Yeah I have to agree Matt. Minarchy is as relative a term as socialism and doesn't inherently identify if it is voluntary. Anarchy implies voluntaryism because it defines a society without rulers, therefore no coercive rulers.

Minarchist have their own war to fight amongst themselves to define themselves by more specific and more ethical terms not laid out in the current definition. That being said, I don't consider myself a minarchist in the same way that I don't consider myself a conservative, because both imply relative terms surrounding the existence of a possible / probable state.