One cheer for President Chun Doo Hwan, who has changed his style of dealing with South Korea's political opposition. He decided that a heavy hand only alienated Koreans and aggravated foreign concern, especially in the United States.

Over the weekend, President Chun permitted 50,000 people to conduct an antigovernment rally -- in Kwangju no less, a place where he embittered many citizens with a bloody crackdown on protesters in 1980. Opposition leader Kim Dae Jung was barred -- he should not have been -- but others spoke and the crowd chanted "down with dictatorship." Only when the crowd disbanded did some students and police clash.

President Chun is wise to prevent official repression from rubbing politics raw. But the grievance at the heart of the crisis remains untreated. Then a general, he took power in 1980 and wrote a new constitution. Under it, a successor is to be elected, to a seven-year term, in 1988; it would be South Korea's first peaceful transfer of power. But the constitution, providing for indirect voting by electors, ensures that the president will be able to handpick his successor. It rules out an amendment to allow popular election until the president is in office. Amend the constitution now, says the opposition. No, says the government, wait at least until 1989.

Given the calendar, the opposition's amendment campaign would have started up now anyway. There's no doubt, however, that the surge to democracy in Manila has made an impact. That Washington ended up supporting the Philippine movement has both encouraged the opposition in Seoul and sobered the government.

The authorities in Seoul point out that, unlike the Philippines, South Korea is a relatively well- run, forward-looking society and has a deadly foe poised on its border ready to exploit domeic unrest. They warn that the amendment campaign is "a cover . . . to bring about the overthrow of the existing constitutional order." But this is hardly so. In Korea, traditional favor for order and conformity may "coexist uneasily with Western democratic ideals," as the State Department suggests. But an appreciation of complexity cannot be allowed to rationalize police rule. Koreans, an increasingly confident and sophisticated society, are surely competent to run their own affairs.

It falls to President Chun to manage political modernization in a country where economic and social modernization is well along. A peaceful demand for constitutional revision cannot be ignored. A method of governance that freezes out millions of people for 10 or 15 years is a recipe for the instability that the Koreans wish to avoid.