Don't shoot down diplomacy

Neither British nor Argentine officials are letting the weekend's military combat finish hopes for a negotiated settlement of the Falkland Islands dispute. Indeed, the need for such settlement becomes the more urgent in order to forestall additional fighting. A solution by force would be no solution at all, simply opening the way for more years of conflict.

Thus it is important that this week's meeting of the Organization of American States be part of a broader international effort supportive of negotiated resolution. This effort ought to draw on the full possibilities of the United Nations, as leaders of the loyal opposition in Britain have been advocating even while backing the Thatcher government's display of might. One specific proposal worth considering is UN administration of the Falklands during a sorting-out period minus military maneuverings.

This is not to count out the good offices of the United States. It has worked hard to keep a dialogue going. It can still be of help. But the broader the context of concern the better.

Argentine Foreign Minister Costa Mendez may have canceled a weekend meeting with US Secretary of State Haig after the British retaking of South Georgia. He may have said the two countries were then technically at war. But he also said, ''There is never an end to diplomacy.'' This attitude can be built upon, along with similar sentiments from the British side.

The prospect must be kept open for a legal procedure such as referral to the International Court of Justice, as Britain suggested to Argentina in 1948. Think of the trouble that might have been saved by such joint commitment then. It is not too late to try again.

The necessity is to return to where matters stood before Argentina flew in the face of international law by using aggression to assert its claim to sovereignty over the Falklands. This claim was supported by the Inter-American Juridical Committee of the OAS as long ago as 1976. But Argentina has let down the OAS by violating Article I of the very Rio Pact it is invoking against Britain. This article pledges the parties to undertake their international relations without resort to the threat or the use of force in any manner inconsistent with the UN charter.

Argentina could not cite the charter's Article 51 on the ''inherent right'' of self-defense in the face of armed attack. It was not under attack when it seized the Falklands. Yet Britain can and does cite that article in its use of force to recapture South Georgia, a Falkland dependency, after Argentina had taken it by force.

Let the cycle of violence stop here.