President Reagan last night was both criticized as a manipulator of public opinion and hailed as a peacemaker in a discussion sponsored by a local anti-nuclear group.

"It wasn't really a summit, it was the pits," said Professor of the History of Science Everett I. Mendelsohn, one of three speakers in a forum sponsored by the Eighth Congressional District Nuclear Freeze Committee.

"They both returned from Geneva with empty hands but big smiles," Mendelson, a peace activist and authority on arms control, told the audience of 60 assembled in Radcliffe Yard's Longfellow Hall.

"In the face of a nuclear arms race that is escalating into space and squandering our resources, they did not live up to their duties," Mendelsohn said in the discussion entitled, "After the Summit--Now What?"

Another speaker, the Rev. Nick Carter, also criticized the effectiveness of Reagan's performance in his November meeting with Soviet leader Mikhail Gorbachev.

The conference was "nothing more than pleasant chit chat," said Carter, a minister of a church in Beverly, Mass.

"I give them a failing grade. For all the celebration, the arms race continues," Carter said.

But Marshall I. Goldman, associate director of Harvard's Russian Research Center, said that Reagan in fact had moved the superpowers closer to peace.

"Reagan emerges as a man of peace and movement," Goldman said.

Even though there was no agreement to limit nuclear arms, he added, the two sides had moved closer to an understanding on which to base further dialogue.

An arms agreement "would have been unbelievable," Goldman said