SHOULD THE United States resume arms sales to Argentina and Chile, countries proscribed as a result of their human rights violations in the 1970s? Neither needs the arms for any special military purpose: they both are at peace externally, and like most other Third World Countries formally dependent on American arms, they have reacted to American human rights policy by diversifying their arms suppliers. Still, the military governments in Buenos Aires and Santiago do covet the stamp of political approval that a resumption of American arms sales would confer.

In respect to Chile, the decision is easy. The threat, in whose name the military took power 10 years ago, has long since been exorcised, and yet the generals cling to power and bludgeon citizens whose claims pose not the slightest risk to its power. The official Chilean sponsors of the murder, on a Washington street, of a Chilean exile remain at large. The wife of the dictator took tea with Mrs. Reagan at the White House last year--a shocking dereliction of political taste. To go further and reward an unregenerate regime with arms should be unthinkable.

Argentina is the hard case. The passage of time and the perceived need to win back some of the status it lost in the Falklands has led the military regime in Buenos Aires to ease up on its own people. To reward that improvement and encourage more is the reason cited for putting Argentina back on the approved list. But this is the regime that killed or made to "disappear" thousands of citizens it never found guilty of any crime. In Latin America and elsewhere, a gesture of favor by Washington now might be taken as a sign to the generals that they need not complete the movement they have announced toward a return to civilian rule.

Both Chile and Argentina are on that list of "authoritarian" countries that the Reagan administration has seen as internally imperfect yet open to improvement and meanwhile useful in the international anticommunist cause. Yet no general theory should be allowed to obscure the particulars that ought to guide human rights decisions. The American interest here lies in using what political and moral leverage the United States has to encourage a return to the democratic fold. Neither in Chile nor in Argentina are there currently any extraneous international factors requiring Washington to swerve from that course.