A stream of debate (including a previous special issue of this journal [25(1) 2014)] has made claims not just for "bringing knowledge back in" as the framing underpinning of the school curriculum, but that subjects associated with disciplinary and disciplined knowledge forms have a particular power and that these characteristics are important to preserve in curriculum frameworks. This paper draws on a major Australian research project studying school and university physics in the context of these arguments to revisit the issue of the "discipline" of physics and the curriculum logics for physics. Given that disciplines are social in origin and changing and expanding over time, can school curriculum be logically derived from the discipline to which they relate? Are questions about student engagement only questions about pedagogy and not curriculum? Does a focus on disciplinary knowledge mean that the role of school in forming identities and values is avoidable as a significant feature of what the curriculum does? The findings from the project are used both to illustrate and test these questions, and to challenge some over-simple assumptions about the verticality of this form of knowledge for education purposes.