THE DEMOCRATS never fail us. What looked bound to be, just a few months back, a world-class dull, coronation-style convention has acquired all the classic attributes of a Democratic brawl: drama, uncertainty, spite, cynicism cloaked in high-minded rhetoric, and widespread refusal of any side to take the other's professions of serious intent or good faith seriously. It should be fun.

It is, in the first place, High Noon for everyone . We'll take that further. It is High Noon for everything . A decade of procedural reformation (some of it pretty crazy, but never mind) is in danger of being chucked out. Some 19 million voters participated in this year's "reformed" primaries and caucuses to have their say in selecting the party's presidential candidate, and the federal government, under reform-law, ponied up around $7.5 million in matching funds to enable the Kennedy and Carter campaigns to perform their grass-roots labors. Now the question before the convention is whether to vote to undo this costly and elaborate handiwork and let the more traditional and normal life forces of a political gathering decide what the voters had thought they were deciding. That, not freedom from oppression, is the real rules fight issue, and it is frankly more interesting when looked at this way than when it is dolled up as a civil liberties question. Maybe the time has come to end the strange depoliticizing-of-politics trip the Democrats embarked in the mid-'60s. Has it?

And what of the substantive issues of foreign policy and economy? Will the Democratic Party try to stay faithful to old and honorable ideals and principles by staying stubbornly and wrongly faithful to various programs and policies that have proven unable to fulfill those ideals? Will it be a programmatic nostalgia bath, a renewal of nuptial vows with failure? Or will the party seek to show the steadfastness of its commitment to its social and political values by having the guts to admit failure where it has occurred and trying to formulate new and relevant answers to the pressures of today's world? Tune in Tuesday (platform) night.

Sen. Kennedy's fate is intricately involved in both the rules and substantive issues fights, and for him, no less than Jimmy Carter, this is It. The week could in effect mark the end of more than a decade of expectation and assumption, shared by Mr. Kennedy's admirers and antagonists and all those in between, that he had a presidential destiny. This supposition has kept countless other Democrats from entering the competition, and if Sen. Kennedy is out in a serious way, they will henceforth be in. The result for him will be determined not just by winning or losing the rules fight. If he should lose it, how he conducts himself in response could have a large impact on both his future and that of the Democratic Party. There is talk that, losing, he would elegantly retire from the contest the following night, in a glory of issues-talk and platform exhortation and urge his delegates to . . . to do what?

So. You thought we'd never get to Jimmy Carter. But here we are. Talk about High Noon. The wisdom, which changes every hour on the hour, has it now that a Carter victory on the rules fight and a Kennedy step-down the following night will sew it up for the president. We'll wait and see. It isn't a hundred percent obvious to us that with some 1,200-plus Kennedy delegates suddenly freed, for instance, the thing would automatically revert to Jimmy Carter -- even if Sen. Kennedy had urged his delegates to go that way. And what exactly would the enacted rule be worth in practical terms if, for example, a hefty and noticeable group of delegates was formed to violate it during the voting and dare the Carter forces to remove its members one by one from the convention floor and send in "replacements"?

Mr. Carter is under terrible challenge. Sizable forces in his party want to throw him out. He is dismal in the polls. He is said to have the votes at the convention, the "numbers," and there is some realization that if he were to repudiated, especially by a last-minute changed rule or an open rebellion led by "bosses," the party would have as little chance without him as his antagonists think it now has with him. There are half a dozen so-called scenarios that could unfold in the next several days. All are turbulent -- great news for Republicans, journalists and other assorted busybodies. None is especially happy from the Democrats' point of view.