The rhetorical dust thrown up by this fall's presidential campaign may hide the fact, but Jimmy Carter and Ronald Reagan actually do hold profoundly different views of this country's proper role in the world.

They are classic American views, reflecting the ambivalence Americans have always brought to their dealings with the outside world. Buy they diverge on many points and are contradictory on others.

Reagan is a believer in simple truths -- most basically that, to achieve the protection of its international interests, the United States must pursue them forcefully and without equivocation. For years, Reagan has advocated an "or else" approach to situations in which other countries try to frustrate American desires or interests.

Jimmy Carter draws on another strain of the national character. In his vision of the world, America is the first of all a moral beacon, a nation whose power comes from the force of its example as much as the power of its Army or its economic strength. Carter has had great difficulty converting that vision into consistent, effective policies, but he has stuck by it.

For political reasons, both men have tried to avoid differentiating their positions too explicitly this fall. Both now tend to advertise themselves as peace-through-strength men. Meanwhile, Carter tries to paint Reagan as too preoccupied with strength and its use, and Reagan depicts Carter as bedazzled by naive visions of how to achieve peace.

Public opinion polls available to both candidates show that Americans tend to be fervent if inconsistent supporters of both a tough line and the ardent pursuit of peace, a potential contradiction that probably explains the two candidates' desires to becloud the national security issues this fall. But if one looks beyond the campaign rhetoric to the formation of Carter's and Reagan's basic reflexes on foreign policy issues, the differences between them become much clearer.

Stated opinions on issues, of course, do not provide reliable guideposts to future policies. A president must muster the skills of political leadership to convert opinions into effective policy, and Carter's abilities on that score are one of the issues of the 1980 campaign. Reagan's potential as a statesman remains uncertain.

John B. Anderson, the independent candidate whose campaign is considered at best a long shot, campaigns on national security positions much closer to Carter's than Reagan's, though he criticizes both of them for encouraging a "mindless" escalation of the arms race. As candidate and congressman, Anderson has opposed the MX missile and the B1 bomber and supported the SALT treaties.

Reagan's basic positions have been remarkably clear and consistent for many years. Here is a classic formulation of the former governor's blunt approach, this one on the issue of the American hostages in Iran:

"What you say in a situation of that kind -- and you don't say it in the newspapers -- you say it directly to them: 'We want our people back and we want them back today or the results are going to be very unpleasant.'"

Reagan said that last month. Four years ago, recommending a course of action to rescue the American sailors taken prisoner by North Korea on the USS Pueblo, Reagan said this:

"The only defensible action, the only moral action, was to move out 7th Fleet into position outside the harbor and then say to the North Koreans: 'Send our ship and our men safely out of that harbor within six hours or we're coming in to get them, and we'll use planes, guns, torpedoes, whatever it takes.'"

As these examples suggest, Reagan's basic instincts in many issues haven't changed over the years. His consistency has gotten him into hot water this fall, first when he stuck by his longstanding pro-Taiwan position, sabotaging his own running mate's trip to China in August, and then when he pronounced the Vietnam war a "noble cause."

That "noble cause" was no slip of the tongue. Reagan wrote it into the text of a speech himself. In 1976 he fervently defended American participation in Vietnam. The war, was an attempt by the United States "to counter the master plan of the communists for world conquest, and it's a lot easier and a lot safer to counter it 8,000 miles away than to wait until they land in Long Beach."

"There is a communist plan for world conquest," Reagan said four years ago, and . . . it's final step is to conquer the United States." If the American people were told the truth about that master plan, they would be willing to take steps to counter it, he said.

Reagan has always referred to the communist threat in stark terms. In his famous 1964 television speech for Barry Goldwater, Reagan delivered one of his classic perorations:

"We are at war with the most dangerous enemy that has ever faced mankind in his long climb from the swamp to the stars, and it has been said if we lose that war, and in so doing lose this way of freedom of ours, history will record with the greatest astonishment that those who had the most to lose did the least to prevent its happening."

For years, Reagan told audiences and interviewers that the American people had to be ready to make sacrifices to stand up to the communists and "beat them at their own game." He liked to quote Churchill's warning to the British after the Nazis seized Czechoslovakia: "This is only the first sip, the first foretaste of the bitter cup which will be proferred to us year by year, unless a supreme recovery of moral health and martial vigor we rise again and take our stand for freedom as in the olden time."

After quoting that passage in 1976, Reagan added: "[Churchill's] words are now our destiny."

Words like these have never come from the lips of Jimmy Carter. In the early Cold War years when Reagan first formulated personal views of world affairs, Carter was absorbed in his naval career. When he later got into Georgia politics he had no need to state foreign policy recommendations. When he did say something it came out sounding thoroughly conventional. He supported the Vietnam war, for example.

Carter began to formulate a more original (and politically more marketable) world view for his own presidential campaign. During 1976 Carter began to articulate an optimistic and moralistic prescription for reshaping American foreign policy. Carter the campaigner laid out the basic lines of policy that Carter the president pursued for the first phase of his administration, and which clearly distinguish Carter's view of the world from Reagan's.

The 1976 Carter said America had lost its way in the world. "It must be the responsiblity of the president to restore the moral authority of this country in its conduct of world affairs," he declared. "For too long, our foreign policy has consisted almost entirely of maneuver and manipulation, based on the assumption that the world is a jungle of competing national antagonisms, where military supremacy and economic muscle are the only things that work and where rival powers are balanced against each other to keep the peace."

"Exclusive reliance on this strategy is not in keeping with the character of the American people, or with the world as it is today," Carter said in 1976. He promised a new approach, and a foreign policy "as open and honest and decent and compassionate as the American people themselves are.

Carter has been talking about the complexity of the world's problems and the plaucity of easy answers to its problems since he first began speaking seriously about foreign policy. At the same time, he has always spoken confidently of America's ability to prevail in this complex world.

"We are confident that democracy's example will be compelling," Carter said in his May 1977 speech at Notre Dame, probably the best single statement of the president's world view. "We are confident that democratic methods are the most effective . . . We are confident of our own strength . . . ."

Repeatedly Carter has trumpeted America's moral strength. The world "will always be complex and confused," he said at Notre Dame, adding, "I understand fully the limits of moral suasion . . . . But I also believe that it is a mistake to undervalue the power of words and of the ideas that words embody . . . . The great democracies are not free because we are strong and prosperous. I believe we are strong and influential and prosperous because we are free."

Where Reagan has always seen the world primarily in terms of the Soviet-American contest, the early Carter insisted that this was a mistake.

Of course, Carter's early optimism that America could move beyond the confining competition with the Soviet Union has been altered by events.The Soviet invasion of Afghanistan pushed Carter in a new direction. Now he advocates substantially increased defense spending, sanctions against the Soviet Union and a harder line generally.

"The action of the Soviets [invading Afghanistan] has made a more dramatic change in my own opinion of what the Soviets' ultimate goals are than anything they've done in the previous time I've been in office," Carter told ABC News last Dec. 31. It is a quotation for which Carter has been repeatedly ridiculed by Republicans, and the president even denied saying it in another interview with Meg Greenfield of The Washington Post.

Whatever the changes Afghanistan has caused in Carter's thinking, though, he and Reagan still disagree significantly on the central issues of Soviet-American relations -- the military balance and SALT. In both cases, the two candidates seem to be following their traditional instincts.

Reagan says he would withdraw the SALT treaty from the Senate and tell the Soviets that they will have to negotiate a new one more favorable to the United States and/or more clearly directed at actual arms reductions, rather than the controlled expansion of nuclear arsenals that SALT II would permit. This invitation to a renewed arms race would be a radical departure from the policies of the Nixon, Ford and Carter administrations. It would cause concern among America's NATO allies, who have consistently given strong support to SALT II.

During the campaign Reagan has said that there hasn't been a real arms race in years, because only the Soviets have been racing. He appears anxious to correct the insufficiencies in American strategic posture that he perceives, though he has declined to spell out the weapons programs he believes necessary -- or their costs.

Reagan has campaigned in favor of restoring American superiority over the Soviets, a concept he refers to as "restoring a margin of safety" for the United States.

On all these points, Carter has stuck by his pre-Afghanistan positions. He wants SALT II ratified after the election; he rejects the concept of strategic superiority as unrealistic; he defends current and planned U.S. force levels as adequate.

The two candidates have also laid out starkly different positions on the correct American attitude toward political change in the Third World, an issue that has barely been mentioned during the campaigning, but which is bound to recur in real life during the next four years.

Carter stated a position that he has stuck by in his Notre Dame speech in 1977: "Being confident of our own future, we are now free of that inordinate fear of communism which once led us to embrace any dictator who joined us in that fear." Republicans have lambasted the line, interpreting it to mean that Carter decided to stop fearing communism. But it contained the justification of something else -- a policy of accepting, even welcoming changes in some countries even if that meant working with communists or Marxists against leaders who proclaimed their staunch anticommunism.

Carter followed that policy in Rhodesia and Nicaragua, for example, and Reagan ridiculed his approach to both. The Republican candidate strongly supported the formula for limited majority rule in Rhodesia negotiated by Ian Smith and some black leaders, and he defended the Somoza government in Nicaragua as less than ideal but preferable to the alternative -- "a Castroite, Marxist state in Central America."