Sentence:  To guard against the tyranny of a numerical majority , Calhoun developed his theory of `` concurrent majority '' , which , he said , `` by giving to each portion of the community which may be unequally affected by the action of government , a negative on the others , <WSD>prevents</WSD> all partial or local legislation '' . 
Meaning of the word marked with <WSD> tags:  keep from happening or arising; make impossible