The catalyst for this paper is the ongoing debate concerning formal and informal approaches to pedagogy within the music education literature. I utilise a chapter by Philpott (2010) as a means to continue discussion about the apparent dialectic between formal and informal approaches to music learning and the case Philpott raises for radical change in "three moments" of music education history. In engaging with the concerns in Philpott's chapter I also seek to bring to a wider audience the ideas developed by a group of sociologists of education who draw on the work of Basil Bernstein (2000) and critical realism (Moore, 2013) to argue for a realist theory of knowledge. I utilise these "social realist" ideas as a means to engage with the theme of access to what Michael F.D. Young has recently termed "powerful knowledge" (Young, 2012). As Bernstein (2000) suggests we must have an understanding of the recontextualising principles that come into play whenever the classification of knowledge undergoes change, as ideologies shift and change. I argue for a balance between powerful forms of pedagogy "and" powerful forms of knowledge based on an awareness of the essentially differentiated nature of knowledge.