THERE are two schools of thought about the recent Soviet-American decision to cut off arms to the belligerents in Afghanistan: the pessimists and the optimists.Pessimists believe the Soviet Union and the United States are no longer concerned about the future of Afghanistan. They argue that superpower disengagement is likely to intensify the competition between regional powers to influence events in Afghanistan. Pakistan believes that to resist India's efforts to achieve hegemony in the subcontinent it is essential that pro-Pakistan groups come to power in Kabul. Consequently, it has been promoting the political fortune of Afghan Islamic fundamentalists, particularly Gulbudin Hekmatyar. Iran, too, desires direct influence in Afghanistan. Largely out of concern over the regional balance of power, Iran has been trying to increase its influence in Afghanistan since the end of the Iran-Iraq war, strengthening the military and political position of the Iran-based Afghan Shiite resistance organizations. Saudi Arabia is the other contender. After the US, it has been the largest financial supporter of the mujahideen. When the legitimacy of Saudi leadership was threatened by the Islamic Revolution in Iran, the Afghan war enabled the Saudi leadership to strengthen its Islamic credentials both at home and abroad. Although the ideological threat of the Islamic revolution to the Saudi leadership has almost disappeared, the Saudis are still apprehensive of a strong Iranian influence in Afghanistan. The pessimists believe the superpower involvement in the Afghan conflict had a containing impact on this struggle for influence among regional powers. They argue that without a comprehensive peace, Soviet and US disengagement is likely to lead to a scramble for Afghanistan among the regional powers. As a consequence of the Soviet disengagement, they predict that India will also enter this competition. The result will be more war, killing, destruction, and de facto disintegration of Afghanistan. In contrast, optimists believe that the arms agreement is the strongest indication yet that the superpowers are determined to resolve the conflict politically. Supplying arms to the belligerents has been a contentious issue between the superpowers since 1988. They say the arms cut-off will reduce the intensity of violence and prepare the way for a comprehensive peace mediated by the United Nations. The US-Soviet joint communique seems to support the views of the optimists. The communique endorses the UN's five points statement on Afghanistan, issued on May 21, 1991, and it reiterates Soviet and US support for a political resolution, a cease-fire, and fair general elections. The specificity of the communique suggests the desire for a comprehensive peace in Afghanistan, instead of considering disengagement as the ultimate objective. The superpowers seem to believe that the best way to achieve a compr ehensive peace is to support UN attempts to mediate the final terms of the peace settlement. ALTHOUGH a coordinated US-USSR-UN approach to peace displays a great deal of prudence, there is still a difficult decision about the transitional process. Both the Soviet-American communique and the UN statement talk about the need for a transitional period and a transitional mechanism. Neither document, however, clearly states the nature of the such a mechanism. In the past few years, five different transitional arrangements have been discussed: * A transitional coalition government between the resistance, the Kabul government, and some independent politicians. This approach was supported by the Soviet Union and the Kabul government but was rejected by the resistance. * A resistance-dominated coalition government with minor participation by independent politicians, but excluding the Kabul government. This was supported by the mujahideen, Pakistan, Saudi Arabia, and, until recently, the US, but was rejected by Kabul and Moscow. * A transitional government of nonpartisan Afghan technocrats and independent politicians. This was suggested by the UN and was popular among the supporters of former Afghan King Zahir Shah and high-level bureaucrats in former Afghan governments; it was rejected by the resistance. * A Cambodia-like arrangement whereby the UN will administer major Afghan ministries until general elections can be held to determine the composition of the future government. This approach has not received much attention, but is likely to be rejected by the resistance and the Kabul government. * A brief transitional period, but without a transitional government, to prepare the nation for fair general elections. The Soviet-American communique seems to suggest this approach. Since there is no ideal solution for the transitional period that is acceptable to all, it is counterproductive for the UN to emphasize consensus. This simply grants veto power to the various participants and enables obstructionists to indefinitely postpone the political resolution of the conflict. Any effective peace formula must satisfy some minimum standards of practicality and justice and should be acceptable to a large majority of the people. Such a formula, if supported by the US and the Soviet Union, will prevail and promote the cause of peace in Afghanistan, despite possible opposition from certain groups. It is important to decide soon on the nature of the transitional arrangements and abandon the search for consensus. A prompt resolution of these obstacles to peace will undoubtedly help establish the hopes of the optimists. Otherwise, chaos may dominate and the scramble for Afghanistan could realize the worst expectations of the pessimists.