Conflicting foreign policy aims, not ideological differences, precipitated the Sino-Soviet dispute, Frank Rendell of the M.I.T. Center for International Studies, said last night at a discussion sponsored by the Harvard chapter of Americans for Reappraisal of Far Eastern Policy.

The crucial snag in Sino-Soviet relations, Rendell contended, came in 1958 over Soviet proposals for a joint fleet in the Pacific. The fleet was part of a comprehensive defense alliance the U.S.S.R. was trying to negotiate with the Chinese. In the months before the proposal on the fleet, the Soviets had made arrangements to establish submarine bases, missile sites, and radar installations on Chinese soil, all to be jointly controlled.

Rendell believes the Soviets' aim was to limit or prevent China's development as a nuclear power. They intended to dominate in the joint control arrangements, and expected China to become militarily dependent upon them as a result.

The basic foreign policy concern of the Chinese, on the other and, was recovery of Taiwan, and they expected any alliance with the Russians to further that aim. But the Russians did not want to risk confrontation with the United States and refused to go along on Taiwan.

Consequently, the Chinese viewed the proposed treaties as serving only the Soviet's interests. Shortly after the joint fleet proposal they denounced Russia's aid overtures as an attempt to gain control of China. The fleet question particularly was anathema to the Chinese because the Soviets had suggested the fleet be based at Port Arthur. "For the Russians to have returned to Port Arthur at this time would have been like the British returning to Boston in 1800," Rendell said.

Rendell describes his novel thesis as an attempt to "reconstruct from nothing." Because the real significance of the failure of the defensive alliance is uncertain the Soviets and Chinese said almost nothing about it publicly.

But the English reporter Edward Crankshaw of The Observer learned about the Sino-Soviet jockeying of 1957 and 1958 from "Eastern European contacts." His account, on which Rendell's theories are based, is in his book Moscow and Peking.