The mandate at home is clear enough: more of the same economic uplift (without tax increases). But what was the mandate abroad? Muffled, to begin with; exit polling suggests that foreign policy concerns took a back seat to take-home pay and the magic of the president's personality.

And also muddled. If past performance and campaign promises were taken into account in equal measure, the vote for president gives Ronald Reagan all the running room in the world. But the vote for Congress takes some of it back by strengthening the Democrats a bit in the Senate and leaving largely intact a Democratic restraining hand in the House.

The election returns and the exit polls confirm that when it comes to national security, Americans have driven themselves -- or been driven -- into a crazy, mixed-up frame of mind.

Voters told the exit pollsters last Tuesday that they preferred Reagan for leadership, but favored Mondale's chances of keeping us out of war. They voted nationwide for a president who has achieved no arms control agreements but who pledged that he would make arms control a high priority in his second term. They went wild for a president who spent three years lambasting the Soviets and the last few months demonstrating his intense interest in finally meeting his Soviet counterpart.

They commended or countenanced a foreign policy that: put U.S. prestige and influence heavily at risk, losing a lot of both, along with the lives of nearly 300 U.S. servicemen, in Lebanon; scored a smashing, crowd-pleasing victory in little Grenada; got nowhere with a Middle East peace initiative; won its way on the deployment of U.S. nuclear forces in Europe; assembled a splashy $8 billion economic aid program for Central America; embarked on a not-so-secret war against the Nicaraguan Sandinista government.

If the Reagan majority thus gives the impression of being at odds with itself, a recent study conducted by an outfit called the Public Agenda Foundation can explain everything: American public opinion is profoundly at war with itself. The foundation is a nonpartisan group whose chairman is former secretary of state Cyrus Vance; its president is the respected public opinion expert and pollster, Daniel Yankelovich.

In presidential years, the foundation prepares briefing books for the candidates. This year's briefing, compiled in collaboration with the Center for Foreign Policy Development at Brown University, concentrated on nuclear arms policy. As the study observes, the picture presented of the "nuances of American attitudes" is one of "enormous complexity."

By majorities of varying degree, Americans believe the Soviet Union is "an evil empire" and that it will "lie, cheat and steal -- do anything to further the cause of communism." Two- thirds of the public thinks we should insist on on-site inspection to verify any arms control agreement. But when the question is put slightly differently, 56 percent of the public is ready to sign an arms control agreement with the Soviets, even if foolproof verification can't be ensured.

A narrow plurality is found in favor of using U.S. military force to prevent communist revolutions in other countries. Almost two-thirds agree that the only language the Soviets understand is force, that we have to prove to them they can't push us around; some 78 percent think that's what the president proved in Grenada.

But even larger majorities believe our experience with communist China proves "our mortal enemies can turn into countries we can get along with"; that we should "live and let live because there is room for our system and the communist system to coexist in the world"; that if we weaken the Soviets at every opportunity, they may become, like cornered rats, more dangerous.

Underlying these apparent contradictions lies a tormenting concern over nuclear war that has increased "massively" over the past 20 years, the foundation reports. Out of this concern has developed a clear American consensus: "Upwards of 75 percent of the American people, in every demographic group, now agree that to engage or risk nuclear war would be to risk nuclear suicide and that the danger is not remote or distant, but real and urgent."

It is this that makes it possible for an overwhelming majority to believe 1)that the Soviets are dangerous adversaries who are "constantly testing us, probing for weakness and quick to take advantage whenever they find any," but 2)that "picking a fight in the nuclear age is too dangerous a policy and it is in our best interest to negotiate, to think of peaceful solutions rather than aggressive ones."

Now that is not a precise prescription for managing the U.S. role in the world. But it does reinforce the election-night analysis of Henry Kissinger. He isn't sure the Soviet leadership may not be too divided by their "succession crisis" to be able to negotiate -- even if they decided to do so. But it's his hunch that Ronald Reagan has decided.

If that's so, the Public Agenda Foundation's findings support Kissinger's conclusion that "with this overwhelming mandate, (the president) is in a very good position." That may be the main message, however muffled, on foreign policy in Reagan's towering victory.