SEOUL, NOV. 16 -- South Korea today officially began a presidential campaign that promises to rewrite the nation's history even as it shapes the future.

Six candidates registered to run in the Dec. 16 election, hoping to lead South Korea to its first peaceful transition of power since the republic was born, with the United States as midwife, almost 40 years ago.

"The presidential election is not merely a political event designed to determine which party or candidate wins," President Chun Doo Hwan said today in announcing the date of the election. "It should be regarded as a historic crossroads where the future of the nation will be decided."

The unofficial campaign under way since July already has produced a flowering of debate about subjects that were until recently taboo, including the legitimacy of the current regime and the coup that brought it to power. The debate has heartened many South Koreans, who only six months ago were living in a nation where public questioning of Chun's government was an invitation to a jail term.

Some South Koreans worry that the deep emotions running through the debate may once again drag the nation into a cycle of violence and military coups. Several politicians have suggested that their antagonists should long ago have "slit their bellies in shame;" not only do the candidates represent different policies, they also stand for entirely different visions of the nation's past and future.

Recent violence at rallies of all four major candidates, much of it stemming from regional prejudice in this seemingly homogeneous nation, also has heightened tension. So have the emergence of right-wing groups dedicated to removing "impure elements," continuing sporadic clashes between police and small numbers of left-wing students, and early allegations by opposition leaders that the ruling party is seeking to buy the election.

Most Koreans, nonetheless, seem proud that the process has stayed on track and optimistic that South Korea, an economic prodigy among nations, is also ready to take its place among the world's democracies.

"Our economic power is greater, our education level is higher, so this time we will not fail," one Korean businessman said today. "This time, the hardest part will come after the election."

Two minor candidates, Shin Chong Il and Kim Som Jok, registered today, and a third, South Korea's only woman candidate, Social Democrat Hong Sook Ja, is expected to register Tuesday. But attention focused on the ruling party's Roh Tae Woo and the three Kims.

Roh, who rose to power with Chun in the 1980 coup and is the president's handpicked successor, stunned the nation on June 29 when he went on television to urge Chun to allow a direct election. The concession followed weeks of street protests against the Chun regime.

Roh now presents himself as the candidate of stability and continuing economic growth who established his democratic credentials in one stroke in June. But Roh has been on the defensive recently, having to justify his role in a coup that is being publicly debated for the first time.

Kim Dae Jung, who nearly defeated the ruling party in the last direct election in 1971, is a charismatic opposition figure who inspires the strongest passions, positive and negative, of any candidate. He promised last year that he wouldn't run, since some view him as a divisive force. But now he says overwhelming popular support forced him to reconsider.

Kim said yesterday that Roh cannot win a fair election, but warned that the ruling party appears poised to mobilize government funds and media unfairly. Such cheating would produce a "grave situation," he said.

Kim Young Sam, Kim Dae Jung's fellow opposition leader, is presenting himself as the candidate of the middle class who can deliver democracy without frightening the still-powerful Army.

He also warned against ruling party manipulation today. If either Chun or Roh tries to cheat, he said, that person would "become a second Marcos," referring to the former Philippine president.

Kim Jong Pil, prime minister in the 1960s and 70s, resurfaced after seven years of silence to seek vindication for his role in an earlier authoritarian regime. While the two opposition Kims challenge the official account of Roh and Chun's coup, Kim has been defending his role in Park Chung Hee's government.

The four candidates each represent different provinces of South Korea, and each has offered himself as best able to end regional bias and heal the divisions that have widened during decades of military-installed government.