Distinguishing between advocacy for a music education and justification for a music education is a theme running through a number of my blogs. 
Perhaps some will find the distinction merely semantic, typically academic, unhelpful and of no practical use. Perhaps some will think the first feeds the second. Perhaps you just haven’t given it a thought. Perhaps you will stop reading now.
I will argue, with as few words as possible, that the purposes of advocacy and the purposes of justification are different and helpfully so.
WHAT IS ADVOCACY FOR?
Advocacy is a necessary strategic tool in the art of political persuasion central to securing funding and above all recognition.
The art of political persuasion requires the skilful use of rhetoric involving the deployment of claims drawn from a variety of sources, some reliable, some less so. Close scrutiny of claims is not required or expected. 
WHAT IS JUSTIFICATION FOR?
Unlike advocacy justification is not concerned with securing funding or even a place in the curriculum, although it may help, but about clarifying and understanding purpose.
In clarifying purpose it becomes possible to justify music as a school subject. There is a basis for understanding music’s relationship to other subjects, to the whole. There is a basis for planning a curriculum and for devising pedagogical approaches that together will go towards satisfying the purposes of a music education.
This is important if music is to be a subject and more than a participatory activity in the same way that physical education is more than sport.
Music educational advocacy is a necessary part of being in a market place where resources must be fought over and where the struggle for recognition goes on.
On the other hand, justifying a music education is necessary in clarifying purpose and discerning the ethical demands placed upon those who teach.
While we need to work at both, and marginalized voices certainly need advocates, much greater attention needs to be given to working at and refining the justifications we make for music education. After all, as Chris Philpott reminds us, ‘music can be bad for you’. 
 See Blogs of 29.12.13; 13.4.14; 18.4.13; 31.10.14.
 Wayne Bowman (2005) defines advocacy as ‘…promising the world, without asking about the circumstances under which its promises might be realized, or acknowledging their contingency. It invests all its energies and resources rhetorically and politically, treating musical value as self-evident.’ See ‘Music education in Nihilistic Times’, in Music Education for the New Millenium: Theory and Practice for Music Teaching and Learning, edited by D. K. Lines. Oxford: Blackwell Publishing.
 See Philpott, C. (2012) The justification for music in the curriculum: music can be bad for you. In (eds) Chris Philpott and Gary Spruce pp. 48-63. Debates in Music Teaching, Routledge: London.