BG Chap 18 - Knowledge in the mode of ignorance
That knowledge by which one is attached to one kind of work without reason, not concerned with truth, and which is meager, is in the mode of ignorance. This knowledge arises from one’s own speculation without reference to scriptures, and is absorbed in only one material action such as bathing, eating or associating with women, and is without attachment to Vedic actions such as sacrifice or charity. It does not have the goal of arriving at truth and is insignificant like the knowledge of an animal.
Knowledge concerning the spirit soul beyond this body is called knowledge in the mode of goodness, knowledge producing many theories and doctrines by dint of mundane logic and mental speculation is the product of the mode of passion, and knowledge concerned only with keeping the body comfortable is said to be in the mode of ignorance.