Someone who is resigned to defeat without offering positive suggestions(noun)
Someone who refuses to do what is asked or does the opposite of what is asked(noun)
WordNet. Princeton University. 2010.
Use "negativist" in a sentence
"You know, another thought I'm having is that I frequently encounter a sort of "negativist peer pressure" that comes from people who are close to one another."
"But he replied to me "My dear Peter, nobody would want to be an illogical negativist.""
"Imbued with the righteous moral fervor of a revolutionary, the negativist — to introduce a new literary type — is more persuasive than the encomiast, who tends to resort to the bland, formulaic language of praise."