1
general::
Those lacking the skills or knowledge for something are being guided by equally inept individuals. For example, Bill's teaching his son carpentry; that's a case of the blind leading the blind. The expression is found in the New Testament as one of Jesus's teachings (Matthew 15:14; Luke 6:39). [c. 1600]
American Heritage Idioms
2
general::
Phrase(s): The blind leading the blind
Prov. Someone who is not capable of dealing with a situation is guiding someone else who is not capable of dealing with it. (See also a case of the blind leading the blind.) • Jill: Mike is helping me fill out my tax forms this year. Jane: Is he a tax expert? Jill: He read a book about income tax once. Jane: Sounds to me like the blind leading the blind. • Nathan offered to be my guide through Philadelphia, but since he’d never been there before either, it was a case of the blind leading the blind.
McGrawhill's American Idioms And Phrasal Verbs