He then studied at the University of Cambridge on a Fulbright Fellowship ( 1956 -- 1957 ) .
He then completed his doctoral work at Harvard , earning his Ph. D. in government in 1961 .
He then studied at the University of Cambridge on a Fulbright Fellowship ( 1956 -- 1957 ) and completed his doctoral work at Harvard , earning his Ph. D. in government in 1961 .