More than half the public has not heard or read about the Supreme Court nomination of Robert H. Bork, but those who have are sharply divided over whether he should be confirmed, according to a Washington Post-ABC News survey.

Of those aware of the nomination, 45 percent said they approve and 40 percent disapprove, with 15 percent undecided. However, 55 percent of the 1,205 adults interviewed said they had not "read or heard anything" about the controversial nomination.

According to the poll, 4 percent of those aware of the nomination said Bork is liberal or very liberal; 6 percent identified him as moderate; 29 percent as conservative, and 26 percent as very conservative. The remaining 35 percent did not characterize him.

The poll indicates that people who consider him a "moderate" or "conservative" approve of his nomination. More than seven of 10 of those who put him in those categories support his appointment. His supporters generally said they think that intellectual qualifications, not political views, are what the Senate should consider.

By contrast, four out of five of those who called him "very conservative" disapprove of the nomination. Bork's opponents generally said they think that the Senate should take ideology into account in assessing the nomination.

Because so many people have not heard about the nomination and opinions may not have hardened, both sides have the opportunity to sway the undecided majority. The results suggest that the key to the public debate over Bork will be whether he is viewed as an "extremist" or simply a conservative closer to the judicial mainstream. The Reagan administration contends he is in the mainstream; Bork's leading opponents disagree.

The White House has stressed Bork's intellect and argued that he is a fair-minded moderate conservative along the lines of retired justice Lewis F. Powell Jr., whom he has been nominated to succeed. But opponents studying Bork's speeches and five-year record on the federal appeals court here insist that he is a doctrinaire conservative.

Public Citizen Litigation Group, a consumer organization founded by Ralph Nader, issued a study yesterday concluding that Bork has no clear judicial philosophy except consistent suport for government or business and opposition to consumers, labor, environmentalists and political demonstrators.

William B. Schultz, who directed the study, said the 123-page report "concludes that in close cases Judge Bork's votes can be predicted with almost 100 percent certainty simply by identifying the parties to the lawsuit. Judge Bork's votes cannot be explained by the consistent application of judicial restraint or any other judicial philosophy."

The study, which focused on 56 split decisions in which Bork voted, found that he voted against allowing groups and individuals access to judicial determinations of their complaints in all 14 cases where the appeals court was divided on the issue.

Bork voted nearly every time against consumers, labor and environmental groups when they sued the government, according to the study, but always voted for business when it contested government regulators.

"If the White House wants to come out and say he is predetermined in all his views and that he's going to vote for business, and we are entitled to have someone like that confirmed, that's perfectly all right," said Alan B. Morrison, another attorney who worked on the study. "We'll debate them on that issue. But if you are looking for a moderate, you're not going to find one in Robert H. Bork."

Justice Department spokesman Patrick S. Korten said of the study: "What we have here is a very clever attempt to skew the statistics by some very careful selection of the cases they chose to study. They chose to look only at divided panels. In doing that, they virtually ignored 86 percent of the cases on which Bork sat and on which a written opinion was issued. The truth of the matter is that Bork has been in the majority in 94 percent of the cases in which he has sat.

"By looking only at divided decisions, you really distort what is in fact a remarkable degree of harmony on the D.C. Circuit," Korten said.

Since 1982, he said, Bork has voted with moderate liberal Judge Ruth Bader Ginsburg 90 percent of the time, 83 percent with liberal Judge Abner Mikva, 80 percent with liberal Judge Harry T. Edwards and 79 percent with liberal Chief Judge Patricia M. Wald.