The Fundamental Law of Education specifies that education shall aim at the full development of personality. This aim has been generally accepted by most of those engaged in educational theories and practices as well as in policy making. But interpretation of the aim has been so ambiguous that quite opposite views on education have been justified. Particularly problematic is that the original intent of the aim, i.e.education should aim at the full development of personality because it is broader and more basic than the formation of a good member of the nation, seems to be forgotten by most interpretations. This paper tries to clarify the weakness of the usual interpretation of the aim and to replace it with a more reasonable one. The concept of the personality in the original interpretation of the aim presupposes that human beings are unique in that they have the ability of reson. This characteristic enables them to pursue the universal values of truth, good and beauty, free from the causality of the material world. This interpretation has been accepted by most educational literature and policy documents. The concept of reason in the interpretation is almost the same as that in the age of the Enlightenment. Such a view has been persuasively critcized since the 19th century, particularly by so-called postmodern thinkers of the present. The above interpretation of the full development of the personality neglects these criticisms and, as a result, becomes an abstract concept which fails to have concrete effect on educational practices. A dificulty in educaionsl theories based on the Enlightenment concept of the reason is that a clear distinction is made between adults and children, namely, rational adults educate irrational children until they become rational. Viewed in this way, children's ability to reason has no place in education and neither equal relationaship nor mutual understanding between adults and children can be established. Then education becomes just another name for conditioning children by adults. This is a logical consequence of the Enlightenment theory of education that justifies the transformation of public education into national education. Although human beings may bear different values in different societies and among individuals in the same society as well, they may find common values if they make an adequate effort to do so when necessary. At least this possibility should not be denied even before they try. The ability to find a common value when necessary may be called reason, because it is what makes human beings understand each other in an equal relationship. Education that aims at the full development of personality based on this understanding of reason means to enhance mutual understanding of human beings. This effort is mainly made by adults upon children within a certain society, but in principle it is open to all human beings.
