A little knowledge is a dangerous thing
A little knowledge is more dangerous than no knowledge at all. At least a person who does not know anything can claim of not knowing anything. He can be truthful to himself and the society. But a person with incomplete knowledge is neither here nor there. He cannot say that he knows nothing nor can he say that knows all. Therefore when the situation arises his knowledge is at test, he is unable to give the correct assessment. He thus opens himself to ridicule and cause harm. For example, a doctor who is not fully qualified will put the life of a patient in danger and instead of doing good will do more harm. The same is true for a car-driver, a technician a school teacher or any other person who is not well versed with his job. Only when a person has complete knowledge about his profession or subject he/she is capable of being useful to society.