这又是一个出自圣经的短语。在《新约 马太福音》，耶稣责备法利赛人身为无知百姓的领导，却对真理视而不见，导人于迷。“Let them alone. They are blind leaders of the blind. And if the blind leads the blind, both will fall into a ditch.”Matthew 15:14 后来人们就用该短语表达以下的意思：The incompetent leading others who are also incompetent. 问道于盲，外行指导外行，半斤八两