One could lose one's credibility by showing optimism over the current Lancaster House negotiations in London to resolve the Zimbabwe problem. Nevertheless, recent discussions with a cross section of participants there have led this longtime observer of Zimbabwean affairs to be guardedly optimistic that, in spite of possible stumbling blocks and disruptions, the conference will produce positive results.

Five key ingredients are present. First, all the parties have made compromises from their longstanding positions. They will continue to do so as long as they feel comfortable that their opponents are also being forced to make compromises and that the British, as the fulcrum upon which the future of each is dependent, are acting fairly.

Second, no party is prepared to be perceived as walking out of the conference unilaterally. The multinational and multiracial way by which the Commonwealth, under the farsighted guidance of Secretary General Shridath Ramphal, has crafted general guidance and assigned the British the responsibility for seeking the solution has made it difficult for any of the parties to gain international sympathy if they were to act to undercut progress. The interests of important outside nations further buttress this. A Conservative government in the United Kingdom has combined with the front-line states, especially the governments of Tanzania and Zambia, to make it clear to the Zimbabwean parties and interests who rely on each of them that now is the time for solution rather than continuation and that undercutting a reasonable solution would lead to removal of hopes for international support.

Third, Zimbabweans continue to die in the war. Supporters of all sides are dying. Regardless of the level of those deaths, it is clear that no side can be comfortable to see its supporters continue to die, its fellow citizens continue to die. All have begun to realize that a continuation of such deaths could undercut their efforts in a protracted struggle.

Fourth, there is reason to think as well that each of the three major black parties -- those of Muzorewa, Nkomo and Mugabe -- believes that with the proper election assurances it could win the election. That too is a hopeful sign.

Finally, the British have a little more leverage under the Thatcher government than they had previously. No one doubts that Margaret Thatcher could lift sanctions if she wanted to. The Patriotic Front does not want to see that happen. At the same time, she can control the Conservative Party's right wing, the traditional support of first the whites and now the Muzorewa government. That effectively limits the range of pressures available to that group in dealing with the British. All sides must treat the British with care.

The above observations are not meant to minimize the difficulties of identifying the specifics of any future compromise, because the parties do differ significantly. But it does provide reason to be hopeful.

Constitutional arrangements alone will not resolve the differences. New elections will be necessary. The transition period before new elections, a new constitution and its new structures will come into existence may require that the current government give way to some kind of neutral presence. Sadly, no two sides of this many-sided problem trust one another. It would be very difficult for Muzorewa to agree to turn the control of government to someone else. The willingness to do so may be his strongest bargaining chip. But outside oversight may be needed. For such oversight to be exclusively British may be unacceptable to all the parties. In fact, the lack of trust that the parties show for one another is equally shown by each of the parties toward the British. The Commonwealth may have to stand ready to jump into the breach to put forward its own administrative and security force to provide the necessary transition.

How long will the conference go on? The British publicly had hoped that the conference might have been over by now. No one could possibly have believed that possible. Muzorewa had indicated that he was prepared to go home by now but has wisely reneged on that. Under the best of conditions, after a couple of more weeks the general outlines of both the constitution, a transition period and the structure of security forces should be agreed upon. Thereafter, the conference can be recessed and working groups created to negotiate specifics. Such working groups would be composed of the extremely able lieutenants whom the parties have with them in London. By about mid-December the expanded details should have been developed by the working groups and the conference can be reconvened, it is hoped, with the intention of having an agreed-upon process by the end of January 1980. Then a transition would begin that could last anywhere between three months and 15 months.

Even if this unusually optimistic view prevails, however, clouds remain. The British seem determined more to "get the monkey off their back" than to devise a permanent solution. It is hard to envision a Zimbabwean body politic in which the conflicting leaders and parties work together and where losers in an election accept the rule of the winner. Some have already indicated that further changes might be necessary after independence.

Perhaps it is too much to expect the next stage to be permanent. The minimal goal ought to be to see to it that structures are set up to allow the people of Zimbabwe to choose their leaders, to permit the potential leaders to form their coalitions and to ensure that international forces that wish to exert their own parochial interests are constrained from doing so under the watchful eyes of the concerned public and the careful oversight of the Commonwealth.