The Democrats and dual primaries

JESSE Jackson's presidential candidacy is presenting the Democrats with dilemma after dilemma. Out of this could come creative ferment for the party. On the downside, it's at least deeply nettling.

The Rev. Mr. Jackson's foreign policy positions, on South Africa and the Middle East particularly, lie outside the party's activist consensus. The preacherly way Mr. Jackson formulates things and, to be candid, his color, have made his opponents and Democratic professionals self-conscious in dealing with him.

All this comes to bear on Jackson's list of complaints about his party's current political system. Jackson wants to end the double or runoff primary for state and federal offices in some 10 Southern states. He wants a change in national-convention delegate rules - ending winner-take-all or winner-take-most provisions, and replacing caucuses with straight proportional primaries for apportioning delegates to the national convention.

Jackson has been leaning heavily on Walter Mondale to endorse a lawsuit in Mississippi federal court that would banish the runoff primary under the Voting Rights Act. Gary Hart has joined Jackson, who has made such support a nonnegotiable condition for his backing of an eventual Democratic nominee.

The trouble with Jackson's case about the double primary is that there is little empirical evidence of its impact on black candidacies. In some elections, it apparently does discriminate against blacks. In a field of several whites and a black, whites will divide their votes among whites; in a runoff with a white against a black, whites vote for the white. Says Washington political scientist Austin Ranney: Ending the runoff primary would likely mean many more black candidates, and a handful more blacks elected, but the largest gain would be in Republican victories.

The Voting Rights Act considers the discriminatory consequences of election practices, not just the intent of those who set up the practices. Hence the argument that the Southern runoffs were set up early in the 1900s before blacks became a political force, and thus were not intended to discriminate against blacks, may be beside the point. In the one-party South, a primary runoff was meant to bring order to an often chaotic process and stage a meaningful election , since the final against a Republican was a mere formality.

Some black candidates in the South - an Andrew Young or Julian Bond in Atlanta - have managed to do well under the current system by mobilizing the black constituency and appealing to the moderate white community.

The Reagan administration has joined the Jackson lawsuit to challenge the runoff primary. This highlights the issue this election year for the GOP's benefit.

Nonetheless, Mondale and the Democratic leadership should support the suit, at least to find out whether it is applicable in all jurisdictions. As in school desegregation decisions, the review of evidence by courts has been the only way through the walls of resistance and argument about motives and facts. If the ruling goes against any jurisdictions, they should pledge enforcement. And the party should review the issue on its own.

But primary runoffs are not in themselves discriminatory. Runoffs can whittle down a large field to the broader-appealing candidates. They lessen the chance of an extremist candidate sneaking in. A blanket ban on runoffs does not seem necessary or wise.