C. Clyde Ferguson, visiting professor at the Law School, said yesterday that he "turned down a number of specific positions in the area of foreign policy" offered by the Carter administration so that he could continue his writing and teaching here.

Ferguson, who wrote position papers on the South African situation for the Carter campaign, said he will continue to advise the Carter team on foreign policy and national security.

The former U.S. ambassador to Uganda said the new administration approached him "in terms of positions in the State Department, ambassadorships, and in the national security area."

The press duty officer at the White House last night confirmed that Ferguson may have been offered positions in the Carter administration, but said there was "some doubt" about the offer of am- bassadorships because the commission to recommend ambassadorial appointments was just now being established.

Ferguson said he believes he can have more general impact on foreign policy by staying at Harvard, finishing his two books and consulting with the government on a part-time basis.

This year and next he will finish his book on the diplomatic history of the Nigerian civil war, and the more major treatise on international human rights he has been working on for 20 years, Ferguson said yesterday.

Ferguson told one of his classes that he might miss some sessions in the spring to make some short diplomatic consultations which will probably include a stop in Geneva, one of his students at the Law School said yesterday.

Ferguson calls himself "one of the major fathers of the whole concept of affirmative action," citing a controversial paper he wrote in 1957 and a Civil Rights Commission paper in 1963 that he said led to the incorporation of Title Seven in the Civil Rights Act of 1964 that year.

In a diplomatic role, Ferguson said he was able to obtain international procedures to deal with human rights violations and actually drafted the United Nations Educational, Scientific and Cultural Organization's declaration on race relations