America's establishment': a close-up look; The American Establishment, by Leonard Silk and Mark Silk. New York: Basic Books. $13.95

Out of every society there inevitably emerges a relatively small, fiercely exclusory band of individuals, often nonofficial, who reflect that society's power blocs and who seek to envelop and guide the ultimate decisionmaker: king, premier, dictator, or president.

In Britain, and now in the United States, it has become fashionable in recent years to depict as the "Establishment" that shadowy congeries of bankers, industrialists, foundation executives, politico-academics, and mass-media heavies who seem to ebb around successive administrations with the effortless tenacity of seaweed on a Maine beach.

The term Establishment, first used in 1953 by the British historian A. J. P. Taylor, was transposed to the New World, in 1961, by the late, brilliant Richard Rovere of The New Yorker in his musings on the lemming-rush out of Harvard, Wall Street, and such power bastions into the Camelot administration of John F. Kennedy. Ever since, it has been on everyone's lips -- pejoratively -- according to Leonard and Mark Silk, authors of the perceptive and stimulating "The American Establishment."

The Silks are well placed to analyze this potent, if spectral, entity, whose members often deny, or plead ignorance of, its very existence. Leonard Silk is the noted financial columnist of the New York Times; his son, Mark, a teaching fellow in history at Harvard. Understandably, they have selected their own respective organizations as two of the chief pillars in this power pantheon.

The others include the august Council on Foreign Relations, the Ford Foundation, the Brookings Institution, and the Committee on Economic Development -- all recruiting centers for successive administrations and holding areas when administrations change.

The Silks' conclusions? In short, the "Establishment" does, indeed exist and seeks -- with mixed success -- to serve the public weal. It is, they say, a third force between business and politics. "Where the aim of business is profits and the aim of politics is power," the authors contend, "the aim of the Establishment is disinterestedness and public morality." Some, recalling the Vietnam and the post-Watergate revelations of corporate chicanery, may lift a quizzical eyebrow.

Nonetheless the authors, pere et fils, make a provocative, often witty, case for this influential grouping. Its ethos, they maintain, is to "Be Serviceable, " and they trace its roots partly to the great Eliot of Harvard with his legacy of Unitarian toleration and his advocacy of unfettered academic freedom.

A second key influence was Walter Lippmann, whose epochal "A Preface to Morals," in 1929, proposed to a disillusioned America "disinterestedness" as a national creed. Gradually, as the Silks ably show, the blacktie morality of such high-minded founders of the Council on Foreign Relations as Elihu Root, John W. Davis, and Henry L. Stimson, the pledge of Adolph Ochs to publish the New York Times "without fear or favor," the philanthropy of the Carnegies, Rockefellers, and Fords, began imbuing the Establishment with a sense of public service, uniquely American not only in its "voluntarism" but in its domination by men of affairs and not, as in Europe, by governments.

Predictably, the Establishment has had its ups and downs. Hostile to FDR's New Deal, it remained on the sidelines until Pearl Harbor, when there was a patriotic rush to man the barricades. From the Establishment came Roosevelt's and Truman's greatest proconsuls: Stimson, Patterson, McCloy, Lovett, Acheson, David Bruce, and Harriman.

Vietnam, however, marked its nadir: Too many of its "best and brightest" were perceived as hawks -- the Bundys, the Rostows, Cabot Lodge, McNamara, Rusk. The Establishment, wiser but scarred is girding for a comeback even as many Americans continue to assail the "elite, do-gooders, liberals."

Dismissing such rhetoric, the authors do assert one "extremely serious" charge can be leveled at the Establishment: it occasionally pursues its private interests under the mask of disinterestedness. The Silks cite the Rockefeller-Kissinger-McCloy maneuver to bring the ailing Shah of Iran to the US as a case in point.