The difference between an adult and a children, is that an adult has the freedom to make his own decisions, while the children has to accept the parent's decisions. This relationship is known as a paternalism. Paternalism is also present between adults in government regulations and social welfare, specially in medicine and health. The justifications of paternalism are ignorance, prevention, externalities, and resolution of disagreements. In the presence of paternalism, irrational and emotional disagreements between parties increase, and unexpected effects on the prevention of negative consequences appear. A cost and benefit analysis can be used to evaluate the effectiveness of paternalism.