The Massachusetts' Teachers' Loyalty Oath came under attack Wednesday, when a Salem representative introduced a motion before the Joint Committee of Education requesting its repeal.

The oath, which is being challenged in the state courts by two M.I.T. professors, must be signed by all public and private school teachers in Masachusetts, including university professors.

Rep. Michael J. Harrington (D-Salem) also urged the repeal of a similar oath which is required of public employees. He was joined in his appeal by members of the Massachusetts Federation of Teachers and of the American Jewish Conference.

Each teacher who takes the loyalty oath must affirm support of the constitution of the United States and of Massachusetts. He must also promise to "faithfully discharge the duties of the position," a clause which the professors believe to be dangerously vague.

Joseph Pediosky, assistant professor of Mathematics at M.I.T., and William Watson, associate professor of History there, refused to sign the oath last fall, calling it an "unjustified deterrent to free speech and belief." They have also questioned the "faith in orthodox nationalism" which they say the oath requires.

There is little chance that the Joint Committee will vote favorably on Harrington's motion, according to Gerald A. Berlin, the Boston attorney who has been handling the case.

Berlin expects the Superior Court to pass the case on to the Supreme Judicial Court, where it will be argued in late April. Because the oath is no innocuous, Berlin believes that its repeal may set a precedent for the repeal of many state teachers' oaths which are more severe.