Inherent in most school curricula is some sort of curriculum hierarchy--that is, an assumption that some school subjects are more valuable than others. This paper examines the epistemological assumptions that underpin one such curriculum hierarchy, which I refer to as "the traditional curriculum hierarchy". It is a pervasive and problematic idea which maintains that supposedly abstract school subjects, like mathematics and physics, are more valuable than subjects associated with concrete experience, practicality and the body, such as physical education and vocational subjects. Drawing on Dewey, an alternative, non-hierarchical theory of curriculum will be proposed. Contrary to common misinterpretations of his ideas, it is argued that Dewey did not prioritise student interests over disciplinary content. Dewey proposed a curriculum grounded in authentic social problems that required students to draw simultaneously on knowledge and methods from multiple disciplines in an interconnected manner in order to work through such problems. Current policies and initiatives, especially the Australian national curriculum and the English Baccalaureate, are discussed.