In a sense, Jesse Jackson won the first primary of 1984 when the editors of Time magazine decided last week to put him on the cover. The black civil rights activist has yet to announce--or perhaps even decide--whether he is seeking the Democratic presidential nomination. But he has gotten something neither Walter Mondale nor John Glenn got with their formal declarations: the cover of Time.

Although a good friend of Jackson's told me last week she would "bet my life" he announces in September, there apparently remain some doubts whether he will actually take the plunge. Questions persist on whether his flamboyant personal style and somewhat sloppy business bookkeeping can stand the scrutiny of a presidential campaign.

Beyond that, there is the question whether the candidacy of the charismatic Chicago preacher will serve to mobilize black voting strength against President Reagan or divide both the black leadership and the Democratic Party in ways that will benefit Reagan.

For those of us in the white community who are watching this internal black debate with fascination and some mystification, there are some helpful pointers in the summer issue of PS, a publication of the American Political Science Association. I was particularly struck by a few paragraphs in an article by Marguerite Ross Barnett, a professor of politics and education at Teachers College, Columbia University, explaining why "opponents and proponents of a black candidacy often talk past each other."

"Although there are exceptions," she said, "in general the most vocal core group of opponents of a black presidential candidacy work mainly within large, nationwide organizations with heterogeneous constituencies. These individuals and organizations operate mainly on the federal level, often with considerable sophistication, are accustomed to and accept compromise as an intrinsic part of politics, and are looking, in most cases, to make an early commitment to a major Democratic Party candidate in hopes of gaining an influential part in the campaign."

When you think of the black mayors, congressmen and leaders of organizations like the National Association for the Advancement of Colored People who have been skeptical of the Jackson candidacy, the description seems to fit.

"Power, to these politicians, is measured by access . . . Up to a point, the threat of a black candidacy may be marginally useful as a bargaining chip in negotiations with one or another political camp . . . (But) black politicians in this faction believe the threat of a black presidential bid is potent only if those making the threat realize it loses impact the minute it is actually attempted.

"For these politicians," Barnett writes, "strategy should only focus on questions of how to exert the maximum leverage with specific front-runners in order to insure patronage and key appointments. The only legitimate participants in such discussions they will acknowledge are recognized politicians. . . ."

Barnett is surely right in suggesting that many of these prominent elected and organizational leaders, with constituencies of their own, resent Jackson's self-promoting tactics and distrust him as the bargaining agent for black interests.

She may also be right in her characterization of the supporters of the effort; these are much less visible on the national level.

"Advocating a black presidential bid," she writes, "are mainly more locally based politicians; the more peripheral, less well-known, less well supported national civic leaders, and a variety of individuals politicized by Reagan administration policies and encouraged by recent victories in Chicago. . . . Joining them have been some leaders from the remnants of the organization formed in 1972 as a result of the National Black Political Convention held in Gary, Ind.

"For the more ideological members of this diverse factional grouping, power often is seen in absolute terms . . . (and) the leverage exerted by the existing black leaders is irrelevant because it is insufficient to produce the kinds of broad-based, sweeping change needed to alter the subordinate condition of the black community."

"Along with the ideological contingent of this faction, however, are many politicians and leaders for whom the threat of a black presidential bid is a useful political tactic to exert leverage on more prominent black political leaders . . . and to increase their own visibility."

It is, she says, part of "an ongoing effort to recast the nature of political and public policy debate; to fundamentally alter the composition of the electorate by adding many more blacks without specific party identification; and to change key institutions in society in ways relevant to positive development of the black community."

What we have, if Barnett is right, is a major power struggle within the black leadership, freighted with consequences for all of America.

That is not a bad story. The editors of Time may have known what they were doing.