Algiers — They came in three-piece pin-stripe suits and Burberry raincoats, toting briefcases, like the professors and bankers and businessmen that a surprising number of them are. There were no outward signs of the cause that brought them here - no army fatigues, red and white kaffiyah headdresses, or guns.
The 350 men and women now assembling in the Algerian capital are members of the Palestine Liberation Organization's parliament-in-exile, officially called the Palestine National Council.
They have come from 90 countries to convene for the first time in two years to decide the strategy of the PLO in the aftermath of the debacle in Beirut at the hands of the Israelis last summer.
It is expected to last 10 days, as militants and moderates within the multifaceted movement attempt to debate their way democratically toward an official response to several key issues: the Reagan Middle East peace plan; relations with the Arab world, particularly with rival Jordan and Syria, who represent the two extremes in tactical and political policy; and military tactics, including terrorism.
Although they do not like to admit it, the Reagan plan clearly overshadows all other issues. The delegates' decision on this could chart the future of the entire 21-nation Arab bloc in terms of peace, since no country will find it politically popular to contradict the guerrilla movement.
The variety of positions here was obvious even before the conference opened Monday, as members of the eight different factions ''leaked'' an equal number of scenarios to the hoards of foreign correspondents assembled to cover what many see as the single most crucial meeting since the PLO was founded in 1964.
''Rejection'' of the Reagan plan, was the recommendation of Abu Iyad, the PLO's No. 2 leader, during the run-up meetings of executive committee members over the weekend. But a spokesman for the Democratic Front for the Liberation of Palestine (DFLP), Abdul Hadi, would only go as far as labeling it ''unacceptable.'' He refused, when pushed, to say rejection. Meanwhile an official of the mainstream Fatah faction conceded there were ''some positive elements'' in the United States initiative.
Delegates surveyed said that it was out of the question to give King Hussein of Jordan the mandate he wants to begin negotiations with the US and Israel. But they all appear to be angry because, as they see it, the PLO as the sole representative of the Palestinians must be part of any legitimate team negotiating for overall peace. The delegates cannot be seen to say otherwise in public without voiding the entire reason for the movement's existence.
Yet in keeping with the Byzantine style of Arab politicking, the average delegate here will also suggest that the Jordanian monarch may eventually join peace talks. They also emphasize the need eventually for an association between a Palestinian homeland and Jordan. The key word is ''eventually.''
At the Club des Pins (Club of Pines) Conference Center on the Mediterranean coast 15 miles outside Algiers, delegates are scheduled to hear all sides, the voices of both the past and the future: a commander of guerrillas who was evacuated last August, a young woman from Shatila camp in Beirut where 800 Palestinian civilians were massacred in September, the Westernized professionals who have not lived the Palestinian experience since the exodus in 1948, the youth groups who represent the militant strains as well as the next generation's leadership.
Reminders of the Palestinians' vulnerability echo through the modern meeting hall. The entrance to the hall is decorated with poster-size photos of last summer's fighting and siege, and the autumn massacre.
They underline the difficult choices now facing the PLO. There is no military option left since neither front-line Jordan nor Syria are prepared to allow guerrillas to launch offensives across their borders. Yet the only valid political option means painful concessions that may lead nowhere and leave the PLO with less than it has now.
Yet after 35 years of conflict and 19 years of PLO struggle, the one fact all accept is that Palestine cannot be ''liberated'' - politically or militarily - by the Palestinians alone. The problem now is who to turn to for help.
Arabs of all political ilks and the East Bloc have little credibility after their performances last summer. In the PLO'S eyes, the US also has little credibility in light of its inability or unwillingness to pressure Israel toward a more moderate position on peace.
The second reality is that the PLO must now do something, since Israel will pave over the Palestinian dream - in the name of new Jewish settlements on the West Bank - if actions is not taken soon.
For this reason, Chairman Yasser Arafat hopes to get a lose enough mandate to finagle behind the scenes in the future. He is looking for a statement that concedes to the increasingly vocal militants by blasting the Reagan plan, but which also reinforces his own position to act in the name of Palestinian interests later concerning all peace proposals.
While the ordeal of last summer underlines the need for peace, it also serves as the biggest rallying point against peace. It is a sensitive time to argue that the PLO should recognize Israel and give up the call for full independent statehood.