Sentence:  Thus , if what is at issue <WSD>is</WSD> whether `` All S is P '' , it is indifferent whether `` Some S is not P '' or `` No S is P '' , since in either case the judgment in question is false . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)