A NEWLY formed Soviet parliament, uncertain of its role or powers and half-formed in its membership, convened yesterday in the Kremlin.Soviet President Mikhail Gorbachev sat in his usual spot to the right of the chairman's dais, leaning forward to peer at the largely new set of faces in the chamber. The old parliament had dissolved itself in September following the failed coup. The new body is formed entirely of members sent by the republics. Mr. Gorbachev tried his best to imbue this parliament, one of the few institutions where he has a role left to play, with some new meaning. In a brief, businesslike speech, the Soviet leader called on the parliament to preserve the union and laid out tasks before it. "Will we go forward together, or will every republic try to find its own way?" Gorbachev asked rhetorically. "Until we clear up this point, all programs will remain just wishful thinking. We'll remain stuck while the tension in society will continue to grow." Gorbachev's view was clear. "Some are for maintaining the old super-centralized totalitarian state, others for an economic union without a political union. There is the opinion that the union no longer exists and we should go to the end in separating and disintegration. I'm convinced that if any one of these points of view prevails, the consequences will be catastrophic for all peoples and republics." But a simple count of republics represented at this opening session signaled more than the speech about the problems besetting a union of any kind in this country. Of 12 republics still considered part of the Soviet Union, only seven sent representatives to the new body. Russia, Byelorussia, Kazakhstan, Turkmenia, Kirghizia, Uzbekistan, and Tadzhikistan attended, but one-third of the delegates from those republics did not even bother to attend yesterday's session. The powerful Ukraine opted out entirely, along with the three Caucasus republics of Georgia, Armenia, and Azerbaijan, as well as Moldavia. Asked why the Ukraine was not participating, the permanent Ukrainian representative in Moscow, Vladimir Krizhinovsky replied: "Why isn't the French delegation here? We are an independent country." Even those who did come to the new Supreme Soviet, as the parliament is still called, were far from certain of its purpose. "That is the most enigmatic question - nobody knows [the answer]," responded Vladimir Lukin, who heads the foreign affairs committee of the Russian republic parliament and is a member of the new Soviet parliament. "Juridically speaking, this is a rather questionable assembly," commented economist Nikolai Petrakov, a deputy from Russia and an adviser to President Gorbachev. "But," he added, "we should still have some body in which we can discuss things, just like the European parliament." The comparison to the European parliament, the elected but largely powerless legislature of the European Community (EC), was made by several delegates in hallway conversations. At least eight republics - the seven attending the parliament plus Armenia - have agreed to form an economic community, signing a treaty to that effect on Friday. The treaty gives legitimacy to the State Council, which includes the republican leaders and Gorbachev, and to the inter-republican economic committee. Gorbachev, in his address, supported moves toward market reform pushed by the inter-republican committee. He called for parliament to back economic reform that includes: halting the breakup of the Soviet monetary system; stabilizing the ruble; moving rapidly toward privatization and free-market pricing; and encouraging private entrepreneurship. He also called for business tax breaks, land reform, and reorganization of the Soviet international trade system. The Soviet president drew little reaction - and no applause - except when he sharply attacked republics for trying to set up their own national armies and for trying to "nationalize" Soviet Army units and equipment on their territory. Such attempts "should be considered ridiculous, irresponsible, even illegal," Gorbachev said, threatening to take "constitutional measures" against such moves, a statement that provoked a ripple through the hall. But his plea for political union seems likely to fall on deaf ears though the economic community will undoubtedly take some political form. As Mr. Lukin put it, "It is impossible to completely divide economic and political things because economic ties presume coordination."