Attachment theory is said by psychologists to be at the basis of all good development. It is not merely a child's emotional ability to attach to one person and to maintain a relationship; it goes throughout their entire lives. It forms the basis of their educational achievement and of their intellectual ability, as well. If you want on pure economics to come up with a policy that will add to our society's wellbeing, privilege those days. Privilege the ability of parents to stay home with children, if that is what they choose to do. 