The Fourth of July is the right day to ask the big question of American foreign policy: How independent is the United States today? To what extent can we define and serve our own interests in the world? Is it still possible for the United States to act, within decent limits, as a proud, strong, sovereign nation essentially in control of its own destiny? Or is that expectation the result of a lingering but no longer supportable myth that we indulge today at our peril?

Jimmy Carter brought one answer to Washington; Cyrus Vance departed still holding it. It comes down to a belief that the world is a newly complex place in which increasing interdependence has diminished the utility of sovereign power, including military power, and forced the United States to rely on a policy of scaling down old interests and adjusting to new "realities." Robert W. Tucker of Johns Hopkins University, on whose analysis I lean here, calls this the "modernist" view of power.

"Let us keep in mind the world from which we start: a would undergoing rapid change," Vance said at Harvard on June 5. "The international diffusion of power" is the new fact that will not go away. But: "If we are prepared to accept the implications of a world of diffues power, and work with others where we cannot succeed alone, there need be no insurmountable barriers to our progress."

The second answer is the "traditionalist" view of power, which is implicit in Ronald Reagan's approach to foreign power and which has been made explicit by many critics of Carter's policies, including, notably and recently, Norman Podhoretz, author of "The Present Danger."

In this view, interdependence has not made the system of sovereign states obsolete, and national power, including military power, is still the basic commodity in international affairs. This power, far from being devalued by interdependence, is the revalued antidote to the drags of interdependence. It follows that the American problem is to amass and assert power. As Podhoretz puts it in his new essay, "Do we have the will to reverse the decline of American power?"

So how will you have it on Independence Day? Will you go with the flow, with the (at least) old Carter and with Vance? Or will you stand up and prepare to fight, with Reagan, Tucker and Podhoretz? If you go the first way, then, say its critics, you will be run over by the implacably hostile forces at loose in the world. If you take the second way, then, say its critics, you will be undone by your own "dangerous nostalgia."

It is a vigorous debate but it has a quality of caricature ot it. The world has changed, and the United States does not enjoy the relative dominance and freedom of action it unquestionably enjoyed in the immediate postwar years. But the world has not changed so much that the United States no longer has the wherewithal or leeway to put any of its still great power to effective use. What is so difficult to understand about all that?

Vance -- forget Carter, for now -- remains in thrall to a Vietnam hangover that makes it difficult for him to imagine how the United States could use force wisely. He exaggerates a condition of "diffused power" in which the tough questions are simply finessed. Vance can scarcely mention the word aggression in respect to Afghanistan. The challenge of the Kremlin is to "manage a competition." It is naive to believe that the Russians will play by our rules any more than we will accept theirs, he says. What does Vance mean by the words I have italicized? Our "rules" would regulate competition. What comparable Soviet rules exist?

But if Vance ends up spoiling the case for balance with naivete and flabby logic, then Podhoretz overwhelms the case for alertness with hysteria and hyperbole. True, the liberals have given their critics a fat target. But Podhoretz, with his supposedly steely intellectual bead, loses the focus. The specter he sees is "the Finlandization of America, the political and economic subordination of the United States to superior Soviet power." What might muddy that image is simply not visible on his screen.

So how independent is the United States on Independence Day? Surely there is a level-headed open-eyed way to approach the question that is at once consistent with our traditions and responsive to our needs. We are in the sort of genuinely novel and difficult circumstances that give rise to widely divergent formulations for relief. The dogma of neither left nor right will do.