In more than 300 years at Harvard University, Sen. John H. Chafee (R-R.I.) remarked to the Senate the other day, no professor has ever lost tenure, including one man who murdered his wife and went to the electric chair with his tenure intact.

Though it was later revealed that Chafee had overlooked two Harvard professors who lost tenure in the 18th Century, his point was clear - that it is almost impossible to remove professors once they have attained tenure.

The issue is part a controversy now raging in the academic world and Congress whether sich professors should be compelled to retire at 65 while other Americans could stay on the job until 70.

In the last several months, both houses of Congress passed by over whelming margins amendments to the Age Discrimination in Employment Act of 1967, which bars discrimination on the basis of age between 40 and 65. The amendments, which would raised the upper limit to 70, passed with remarkable suddenness, but not before the Senate found time to narrowly approve two exemptions for tenured colledge and university professors for upper-echelon business executives whose pensions, not including Social Security benefits, exceed $20,000 a year.

the House version didn't exempt anyone, and a conference committee was forced to iron out the differences. Aides on the relevant committees say there is little likelihood of compromise before January, and neither side appears to be yielding much. In the meantime, lobbying around the issue for exempting tenured professors has become intense, with university administrators, for the most part, on one side and faculty groups on the other.

"If it passes, it's a direct attack on the tenure system," said Morton Baritz, general secretary of the American Association of University Professors, an 80,000-member organization that opposes the exemption. "It's unprincipled and highly discriminatory to single out tenured professors. Administrators, clerical workers and nontenured professors can all go up to 70, he said.

But supports of the exemtion say that, with declining enrollments in higher education and with 60 per cent of all professors already tenured, raising the retirement age would make it impossible to attract new blood - which they say is vital to the university atmosphere - and would slow efforts to hire more women and members of monority groups. They say tenure bestows lifetime job security, a privilege not accorded most Americans.

"the reason for the exemption," Chafee said in a telephone interview, "is that with tenure their performance is not subject to objective evaluation . . .If you are 66 and you work for Merrill Lynch and you're not performing well, you can be canned. But if you are a 66-year-old Stanford professor and you're not producing you're locked in."

Sen Daniel Patrick Moynihan (D.N.Y.), who relinquished a tenured post at Harvard when he was elected to the Senate last year,said during the debate that failure to exempt professors would have "a devasting impact on the quality of American education."

Moynihan cited figures from a Harvard study that show that between 1980 and 1985, about 35,000 doctoral degrees will awarded each year, and that the 3,000 collegues and universities will hire about 3,700, or roughly one in nine. Without the age act exemption, he said, that figure would be cut by more than half , to 1,600, which would mean, on the average, that each institution could hire only one new faculty member every other year. And that, he said, "would be a formula for intellectual suffication."

Chafee pointed out that the average age of Nobel Prize-winners - not at the time they win their prizes, but when they do their prize-winning work - is 28. And the older professors whose presence retards the advance of the younger ones, he said, can keep working, but without tenure. He suggested that professors over 65 in lieu of tenure, could get annual appointments.

But Claude Pepper (D-Fla), who at 77 is chairman of the House Select Committee on Aging and principal author of the House bill, said it should be the responsibility of the universities "to weed out incompetence when incompetence is recognizes" rather than rely on a policy of forced retirement.

"Mandatory retirement will not solve the Ph.d. glut or the problems universities visit upon themselves through their refusla to evaluate the competence of tenured professors," Pepper said in a letter urging senators to oppose the affirmative action argument "insidious," because "it advocates age discrimination in the name of abolishing race and sex discrimination."

A Pepper aide, to counter Moynihan's figures, recited statistics from the State University of New York, which has no mandatory retirement age. Only 12 professors over 65 elected to continue teaching there out of a total faculty of 10,000, the aide said.

Professors, like other groups in the American economy, have been opting for early retirement in recent years. The battle, finally, comes down to change that trend. Each side has its own statistics ti bolster its position.

A new study by professors Everett Caril LaddJr., David D. Palmer and Seymour Martin Lipset, described in a recent issue of the Chronide of Higher Education, found that a "significant number" of tenured professors would change their retirement plans if the retirement age were raised.

The study, which was conducted before congressional debate on the current legislation, found that halo of all faculty members said they would retire by 65 and only 15 per cent contemplated teaching full'time beyond then.

But Ladd, Palmer and Lipset also found that the closer professors are to retirement, the more they "revise upward" their retirememt plans. They found that only 13 per cent of professors between 50 and 54 envision retiring at 67 or later, compared to 18 per cent between 55 and 59 and a whopping 30 per cent between 60 and 64. They found that the most accomplished scholars and teachers are those who most want late retirement.

If incentives were increased, however, many professors said they would consider retiring early. Sixty per cent of all professors between 53 and 62, the study said, would "respond positively" if they were assured of pension benefits equal to what they would be at the mandatory retirement age."