"If professors aren't going to give one, you're not going to be afraid of getting one," said Cassandra Thomas, a junior from New York City. Like many students on this perpetually balmy and aromatic campus, where the quiet is punctuated by the sounds of splashing fountains, birds and bicycle brakes, she was more concerned about new requirements that students stop shopping around for courses well into each academic quarter to avoid getting failing marks. "It cuts down on the whole experimentation process," she said. Easy to Try Again

As things now stand, Stanford's students, many competing for scarce slots in prestigious law or medical schools, can withdraw from classes on the eve of final examinations with no notation on their transcripts. After the students withdraw, they are free to take the courses again and again, until they get grades they like. This practice generates blemish-free transcripts.

But beginning in the 1995-96 academic year, students who drop classes between the fifth and eighth weeks of a quarter will have a W placed on their transcripts to mark the withdrawal. Students who are still in courses after that point will be in them for keeps, with the prospect of a failing grade if they do poorly. The changes will also bar students from retaking a course more than once, and all repeated courses will be recorded as such on transcripts.

Professor Mahood, who said she had been "on the other side of the barricades" when the liberalized policies had been adopted, said they represented too much of a good thing. "There were legitimate reasons for wanting to make the grading system more flexible and to encourage students to be more adventurous in their course selections. Stanford liberalized things like everyone else, but just went further. Probably it overstepped. Now it's trying to bring its policies back into balance."

She predicted that the changes would help correct the distribution of grades at Stanford. "There's a good reason we give A's and B's," she said. "It's not because we're squishy, but because most of those who see they're going to get a C drop the course." But she said the impact of the changes would be far smaller than necessary, and she predicted that another faculty committee would soon address the issue.

"If you think of grades as the slang we use to communicate with students and the outside world, we have a problem in that our vocabulary has really shrunk," she said. "We can't communicate with as much precision as would have been possible in the mid-1960's." Some Object to Changes

Ronald Rebholz, an English professor who was one of three dissenters at Thursday night's meeting, asserted that the faculty group had fallen into a "punitive mode" and was "branding students."