(figurative) a course of action that is unproductive and offers no hope of improvement; "all the clues led the police into blind alleys"; "so far every road that we've been down has turned out to be a blind alley"
lacking in insight or discernment; "too obtuse to grasp the implications of his behavior"; "a purblind oligarchy that flatly refused to see that history was condemning it to the dustbin"- Jasper Griffin
conduct an inquiry or investigation of; "The district attorney's office investigated reports of possible irregularities"; "inquire into the disappearance of the rich old lady"
investigate scientifically; "Let's investigate the syntax of Chinese"