A ''great debate'' is going on right now in Washington and throughout the community of people concerned about American foreign policy. On the surface it is being waged over whether President Reagan should try to negotiate a new arms control agreement with the Soviets. But the nub of the affair is deeper. What is the basis of American policy toward the Soviet Union to be during the next four years?
Does Washington believe that ''coexistence'' with the Soviet Union is possible on terms the American people can and would be willing to accept? Or must we assume that the Soviet Union nourishes an implacable hostility toward the United States and its political and economic systems so intense that the idea of ''coexistence'' is a propaganda fraud which lulls Americans into a false sense of security.
To understand the intensity that is surfacing now in newspapers, magazines, and television programs, it is important to realize that there are a number of influential people on the Republican right (with some Democrats in support) who think the goal of American policy should be the overthrow of the existing regime in Moscow and that everything we do or say about the Soviet Union should be geared to the attempt to bring down that regime.
I do not personally know of anyone holding these views who goes as far as saying that the US should go to war with the Soviets. The recognition of the mutual destructiveness of nuclear weapons has more or less ruled out public advocacy of war.
But there are plenty of people who came to Washington four years ago believing that the regime in Moscow could be overthrown by political and economic measures and who are holding out now against the President's apparent decision to walk down the ''negotiating track'' with Moscow.
Their intellectual leader inside the administration is Richard Perle at the Department of Defense. Their prime spokesmen in the press are columnists George F. Will, who writes for the Washington Post, and William Safire, who writes for the New York Times.
If you read the latest works by these two preachers of an American ''hard line,'' you will find Mr. Safire lamenting what he calls the new ''peace offensive,'' on grounds that it will build public expectation of a breakthrough toward peace, and saying that this in turn will put pressure on the President which might push him toward unwise concessions to the Soviets.
Turn to Mr. Will and you will find him deeply upset because Jeane Kirkpatrick , a member of the right-wing group in foreign policy, is not being brought to Washington either as secretary of state or as national-security adviser at the White House. He now urges that she keep her post at the United Nations in order to have a ''place at the table'' in policymaking.
Mrs. Kirkpatrick is needed, he writes, because President Reagan ''is inclined to indiscriminate optimism,'' which in foreign policy ''produces a reluctance, even an inability, to understand that problems will not be dissolved by better communication, that the cold war is not just a misunderstanding, that all human beings are not 'basically alike.' ''
In other words, the hard-liners think President Reagan has gone soft on the Russians and is taking a dangerous road away from the old original Reagan line, which assumed that Moscow was the source of all evil in the world and should be opposed and resisted at every turn. They are unhappy about seeing him talk and act in terms which assume that ''coexistence'' is conceivable between the US and the USSR.
Much is at stake here. The political hard-liners in Washington are largely funded by the corporations that build the weapons which are justified by the doctrine of Soviet implacable hostility. To negotiate with the Soviets is to assume that there are things worth negotiating about.
Mr. Reagan is taking a bold step in committing himself to the ''negotiating track.'' No one can foresee how far he will try to go down that track. But we can know that at every step Mr. Will and Mr. Safire will be thinking up reasons he should stop and turn back.