THERE IS A question mark over the South Korean elections, but on the evidence so far, Roh Tae Woo, the ruling party's candidate, won a healthy plurality. He won playing by the opposition's rules: it had demanded a change from indirect to direct elections, and it got it. The air is thick with complaints of fraud, but the proof offered so far is thin. Some in the opposition claim the fraud was sufficient to invalidate the results. The more convincing explanation appears to be that the opposition lost because it split its vote among three other candidates, including the two Kims, whose combined vote did in fact exceed Mr. Roh's. Also, Mr. Roh ran a good campaign, presenting himself as a repentant former general who was now reliably committed to reform.

In this immediate postelection period, Koreans are ''voting'' a second time. This time the question is whether to accept the outcome of the balloting. Here it is useful to recall that the military-dominated ruling party was forced to move last spring from indirect elections to direct because the country's burgeoning middle class joined the students in the streets to demand the change. An impulse for democracy and stability, in tandem, carried the day. There is the chance that the same impulse may keep the middle class out of the streets now. These are people who prize the progress Korea has made in its development and crave a political result to match, but fear to invite disorder. Presumably, this group includes not only most of those who voted for Mr. Roh, but also -- potentially -- at least some portion of those who voted for the two Kims.

The opposition, in its ambition and ardor, is working to keep the United States from accepting the election as fair and legitimate. It declares that American approval of a Roh victory will identify the United States with a repressive self-perpetuating military caste and stir the not-so-smoldering embers of anti-Americanism in Korea. But of course the United States cannot be intimidated by propaganda. If it determines that the election was reasonably fair, then it has good reason to say so -- and to suppose that Koreans will come to the same judgment themselves.