One of our graduate students at Brown, Jed Silverstein, is writing a dissertation concerned with issues in this vicinity, so I asked him if he'd like to answer this question. Here is what he had to say:
"In recent times, political philosophers such as Susan Okin, Eamonn Callan, and Rob Reich have shown persistent interest in the philosophical significance of children. However, their interest in children generally focuses on the legal and political relationship between the state and the family in a liberal democratic society, and less on the moral status of children within the home. Other philosophers such as Gareth Matthews (sadly, recently deceased) directly explore the moral status of children, and question the prevailing doctrines of developmental psychologists such as Piaget. The upshot of Matthew's view -- sometimes known as child liberationism -- is that society systematically denigrates children on the unwarranted grounds that they are morally and cognitively deficient.
"An important consideration to keep in mind when exploring philosophical questions regarding the moral and political status of children is that the conceptual tools of the philosopher are not appropriate to adjudicating disputes about empirical propositions. Whether children have poor impulse control or are particularly self-involved is most profitably examined within the confines of social science. Nevertheless, the philosopher has a critical role to play in making clear the logical relations between empirical propositions and the moral and legal rights of children -- in essence, the philosopher lays the conceptual framework that can guide social scientific research and explain the significance of its findings."