If half the art of political leadership is the ability to persuade, as we are so often told, then Ronald Reagan is halfway home. His speech to the Congress and the American people last Wednesday night on problems in Central America was his finest rhetorical performance as president.

For Reagan to deliver a speech well hardly merits note. But his address this time went beyond his customary display of polished skills--the pleasing manner, the soft-spoken sincerity, the nice-guy tone--that by now are so familiar. Effective though he almost always is, Reagan often leaves one feeling that it is more the performance than the content that counts.

This time, he conveyed something more than a sense of style. He spoke with passion. There was no doubt about his conviction. He was firm but not bellicose. He came over as a forceful leader doing what strong presidents do best: taking his case to the people and their representatives, and laying it out in unmistakable terms.

The case, as he presented it, certainly deserves the grand forum he chose. For here was the president of the United States warning fellow citizens about what he believes to be a great peril directly facing them, one raising the gravest national-security implications. His message bristled with what he perceives to be these ominous stakes affecting, as he put it, "our lifeline to the outside world."

Through his words he conjured up an image of an entire region, "from the Panama Canal to Mexico on our southern border," becoming destabilized by U.S. enemies. Unless the country follows his proposed course and acts, the people of Central America "will be delivered to totalitarianism, and we ourselves will be left vulnerable to new dangers," he said.

His message could not be more clear. Either "save" Central America or see the tide of Marxist-Leninism sweep over our borders and engulf us.

Lest there be any misunderstanding about the stakes, he linked his appeal to that of President Truman's historic drawing of the line against Soviet advances in 1947 that became the operative political stance for the United States around the world throughout the Cold War era. But in his view this problem lies far closer to home. In effect, he was saying, act now or they'll be in the foothills of Maryland.

Yet in the end, despite his superb rhetorical gifts, the president's address left this observer with the weary and disquieting feeling that we've suffered through all this before. And I don't mean Vietnam, either.

The problem lies not with the president's rhetoric about Central America. It lies with his history.

The most disturbing lines in Reagan's speech were also the ones that embrace his most encompassing historical analogy and rationale for action.

"If the United States cannot respond to a threat near our own borders, why should Europeans or Asians believe we are seriously concerned over threats to them? If the Soviets can assume that nothing short of an actual attack on the United States will provoke an American response, which ally, which friend will trust us then?" he asked.

It is the "America as a paper tiger" line that we heard so often over the last generation. It is President Nixon's line about "America as helpless, pitiful giant." It is President Johnson's "what can we do in Vietnam if we can't clean up the Dominican Republic?" line in the spring of 1965 as he dispatched Marines into Santo Domingo in the Caribbean, and then, weeks later, dramatically raised the military ante in Southeast Asia by putting combat troops ashore in Vietnam.

In fact, the history of the postwar period teaches a different lesson about U.S. willingness to employ its power in the world.

At virtually no point since the Truman Doctrine laid down the challenge to Soviet expansionism has the United States failed to engage its economic and military power. Over the decades since, we have expended our blood and treasure in extraordinary measure. We have toppled Marxist regimes (Guatemala) and presumed Marxist figureheads (Iran). We have experienced great successes (Greece and Turkey, the Berlin airlift, the Marshall Plan, the Cuban missile crisis), notable stalemates (Korea, hostages in Iran) and failures (the Bay of Pigs, Vietnam). Even in the closest example of U.S. impotence, Iran, we finally opted for a military mission, albeit a doomed one.

The record of U.S. willingness to act forcefully thus is crystal clear to allies and foes alike.

You can argue that our moves have not always been wise or well-executed but not that we have lacked the will to act.

Perhaps nowhere is that debate about the wisdom of our actions, about choosing between starkly differing courses, more vividly portrayed than in relations with our neighbors to the south. That is only one reason why the premise underlying the president's address deserves the sharpest examination and debate.

Listening to Reagan leaves the impression that our choice is a simple either/or one. Just back the right guy or group and the bad guy or group will lose. Give them the tools, and that means military ones, and with a little help from us they will do the job. Democracy, being good, will triumph over socialism, being bad.

That totally misreads the history of the region and our role in it. Again and again, we have seen the dreary cycle repeat itself: A brutal dictatorship of the right is replaced by an equally brutal one of the left. A Batista is deposed in Cuba, and a Castro takes his place; a Trujillo is toppled in the Dominican Republic, and a leftist regime assumes power; a Somoza is overthrown in Nicaragua, and another despot seizes control.

Nicaragua goes from being a staging area for U.S.-backed covert operations--springboard for the Bay of Pigs invasion--to a fountainhead for communist subversion in the hemisphere.

There is no simple either/or solution in the impoverished societies of Central America, no single choice between military or economic assistance, certainly no short-term answer. Just the opposite is true. The region needs our assistance and understanding, our economic and military aid, our long-term efforts to work in concert with all the nations there and, yes, our determination to oppose totalitarianism and subversion wherever and from whatever side it arises.

From the president, one gets the idea that our policy is based on countering force by force, on opposing one rebel group, theirs, by another, ours. In the old philosophical argument about whether revolutions are won through the barrel of a gun or the clash of ideas, it would appear he picks the gun.

The problem involves something more than a debate about America's willingness to act. The debate is about the wrong terms. And in Central America especially, the tragedy is that we discover the region only in times of crisis and then always seem to respond in a military context.