Sentence:  We may say that his attitude <WSD>was</WSD> foolish , since he may have been a success had he learned some human relations skills ; or we may say that his attitude was commendable , showing his independence of mind , in his refusal to adjust to the opinions of others . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)