While opening his 1980 campaign with familiar hard-nosed tactics, Jimmy Carter visited this city, where past admirers have been few, to find his status magically elevated by the 17 days of Ronald Reagan's ordeal.

Those same Philadelphia Democrats who had buried President Carter are now rushing to embrace his resurrected person. It is not that they have any greater love for him or any greater respect for his ability. It is merely that they now consider Carter a winner, thanks to Ronald Reagan's blunder-a-day indiscipline.

Carter himself has remorselessly sought to hasten Reagan's decline. Addressing a predominantly black audience at the Zion Baptist Church here, he contented himself with one blast at Reagan, attacking him for "suggesting" that the social security system be made "voluntary." Although the charge is dubious, it pales before what the president did a day earlier in Independence, Mo.: he branded Reagan an enemy of peace, the working man and the South, incorrectly claiming that he had announced a "massive" nuclear arms race.

This all adds up to the Carter who is remarkably similar to the Carter who beat down Carl Saunders in 1970 and Teddy Kennedy in 1980. While avoiding clear ideological identification, the president engages in hyperbole when attacking his opponent that has been his political trademark.

Carter's Philadelphia trip was supposed to be an off-day from pummeling Reagan. But the one blow gives a good idea of the president's technique. Reagan's most recent clear statement that Social Security ought to be "voluntary" was made by him in the mid-1960s. His Fedbruary 1976 implication that he would consider such a change was immediately regarded by his advisers as a blunder, and it has not been repeated.

At independence, Carter reached into his bag of gothic southern hyperbole and said of Reagan: "He has announced that if he's elected president, that he will initiate a massive nuclear arms race against the Soviet Union." Of course, no such announcement was made. Carter presumably was enlarging on the Republican Party's pledge of "military superiority."

This is an old political tactic, particularly identified with Carter: caricature of the opponent's position comes to be the common perception if repeated often enough. While attacking his foe, Carter deflects any issue where a firm, unequivocal position would hurt him.

Thus, at the Independence "town meeting," Carter dodged a question about school prayer -- a vital matter to millions of born-again Christians. "The thing that I'm against, as president and as a Baptist, coincidentally," he said, "is the government telling people they have to worship at a certain time and in a certain way." But that is not the issue. The Supreme Court has prohibited voluntary, nondenominational prayer, which Carter says he approves. As with abortion in 1976, Carter straddles the school-prayer question.

The Carter method left the Independence "town meeting" participants less than inspired. Although the black audience in Philadelphia was spirited, the president's midday visit to the Italian Market here generated a small, unresponsive crowd.

Nor are Democratic politicians here truly enthusiastic. "In all seriousness," one prominent Democrat who reluctantly supports the president confided to us, "I can think of 100 men and women right here in Philadelphia better equipped to be president." That was the judgment of Philadelphia voters who favored Sen. Edward Kennedy nearly 2-to-1 over the president in this year's primary.

But Mayer William Green, who endorsed Kennedy in the primary, was at Carter's side all day campaigning in Philadelphia. The president reported at the Zion Baptist Church that he had just talked to Kennedy himself on the telephone. Delayed federal grants are miraculously unblocked; a federal agency destined for transfer to Americus, Ga., will stay after all. a

The lone seeming holdout is popular young District Attorney Edward Rendell, an ardent Kennedy backer. He skipped the president's visit here. But one small sign of Carter's commitment to urban America will bring in Rendell. That probably will be restoration of a canceled drug enforcement task force for Philadelphia.

In truth, Rendell and many other Kennedy Democrats had the wits scared out of them during 17 days of exotic Reagan remarks on subjects ranging from Taiwan to evolution to the Ku Klux Klan. That explains both Carter's resurgence and his ability to misrepresent Reagan's positions and cloud his own positions without undue scrutiny. The presidential campaign so far boils down to whether Ronald Reagan can discipline himself sufficiently to make the president share the unwanted spotlight of critical attention.

The Aug. 25 meeting of congressional surrogates for Reagan was addressed by Tony Dolan, not Terry Dolan, as we incorrectly reported in Wednesday's column.