Three of the nation's leading scientists joined with two social scientists last night in urging the election of Lyndon Johnson at what may have been the lowest-keyed political rally of the campaign.

Moderator Lincoin P. Bloomfield, professor of Political Science at M.I.T., opened the meeting by reading a telegram from the President. But the audience applauded only politely and the panel discussion began.

The topic was "The Presidency in the Atomic Age," and the point each speaker made was the same: that Barry Goldwater is not fit for that office. But none of the panelists was trying to convince anyone of anything; they didn't need to.

Many in the audience wore the buttons of the sponsoring organization, Scientists and Engineers for Johnson and Humphrey. And most had apparently come simply to be told how right they are in thinking as they do.

The panelists emphasized the complexity of life in the nuclear age, and the necessity that our president possess "qualities of leadership and judgement." They spoke in paragraphs, and for the most part made their points by anecdote or implication, understating those conclusions they drew.

George B. Kistiakowsky, Abbot and James Lawrence Professor of Chemistry, for example, was "not convinced that a position of military weakness might not be more dangerous" than our present posture.

Occasionally one of the speakers was amusing. "As we listen to Sen. Goldwater," said Jerome B. Wiesner, Dean of the School of Science at M.I.T., and an adviser to Kennedy and Johnson, "we set the feeling he's running against the Presidency, that maybe he's trying to cut it down to his own size."

But only Stanley Hoffman, professor of Government, rose to a level of sustained epigram. "Even the Germans flinch," he said, "at Sen. Goldwater's mixture of the big stick, the large mouth and the small brain."

Deploring Goldwater's tendency to polarize situations, Hoffman maintained that the "kind of foreign policy he advocated would turn into a perpetual game of chicken."

Fear of Frustration

Wiesner echoed Hoffman's fear of a "foreign policy of frustration." He said the Arizonan has "said he thinks a nuclear war is inevitable in this century. If as President he found the pressure of avoiding such a conflict unbearable, he might just decide to get it over.

Both Kistiakowsky and Charles H. Townes, provost of M.I.T. stressed the importance of a level-headed attitude towards science and technology. "One seems to be able to do almost anything," said Townes, who invented the laser and the maser. "We must not let space and other scientific exploration be limited by lack of foresight."

Kistiakowsky, a special assistant for Science and Technology to President Eisenhower, emphasized the crucial role to advisers to a President. He declared himself horrified at the prospect of Goldwater's advisers.