Teachers in different countries, when judging the achievement of their students, do not use absolute standards but seem to work by comparison. The paper describes the reason for and the philosophy behind relative judgement in education. The explanation for the frequent use of relative testing in education is that it has a selective function in the classroom. The selective approach does fit in an educational philosophy regarding the place of schooling in our society. The philosophy does not possess a theoretical framework nor a clear description of its content. Six statements typical of the selective philosophy are discussed. They relate to the paucity of jobs on the market, to competition, the distribution of talent, and the supposed attributes of good school tests. The statements are related to each other in order to demonstrate how they can form a coherent system of opinions about how schooling ought to be organized. It is concluded that no philosopher can solve the problem of the educator who realizes that he is measuring instead of educating. Finally, it is argued that the problem of setting up a non-selective organization is a technological matter - a matter of choice for other learning strategies and other measurement techniques.