He was president of the International Political Science Association from 1970 to 1973 , president of the International Social Science Council ( ISSC ) , which was founded by UNESCO , from 1973 to 1977 , vice-president of the International Sociological Association from 1966 to 1970 , and chairman ( from 1970 to 1976 ) and co-founder of the European Consortium for Political Research ( ECPR ) .