Many Taiwanese prefer the 'authoritarian' China to the 'totalitarian' one

''Taiwan is an authoritarian state, whereas mainland China is a totalitarian state.''

That, said a Taiwanese political scientist, is the essential difference between the mainland ruled by the Communist Party and Taiwan ruled by the Kuomintang, the Chinese Nationalist Party.

Or, as another Taiwanese, a newspaper publisher put it, ''our political freedom is limited, our press is controlled and there are periodic political arrests. But we do have economic and social freedom. We want to keep these freedoms which we have achieved during the past 30 years, and increase our political freedom as well.''

The great fear that many Taiwanese intellectuals have over the possible stoppage of American arms sales to Taiwan is not that this would bring about an immediate communist invasion. Rather, it is that if the United States bows to Peking's pressure and agrees to phase out arms sales to Taiwan, the island's Kuomintang rulers would be shocked into a fortress mentality. The probable result would be an intensification of military and police powers and a narrowing rather than a broadening of political freedoms as exist today.

On the arms sales issue, therefore, there is almost unanimous support on this island for the Chinese Nationalist government's hope that President Reagan will not give way to Peking's demands. Four Taiwan-born, non-Kuomintang legislators are visiting the United States this summer in a campaign to remind the American public that whatever grievances they may have against the government here, they support the need for Taiwan to maintain a sufficient defense capability against possible attack from the mainland.

Friction between the Taiwan-born majority and the mainlanders who fled to the island after the communist victory on the mainland is much less today than during the early years of Kuomintang rule. President Chiang Chingkuo is given credit for bringing Taiwanese into top levels of the government and of the party hierarchy. But the politically dominant role is still played by former mainlanders. They control the Army and the various security services as well.

As one mainland-born, Taiwan-reared political analyst put it, Taiwan today has three principal elements of political power: first, the military, including the security services. Second, the technocrats who have brilliantly managed Taiwan's economy during the past two decades. Third, elected officials.

Former mainlanders are overwhelmingly preponderant in the first group and strongly represented in the second group. But 90 percent of elected officials are Taiwanese. Except for legislators, elections are held only at county and municipal levels for magistrates and mayors. But Taiwanese have been able to use local elections as important rungs on the political ladder. Lin Yangkang, for instance, minister of the interior and former governor of Taiwan province, began his political career as an elected county magistrate.

The Kuomintang itself, at the grass-roots level, must depend upon island-born candidates to carry its electoral banner. With better education and higher socio-economic standards, the Taiwanese electorate is improving to the point where persuasion rather than arbitrary force must increasingly characterize the central government's actions.

There is a large, mostly middle-class Taiwanese community in the US, many of them with PhDs and lobbying effectively for such causes as civil liberties and human rights. ''I think that the Taiwanese community in the United States may have more clout with American legislators than the old China lobby,'' said one prominent Taiwanese journalist.

An independent Taiwan - anathema both to the Kuomintang and to the communists - is the goal of some Taiwanese overseas. On the island, Taiwanese are more circumspect about listing independence as a possible goal. They want a continuous widening of political freedom, under whatever name. They realize that they are 18 million islanders living 100 miles offshore from 1 billion mainland neighbors.

''We can't change the facts of geography,'' said one Taiwanese, ''but at the same time we are very grateful to have those 100 miles of water between us and the mainland.''