spe·cious 
/ˈspi:ʃəs/ adjective
/ˈspi:ʃəs/ adjective [more specious; most specious] formal : falsely appearing to be fair, just, or right : appearing to be true but actually false
▪ a specious argument ▪ He justified his actions with specious reasoning.
▪ a specious argument ▪ He justified his actions with specious reasoning.
— spe·cious·ly adverb, formal
— spe·cious·ness noun [noncount] formal
▪ the speciousness of his reasoning
▪ the speciousness of his reasoning
