President Carter tonight invited American voters to concentrate on the "stark choice" future directions he and Ronald Reagan are offering -- and, implicitly, to forget what his critics call the equally stark contrast between his promise for America and his performance.

In using the vast audience provided by network coverage of his acceptance speech to concentrate on the contrast between the "security," "justice" and "peace" he envisaged for his own second term and the "despair," "surrender" and "risk" he said would come with Reagans election, the president was defining the issue in the 1980 election in the only way his advisers think he has a chance to win. i

Admittedly trailing Republican Reagan being hampered in his comeback hopes by the presence in the race of independent John B. Anderson, Carter followed advice to get the emphasis off his own record in office and onto the latent fears about Reagan's capacity for leadership.

"If this election is a referendum on whether Americans are satisfied with the way things have been going," one leading Democratic pollster said, "we lose -- and lose bad."

That kind of referendum is exactly what Reagan sought to set up when he told the Republican National Convention in Detroit a month ago that Carter would be held to account for the "unprecedented calamity which has befailen us" --a disintegrating economy, a weakened defense and an energy policy based on the sharing of scarcity."

Predictably, Carter sought tonight to put a better face on current conditions, claiming that military power has been restored, oil imports reduced and 8 million new jobs created.

But rather than risking his shaky prospects on a cosmetic gloss of today's economic and international scene, Carter portrayed himself as a man who has learned that "the true constituency" of a president "is the future,"

In his text, he did not neglect the traditional and influential Democratic constituencies of today -- city dwellers, farmers, union members, blacks, women, the elderly and the Jews. There were specific appeals to all of them.

But he left most of the heavy work of cheerleading the variegated factions in the convention hall to his running mate, Vice President Mondale, who delivered much more of a traditional rally speech than did Carter.

Except for a personal word of praise for his vanquished challenger, Sen. Edward M. Kennedy, and an equally personal appeal to "Ted" for help, Carter overlooked the controversies that divided his party during the nine-month nomination battle and stirred strong emotions during the first three days of this convention.

Not only was he eager to shift the focus from the Democratic infighting of the recent past, he was also anxious to avoid the traditional incumbent's claim that he had fulfilled his own past promises.

With Reagan deriding "trust me" government -- in a cruel turning of Carter's own 1976 catch-phrase -- the president did not recall that four years ago, in the same hall, he had promised, among other things, a balanced budget, a comprehensive national overhaul of the tax system, and had said, "You can depend on it."

Nor did he come close to matching the power and effect of his 1976 speech. Although aides said Carter was not aiming for cheers in the Garden he appeared to strain for applause, forcing his voice and persipiring with the effort. In its debut before a supportive audience, the new campaign strategy seemingly evoked little spontaneous enthusiasm -- and the cheering during the closing ceremony was sporadic until Kennedy finally arrived on the podium to join Carter and Mondale and a horde of other Democratic leaders for the "party harmony" picture the convention manager had struggled for days to arranger.

Even that picture was a disappointment, as an unsmiling Kennedy side-stepped every effort to maneuver him into joining hands with Carter and Mondale in a shared salute to the delegates and a commitment to victory.

During his address, Carter described the 1980 election as "a stark choice between two men, two parties, two sharply different pictures of America and the world. . . . two futures."

The repeated emphasis on the two-way choice was no accident. It was Carter's way of denying the reality or validity of the Anderson option, even as the independent challenger was wooing dissident delegate who walked away from the Democratic National Convention.

But the emphasis on "two futures" was more than that. It was the start of a basic Carter campaign strategy to make voters think hard about what a Reagan presidency would mean for them and the country.

During the nomination contest with Kennedy, when Carter remained in the White House, his surrogates and his aides brilliantly exploited doubts about the challenger's character and policies, and managed to make Kennedy the issue.

The Carter strategists are convinced they can do the same thing with Reagan -- focusing not on his character, but on his competence, his social conscience and his comprehension of worl realities.

In rhetoric that is sure to escalate as the campaign continues, Carter suggested that Reagan lives in "a world of tinsel and make-believe . . . a fantasy world . . . where some politicians shoot first and ask questions later."

Reagan's main economic proposal, an across-the-board tax cut, spells "rebates to the rich, deprivation to the poor and fierce inflation to the rest of us," Carter said. Who would want that kind of future?

Reagan's defense and arms-control policies mean a greater "risk of international confrontation," Carter warned, and "an all-out nuclear arms race" that could "make all the people on earth . . . the losers." Who would vote for that?

"If we succumb to a world of fantasy," he declared, "we will wake up to a nightmare." And who would choose that?

Those were the questions Carter wanted to plant in people's minds tonight -- to plant so deeply they forget whatever doubts they may have about the past, the present and Jimmy Carter.