The Netherlands have a problem regarding quality as well as equality in their school system. Many students fail to reach minimal skill levels and underachieve with respect to their own learning capacities. They end up on educational levels that do not correspond to their learning potential, especially when their parents do not speak the language or cannot afford tutoring to exploit this potential. In this article, we argue that important reasons for this development lie in a lack of validity of judgments on various levels of the educational system. We summarize these reasons into 8 theses about the validity of methods, starting from methods of testing and assessment, over the design of the teaching process and underlying paradigms, and ending with the more general cybernetic effects of school policy and the meritocratic social paradigms in which they are embedded.