at the start of the Second World War, and the development of the atomic bomb and its use without warning to destroy two Japanese cities. He later was an advocate of cooperation with the U.S.S.R. to control atomic energy.
He was formed, politically, by the presidency of Theodore Roosevelt, inaugurator of America's ''enlightened'' imperialism, was William Howard Taft's Secretary of War and Herbert Hoover's Secretary of State. As Franklin Roosevelt's and Harry Truman's Secretary of War he contributed to making the postwar world and what today, a little sadly, we call the American Century. He was a gentleman, at a time when that meant something to his class and in his surroundings. A gentleman does not lie, or debase himself to cultivate public favor. Stimson is the man who in 1929 observed that gentlemen do not read others' mail and shut down the State Department's code-breaking office.
Mr. Hodgson says that Stimson's code ''was an aristocratic one, in which superiority is taken for granted, but must be paid for in the coinage of duty.'' That puts it very well. The point not always grasped is that this superiority ceases to exist if duty is not met.
It may be argued that what has most harmed the United States today is the claim to unearned superiority. The liberal 1960s and the Reagan years both contributed to a belief that Americans could have what they wanted without paying for it in duty, effort, sacrifice, or even taxes. Since this patently is not true, the nation today is awakening to the consequences.
Henry Stimson's character was a matter of personal qualities as well as a difficult childhood, certainly, but it was also the product of a code of behavior and belief generally taught in the United States of his time. It was the code of his class, but it was also the public morality. It is what everyone had told to them in the public schools of the United States. It was held up to the public by preachers and newspaper editors. It was what politicians said they believed, even when they practiced the contrary. It was a code taught as part of American university education, at a time when universities considered it part of their task to instruct ''the whole man'': that is, to impart instruction in morality and ''develop character.''
A writer in Time magazine recently accused this writer of regretting, in a book published last year, the loss of an American ''ruling class.'' But class has nothing to do with it. The loss is of a ruling ethic, and it is a serious loss. Henry Stimson embodied the public ethic of a privileged class, certainly, but it was not an ethic peculiar to his class nor one which served the selfish interests of his class. It was an ethic of public responsibility that Stimson would have considered incumbent upon every American citizen. He was one of a group of public men who from the time of the first Roosevelt to the 1950s largely shaped the modern American world role. This group was not drawn from a particular social class.
It included people of poor working-class origins, such as Dwight Eisenhower, of Kansas, and the Irish widow's son, John McCloy, and from the Midwestern farming middle class, like George Kennan of Milwaukee, as well as from Stimson's own lawyer-banker background of Eastern privilege. Their essential quality was that they knew who they were, and believed that they knew what the United States stood for and what it should represent in the world. They did what they thought right and relied on the public to understand and to follow.
The essential difference today is that Americans are not really confident in what they are, nor in what the nation's values are, nor are they even sure that it is possible, or democratic, to talk about values. Their leaders do not lead. This change goes to the heart of the nation's ability to act, and indeed, to survive.