Common sense is not the kind of education you receive through formal training.You don’t go to school to acquire common sense. It refers to having sound judgment, not necessarily based on specialized knowledge.
When you are smart, level-headed and able to understand and assess a situation.You acquire it through living.
But common sense may not be as common as we think. It varies from person to person, because none of us has identical knowledge and experiences.It is always difficult to deal with people who lack common sense or basic sense.