THE deserted beaches on Yugoslavia's Adriatic shore are mute witnesses of a once viable state's self-destruction.For years, foreigners spending hard currency filled those beaches, during July and August - 8 million of them in 1990. This summer's count is only tens of thousands. At the height of summer, 24 of 30 top flight hotels in Dubrovnik - jewel of the Yugoslav littoral - were closed. All along the coast, hundreds of small bistros and restaurants have gone bankrupt. The breakdown in tourism will cost Yugoslavia $4 billion. Overall, ethnic violence is costing the country $30 billion. The national economy, in fact, has already virtually disintegrated, although regional economies are still struggling along. This year the gross national product and industrial output will be down 20 and 30 percent respectively. A quarter of Yugoslavia's 24 million people already live at or below the poverty line. One in three workers earns less than the monthly national average of $350. Unemployment is nearing 2 million. Such poverty is fueling the country's social unrest. The secessionist republics of Slovenia and Croatia already figure losses at $3 billion and $4 billion respectively. Forty percent of Slovenes polled once urged "greater care" and more negotiation before independence. As the Croatian fighting escalated last month, one Zagreb resident remarked despairingly: "I am a Croat, but I am also a Yugoslav and I want to stay in Yugoslavia." Protest at the senseless loss of life is mounting. Serbia finally made a first concession by agreeing to international monitoring of a cease-fire. The European Community is holding a first round of peace talks in The Hague, the Dutch seat of government, this weekend. It is too early for hope. But international monitoring of a cease-fire may be a first step toward halting military conflict. It may also encourage Yugoslavs to call for a sense of responsibility and willingness to cooperate as the only way to avert all-out ethnic war and economic disaster. The lack of such a sense brought about the present impasse. Milovan Djilas, Yugoslavia's first dissident, who helped draft its Constitution after World War II, has said it was not a perfect solution, but in its time it was a good one. Each republic had an independent government and parliament and drafted its own budget, subject to the interests of the central government. Common interest, however, was rapidly sacrificed to local ambitions after the passing of President Josip Broz Tito. Undoubtedly, Serbia's policy of suppressing ethnic differences, and exposure of its dream for a "greater Serbia" spurred Slovene and Croat desires for independence, though both need a broader Yugoslav market. Slovenia, having in theory already achieved a fragile independence, is momentarily on the sidelines. International attention is focused on the conflict between Serbs and Croats, where uncompromising leaders have failed to calm violence. Both leaders represent extremes: Serbia's Slobodan Milosevic represents anti-pluralist, nationalist communism; Croatia's Franjo Tudjman wants to reserve "Croatia for Croats." Neither position bodes well for Yugoslavia. Perhaps the threat of a Soviet disintegration will call into question the gains of a breakup, and prompt all Yugoslavs to consider compromise. Yugoslavs can expect no easy answers by early acceptance into the European Community. The Baltic states will get preference and the EC will be in no hurry for further expansion. A new confederation can still be devised enshrining the basic principles of equality, but improving on the old federation with better reasons for holding together. The reasons are constitutional guarantees of domestic economic and social sovereignty, and joint obligation to ensure the nation's future. But it will require the common sense of responsibility which so far has been in such short supply.