President Ford dismissed Secretary of Defense James A. Schlesinger'50 because his actions were undermining the foreign policy of Secretary of State Henry A. Kissinger '50, four Harvard Government professors said yesterday.

"Kissinger has driven out Schlesinger," Peter M. Lange, assistant professor of Government, said yesterday, adding that the "marked difference of opinion" between the two officials on detente with the Soviet Union was the main cause of Schlesinger's dismissal.

Karl W. Deutsch, Stanfield Professor of International Peace, yesterday agreed with Lange. "If both men had remained in office, a coherent foreign policy would have been impossible. In the last few months, Schlesinger's office has released a stream of information designed to stop any major agreement at the SALT (Strategic Arms Limitation) talks."

"President Ford had the choice of dropping any effective effort at arms control or dropping Mr. Schlesinger--so he dropped Mr. Schlesinger," Deutsch said.

The professors disagreed about whether or not Vice President Nelson A. Rockefeller's announcement that he would not seek the vice-presidency in 1976 was related to the dismissals.

Michael E. Mandelbaum, assistant professor of Government, said yesterday he believes the two incidents were unrelated. "Rockefeller got tired of being the target of right wing abuse and decided to spare himself the humiliation of being left to twist in the wind by Ford."

Samuel P. Huntington, Thomson professor of Government, said yesterday he disagreed with Mandelbaum's position. Voluntarily removing himself from consideration "goes against Rockefeller's previous actions in his 30 years in politics," Huntington said.

Huntington also said Rockefeller's announcement might be designed to quell conservative Republican criticism about the dismissal of Schlesinger and to prevent Schlesinger from the becoming the right's "martyr" to the cause of military preparedness.