Argentina's example

Argentina's vigorous return to democracy should have an important leavening effect throughout South America. Nations already moving toward a similar shift from authoritarian to elected government, such as Brazil and Uruguay, will find that Argentina's example produces both pressure and encouragement to speed the move. And there will be modest pressure for a shift to democratically chosen government in nations, like Chile, where there is little sign now of a move away from military rule.

After almost eight years of military rule in Argentina, the mere return of elected government is encouraging to supporters of democracy throughout the continent. Additional encouragement comes from the forcefulness with which President Raul Alfonsin is moving to tackle the nation's major challenges, from the economy to foreign affairs.

Most recently he has promised to take action against past junta leaders and others he holds accountable for the ''terror, pain, and death'' he said stalked his country during authoritarian rule. If he is able to keep moving forward quickly, as he desires, it will be evidence that democracy can effectively deal with the problems left in the wake of military governments. And one effect will be to nudge other nations more strongly toward a return to civilian government.

Brazil is already partway down that road. Last year it held legislative and municipal elections; it is scheduled to hold presidential elections in 1984 or ' 85. At present, however, the ruling military is focusing on its $90 billion international debt, with the planned return to civilian rule at least temporarily in the background.

In Uruguay, elections have been planned for 1985, but there now is some question whether the military will permit them.

It is unlikely that in the near future Chile's military rulers will move toward a restoration of civilian rule, as called for this week by a rally of Christian Democrats from 15 nations, meeting in Santiago, Chile. But even there a successful Argentine example, coupled with internal pressure from the Chilean opposition, can be expected to have a long-term effect.