<p> In the field of pedagogy, the contrast of "theory and practice" has been used for over 100 years; many studies have been based on the structure “from theory toward practice”, trying to apply theories produced by science to educational practices. However, as pointed out in Niklas Luhmann's argument, we cannot assume a simple relationship between the education system and the scientific system in which the former is based on the theory developed by the latter, because the two systems belong to different functional systems and have each accumulated their own history. In other words, the latter judges every activity in the light of a binary code of true/not-true, whereas the former judges everything on the basis of a code of better/inferior. Hence, for example, a theory that is highly evaluated in the latter is not equally highly evaluated in the former.</p><p> In addition, the scientific system, which was developed as a system of observation of other social systems, differentiates itself under the influence of existing concepts in other social systems. These differentiated sub-systems gradually subdivide and develop their own disciplines with the assistance of previously developed disciplines. At the same time, there are also disciplines that, as a result of relying on the existing concepts, seem to have, to a certain extent, correspondence with the differentiation of the social system; some similarity may be found in self-observation within these functional systems and disciplines within the scientific system. Each functional system and system of science, however, is based on a different binary code, and cannot be considered identical. For example, even when the scientific system of education is interested in 'how to educate better', it can only determine whether a finding such as that 'children are better educated by using certain methods' is true or not. An education system based on a different binary code would not necessarily accept the same finding.</p><p> Furthermore, within the internal subdivision of the education system, the scientific system (education science) which observes them will also tend to subdivide itself to diversify its programme. In this context, the relationship between the sub-systems of science and those of the education system also tends to diversify. What applies to one combination of systems does not necessarily apply to another.</p>