Why do people attack the United States and its institutions? Because, the common-sense answer goes, they are enemies animated by hostile interests.

But the assaults can be explained in a different way by a theory -- the theory that aggression results from frustration generated by legitimate grievances. That theory is now so persuasively held in this country, it is applied so automatically -- and so often inaptly -- as to constitute a national sickness: the American disease.

The view that frustration begets aggression, to be sure, is not native to our shores. It was developed by Freud in Vienna at the turn of the century. It has enjoyed worldwide esteem as a framework for the treatment of neurotic individuals. But as a tool for diagnosing and correcting social and political problems, the Freudian thesis commands less than universal acceptance.

The Chinese, for example, believe antisocial behavior results from having bad ideas. So groups and individuals who make trouble are sent to camps where, while laboring, they undergo extensive self-criticism and self-correction.

The Europeans, including many Russians, regard antisocial behavior as juvenile and "uncivilized." They visit on aggressive actions the stigma of class discrimination -- which is one reason that in Britain both the snobbism and the social cohesion are so impressive.

The United States, however, started with a high quotient of guilt. The Puritan ethic, so formidable in shaping the views of both the early settlers and many immigrant groups, held that effective action was moral action. When action turned out to be ineffective, it followed that it was not moral. That long-standing disposition to feel guilty about failure created an atmosphere of sympathetic harmony for the Freudian notion that aggression was not so much the work of hostile enemies as a reaction of decent people to bad treatment.

The grafting of the theory to American social problems was achieved in a systematic way as early as 1939. In that year -- as Pat Moynihan, the brilliant social critic turned senator who has been my guide in this matter, has pointed out -- Yale sociologist John Dollard published a book entitled "Frustration and Aggression." Dollard used the theory to explain why poor whites discriminated against blacks in the small towns of the South. He felt the theory was relevant to "many diverse phenomena" such as lynching, criminality, suicides and war. Still, he asserted the case modestly.

Since then, the vast store of unease felt by the chief beneficiaries of this country's postwar prosperity has been added to the residue of Puritan guilt. At the great universities and law firms, in the leading newspapers and networks, in the more enlightened corporations and in the higher reaches of government, the Freudian theory had become, by reflex action, the accepted explanation for each and every disturbance.

Thus the black riots of the 1960s were put down to the frustration engendered first by discrimination and then by ghetto life. The recommended therapy of enlightened society was "maximum feasible participation" by blacks in "community action." The student protests that followed were ascribed to "alienation" from cold, bureaucratic educational systems. The remedy was supposed to be student participation in university "governance" -- a new word founded especially for the occasion.

When the Vietnam War became an issue and, indeed, until very recently, the fashionable view was to scorn the notion that the North Vietnamese might be aggressive expansionists. The war they waged against the Saigon regime and its American backers was said to be merely the inevitable result of American imperialism as practiced by "the national security apparatus." In some literary circles it was even suggested that the United States would have done far better if it knew more about Vietnamese traditions of ancestor worship.

Now there has come the test of strength with Ayatollah Khomeini. The seizure of the embassy in Tehran was a blatant act of aggression that took place againt a background of organized hostility to this country. But the administration at first responded as though the problem were to identify Iran's grievance and make accommodation. Even now some journalists make it seem that the villain of the piece is Ayatollah Kissinger.

I do not mean to say that the United States is perfect. This country did treat blacks badly and did organize mega-universities and did support corrupt and tyrannical regimes abroad. Nor would I deny merit to the aggression-frustration model of behavior. This country has been particularly good at fostering fruitful relations with the European allies because it tends to anticipate resentments and smooth them out before they become king-sized.

But the model is not universal. There are occasions when the United States has to deal with persons and groups that can only be fairly described as enemies; and unless that is understood -- and soon -- the American disease could turn out to be terminal.