(FORTUNE Magazine) – WILL PERESTROIKA work? When Abel G. Aganbegyan, 56, chief economic adviser to Soviet leader Mikhail Gorbachev, was recently asked that awkward but unavoidable question, a smile flickered across his normally impassive face. ''In the Soviet Union we have a saying,'' he replied. ''A pessimist is someone who believes things can't get any worse. An optimist thinks maybe they can.'' By his own wry definition, this loyal socialist with the body of a bear and the eyes of a raccoon has been a lifelong optimist -- that is, a stubborn worrier over his country's economic future. As a student at the Moscow State Institute of Economics, Aganbegyan defied his Stalinist supervisors and taught himself statistics in order to gain an independent view of how the Soviet economy really worked. During the 1960s he was a supporter of Prime Minister Alexei Kosygin's attempts to reduce the power of Moscow central planners. When Kosygin's reforms failed to take root, Aganbegyan, the director of the Institute of Economics in Novosibirsk, Siberia, provided a refuge for economists and sociologists frustrated with the stagnation of the Brezhnev years. In 1981 a colleague introduced him to a Communist Party hotshot named Mikhail S. Gorbachev, who shared Aganbegyan's enthusiasm for using market mechanisms, such as competition, to make socialism more efficient. When Gorbachev took power four years later, Aganbegyan and his Novosibirsk gang were called to Moscow to put their theories into practice. Aganbegyan's biggest fear is that the pocketbook payoff from perestroika is coming too slowly. Says he: ''The spiritual changes from glasnost are visible every day, but the vast majority of Soviet families have not seen positive changes in their material welfare.'' Worse still, because most workers' incomes have been increasing faster than Soviet output, inflationary pressures -- reflected in rising black market prices -- are building. To buy time, Aganbegyan and other members of Gorbachev's economic brain trust last summer persuaded the General Secretary to make a significant midcourse correction in the current five-year plan. Among other measures, government investment in housing construction and consumer goods industries will rise sharply. To put more food on the shelves quickly, agricultural cooperatives will be encouraged to take out long-term leases on state-owned land -- a back-door method of breaking up the Soviet Union's notoriously inefficient collective farms. If the Soviet economy remains stalled, Gorbachev's guru could eventually fall from favor. Already some Kremlin watchers note that despite his publicized trips abroad, Aganbegyan's profile as perestroika's pitchman at home has been low lately. But he maintains that the reforms will get more time. Says he: ''Our move from a dictatorship of producers to an economy driven more by consumer demands has barely begun. The next three years should show whether we will have a success.''