Jewish voters remain consistently loyal to Democratic Party. Despite rising incomes and other gains, most vote liberal

American Jews, ``confounding logic,'' cling to a liberal voting pattern that puzzles students of politics. A new study by the American Jewish Committee in New York City finds that liberal voting among Jews continues as strong as ever.

Demographers say it would be reasonable to expect that rising incomes, higher levels of education, and increasing assimilation into American society would result in more Jews voting for conservatives. But no such trend has been identified.

In 1986, Jewish support for liberal Democratic candidates, such as Sen. Alan Cranston of California and Gov. Mario Cuomo of New York, ran 25 to 30 percent higher than among the general population.

Although Ronald Reagan picked up 40 percent of the Jewish vote in 1980, he slipped back to a poor 30-70 split in 1984 as Jews reverted to their traditional patterns.

David Singer, director of information and research services for the American Jewish Committee, says that only occasionally is there a break from this ``rock-solid Jewish liberal voting.''

Last year, for example, Republican Senator Arlen Specter, a moderate, got 55 percent of the Jewish vote against liberal Democrat Bob Edgar in Pennsylvania.

Likewise, in New York conservative Republican Sen. Alfonse D'Amato made significant inroads among Jewish voters.

The apparent reason: both men had built strong records of support for Israel and for Soviet Jewry. Those records overcame ideological factors among Jewish voters, Dr. Singer says.

Why the strong liberal tradition?

Several explanations are offered, but Singer says none of them is entirely satisfactory.

Some analysts have suggested that Jewish liberalism is a carryover from the European experience. In Europe, it was the extreme right, such as the Nazis, which threatened the freedoms, and the lives, of Jews. It was liberals who fought for Jewish integration and acceptance.

Others say the most ready explanation is Jewish tradition, which is inherently liberal in nature.

``The problem with that reasoning,'' says Singer, ``is that those Jews who seem most traditional tend to be those who are least liberal.''

Orthodox Jews, for example, have a more conservative voting pattern than Reform Jews.

A third possible reason: the failure of Jews to be fully integrated into American society.

Despite their financial and educational progress, many Jews still feel outside the mainstream, it is argued. This causes them to side with those politicians, such as liberal Democrats, for whom civil rights is a top priority.

Although no single reason stands out for Jewish liberalism, the 1984 election offered at least one insight.

Prior to the summer of 1984, President Reagan and Walter Mondale were splitting the Jewish vote, approximately 50-50, in the polls. However, during the Republican convention in Dallas, the President made an overt appeal to fundamentalist Christians.

Many Jews were frightened. Conservative Christians were pushing to have their religious beliefs put into law: a ban on abortions, prayer in the public schools, tax exemptions for segregated schools.

Beginning in August, there was a rapid drop in Jewish support for the President.

On election day, an ABC-TV exit poll found that 20 percent of Jewish voters said that the support of the fundamentalist Moral Majority for Mr. Reagan was a key factor in their support of Democrat Mondale.

This sharp reaction indicates that if Republicans are to expand their support among Jews, the GOP must be much more sensitive to issues which Jews perceive as potential threats to their freedom.

While Jews comprise only 3 percent of the US population, they contribute 5 percent of the vote because of high levels of turnout.