Three days after the Iraqi invasion of Kuwait, former Secretary of Defense James Schlesinger rushed into print to declare that "there is no effective policy option available to respond to the seizure of Kuwait." An oil embargo? That would be so ruinous to us that Saddam "could be assured that any threat not to buy his oil would be an idle one."

The United States, wrote Schlesinger, is "now attempting to persuade all nations not to buy Iraqi oil." But other nations will cheat and thank goodness for it: "Other nations will be buying Iraqi crude at knockdown prices, but that is better than our being successful in our attempt (at embargo), for that would be devastating."Four months later, Senate Armed Services Committee Chairman Sam Nunn kicks off the national debate on war and peace in the gulf by calling as his lead witness the same James R. Schlesinger.

His message? That the embargo on Iraq is such a smashing success ("the most successful ever achieved aside from time of war") that it must not be interfered with by any precipitous military action.

Schlesinger's, . . . er, flexibility on this issue did not seem to bother the senators. In four hours of hearings, not one senator was so indelicate as to ask the Schlesinger of November about the Schlesinger of August. Why? Because for most members of the committee, today's Schlesinger is a most useful witness: a reputed hard-liner who makes the case they want to make - the case against war - without their having to make it.

The Democrats' agenda in these hearings is clear: To raise enough doubts about current American policy to give them cover if it fails. But to stop short of openly voting for their preferred policy - indefinite sanctions - because that would make them responsible for its success or failure. Hence the choice of Schlesinger - followed by two former chairmen of the Joint Chiefs of Staff - to present their victory-through-embargo line.

As part of the choreography, Nunn began the hearings in utmost modesty, not with answers but with questions. "What are our vital interests in the Persian Gulf region?" "Will United Nations economic sanctions force Iraq to withdraw from Kuwait?" "How durable is the multinational coalition?" Etc.

Important questions all. But they are not new: Everybody who has been thinking about the gulf has been struggling with them for the past four months. Moreover, the reason that these questions are still around after four months is that they have no definitive answer.

There are simply too many unknowns: the stability of the Saudi regime, the morale of Saddam's troops, the staying power of the American public, the rate of breakdown of Iraqi equipment, the rate of breakdown of the allied coalition. And war itself is a maelstrom of contingencies.

Nunn is not going to get clear answers to his questions. And questions alone are cheap unless, in the end, one is prepared to make a judgment. In an atmosphere of unavoidable uncertainty, the president is going to have to make a decision. So should Congress.

Simply holding hearings is a way for Democrats in Congress to put themselves in a no-lose position. If the president chooses war and it turns out badly, they can say I told you so.

If the president chooses war and wins, who will then remember the questions and the doubts amid the general euphoria? After all, we've just won the Cold War, and all those defeatists who had urged that we sue for peace now act as if nothing had been said. If the McGoverns, the Fondas, the freezeniks of the world have been chastened, I've missed it.

In fact, many are back with free advice on the gulf. The Catholic bishops met earlier this month and once again deplored war and contraception.

The gulf battle lines today are becoming clear and quite partisan. Republicans (most, for now) support the president as he marches toward a winter war. Democrats tend toward sanctions and no-war policy. But most prefer to have others say it for them.

Claiborne Pell, chairman of the Senate Foreign Relations Committee, holds his own set of gulf hearings Dec. 4 with a stacked witness list. Apart from Secretary of State James Baker, eight witnesses have been chosen by the Democrats. Not one has expressed support for the president's war policy.

Zbigniew Brzezinski counsels containment. The National Council of Churches counsels withdrawal. In between are such Democratic doves as Arthur Schlesinger, Robert McNamara and John K. Galbraith. And, of course, the bishops. No anti-war parlay is complete without them.

The choice between containment and war is agonizingly difficult. The outcome for each is highly uncertain. But choosing in contingent circumstances is the essence of policymaking. Questions and stacked hearings will not do.

Congress has to decide. The president should call Congress back into session immediately, present it with a resolution authorizing the use of force and make the gutless wonders choose.